Design of Waterborne Isocyanate -free Poly (Hydroxy Urethane)s- Poly (Butyl Methacrilate) Hybrids via Miniemulsion and Properties of the Cast Films.

THÈSE PRÉSENTÉE POUR OBTENIR LE GRADE DE DOCTEUR DE L’UNIVERSITÉ DE BORDEAUX ÉCOLE DOCTORALE DES SCIENCES CHIMIQUES Spécialité : Polymères ET DOCTEUR DE L’UNIVERSITÉ DU PAYS BASQUE ÉCOLE DE MASTER ET DOCTORAT Spécialité : Chimie appliquée et polymères Par Boris BIZET Design of Waterborne Isocyanate-free Poly(Hydroxy Urethane)s – Poly(Butyl Methacrylate) Hybrids via Miniemulsion and Properties of the Cast Films Conception d’hybrides PolyHydroxy Uréthanes sans Isocyanate – Poly(Méthacrylate de Butyle) en mini-émulsion et propriétés des films résultants Sous la co-direction de : Pr Henri CRAMAIL (Université de Bordeaux) Pr José Maria ASUA (Université du Pays Basque) Co-encadrant : Dr Etienne GRAU (Université de Bordeaux) Soutenance prévue le : 27 Février 2020 Membres du jury : Dr. Elodie Bourgeat-Lami Directeur de Recherche, Université Claude Bernard Lyon Rapporteur Dr. Christophe Detrembleur Chercheur confirmé, Université de Liège Rapporteur Dr. Lise Maisonneuve Docteur, Michelin Examinateur Pr. Maria Paulis Professeur, Université du Pays Basque Examinateur Pr. Sébastien Lecommandoux Professeur, Université de Bordeaux Examinateur (cc)2020 BORIS ERIC ALAIN BIZET (cc by-nc-nd 4.0) GENERAL TABLE OF CONTENT Chapter 1: State of the Art & Objectives …………………………………….. 5 Part A: Hybrid – Non Isocyanate Polyurethanes (H-NIPUs).. 7 1. Introduction ………………………………………………………………………………………………………….. 9 2. NIPUs in a nutshell ………………………………………………………………………………………………. 10 2.1. NIPUs – what are they? ………………………………………………………………………………………. 10 2.1.1. Different pathways to make NIPUs …………………………………………………………… 10 2.1.2. Transurethanization and Aminolysis of cyclic-carbonates compounds ............ 11 2.2. Challenges to overcome ……………………………………………………………………………………… 12 2.2.1. Transurethanization process ……………………………………………………………………. 12 2.2.2. Aminolysis of cyclic-carbonates – Towards PHUs ……………………………………… 14 2.3. Valorization of NIPUs …………………………………………………………………………………………. 18 3. Hybrid-NIPUs: novel materials for a broad range of properties ………………………........... 18 3.1. NIPU-Epoxy ……………………………………………………………………………………………………….. 19 3.1.1. Epoxy-NIPUs through the reaction of partially carbonated epoxy compounds 20 3.1.2. Epoxy-NIPUs through the reaction of homotelechelic prepolymers with curing agents ……………………………………………………………………………………………………………………………… 21 3.1.3. Epoxy-NIPUs through the incorporation of hydroxyurethane modifiers …….. 25 3.1.4. Epoxy-NIPUs from bio-based resources ……………………………………………………. 26 3.2. NIPU-Acrylics …………………………………………………………………………………………………….. 27 3.2.1. Unsaturated cyclic carbonates and their acrylic polymerization ………………… 29 3.2.2. (Hydroxy)urethane methacrylates – (H)UMAs ………………………………………….. 32 3.2.3. Unsaturated NIPU-prepolymers: Poly(hydroxy)urethane methacrylates – P(H)UMAs ……………………………………………………………………………………………………………………….. 37 3.2.4. Radical reactive (H)UMAs – Summary of the synthetic strategies ………………. 42 3.3. Other Hybrid-NIPUs …………………………………………………………………………………………… 46 3.3.1. Si-containing H-NIPUs ……………………………………………………………………………… 46 3.3.2. Biopolymer-containing NIPUs ………………………………………………………………….. 54 4. Concluding remarks …………………………………………………………………………………………….. 58 5. References …………………………………………………………………………………………………………... 59 6. Shortened forms ………………………………………………………………………………………………….. 70 2 Part B: Hybrid – Non Isocyanate Polyurethanes (H-NIPUs) 73 1. Introduction ………………………………………………………………………………………………………… 75 2. Water-soluble NIPUs …………………………………………………………………………………………… 76 2.1. NIPU synthesis using water as reaction medium ………………………………………………….. 76 2.2. Modification of NIPUs synthesized on organic solvents ………………………………………... 78 3. Hydrogels ……………………………………………………………………………………………………………. 81 4. Water-borne Dispersions ……………………………………………………………………………………... 82 4.1. Acetone-like process …………………………………………………………………………………………... 82 4.1.1. NIPUs dispersion by acetone-like transesterification processes ………………… 83 4.1.2. NIPUs dispersion by acetone-like aminolysis processes …………………………….. 87 4.2. NIPU dispersions through interfacial polymerization ………………………………………....... 89 4.3. NIPU dispersions by mini-emulsion polymerization …………………………………………….. 89 4.4. PHU dispersions by nano-precipitation ……………………………………………………………... . 90 5. Water-borne Hybrid-NIPUs (H-NIPUs) ………………………………………………………………..... 91 5.1. NIPU-Acrylics – HUMAs ………………………………………………………………………...................... 91 5.2. NIPU-Epoxy ……………………………………………………………………………………………………….. 92 6. Conclusions …………………………………………………………………………………………………………. 94 7. References …………………………………………………………………………………………………………... 95 8. Shortened forms ………………………………………………………………………………………………... 100 Part C: Objectives & Outline ....................................................... 101 Chapter 2: Bulk Synthesis of Bio-Based Poly(Hydroxy Urethane)s – PHUs…………………………………………………………………………………..... 105 1. Introduction …………………………………………………………………………………………………….... 107 2. Experimental ……………………………………………………………………………………………….…….. 109 2.1. Materials and methods ……………………………………………………………………………….…….. 109 2.2. Standard Procedure for polymerization …………………………………………………….………. 111 2.3. Bis-cyclic carbonate synthesis ………………………………………………………………….……….. 111 3. Results and Discussion ………………………………………………………………………………………. 112 3.1. Activated bio-sourced bis-cyclic carbonates (bisCCs) …………………………………………. 112 3.2. Copolymerization of bisCC-C4 and bisCC-C10 with mixtures of diamines ……………. 115 3.3. Thermal characterization …………………………………………………………………………………. 120 3.4. Viscoelastic behavior …………………………………………………………………………………….….. 121 3.5. Theoretical study of the polymerization behaviors of bisCC-C4 and bisCC-C10 ….….. 122 4. Conclusion ………………………………………………………………………………………………………… 124 5. References ………………………………………………………………………………………………………… 125 3 6. Shortened forms ……………………………………………………………………………………………...… 129 7. Supporting Information ……………………………………………………………………………………… 130 7.1. NMR analyses ………………………………………………………………………………………………...… 130 7.2. IR analyses ……………………………………………………………………………………………….……… 140 7.3. DSC analyses (Temperature ramp: 10°C.min-1) …………………………………………….……. 141 7.4. TGA analyses …………………………………………………………………………………………….……… 143 7.5. SEC traces …………………………………………………………………………………………….……..…… 145 7.6. DFT Study – Structures of the intermediates ………………………………………….……....……145 Chapter 3: Miniemulsion of Non-Isocyanate Polyurethane-Acrylics Hybrids and Properties of the Cast Films Thereof …………...…….. 147 1. Introduction …………………………………………………………………………………………….……...… 149 2. Experimental …………………………………………………………………………………………….……..... 150 2.1. Materials …………………………………………………………………………………………….……........… 150 2.2. Experimental design …………………………………………………………………………….…….......... 150 2.3. Miniemulsification and miniemulsion polymerization …………………………….……......... 151 2.4. Film casting …………………………………………………………………………………………….……...... 152 2.5. Characterization ……………………………………………………………………………………….…….... 153 3. Results and Discussion ……………………………………………………………………………….…….... 155 4. Conclusions …………………………………………………………………………………………….……........ 165 5. References …………………………………………………………………………………………….…….......... 166 6. Shortened forms …………………………………………………………………………………….……......... 169 7. Supporting Information …………………………………………………………………………….……...... 170 7.1. Side Reactions …………………………………………………………………………………………….……. 170 7.2. Solubility …………………………………………………………………………………………….……........... 175 7.3. Miniemulsion polymerization using thermal initiators ………………………….……........... 179 7.3.1. Formulations with thermal initiators …………………………………………….……...... 179 7.3.2. Results and discussion …………………………………………………………………………… 182 7.4. Formulations with redox initiators …………………………………………………………………… 184 7.5. SEC-MALLS Traces …………………………………………………………………………………………… 187 7.6. DSC Traces ………………………………………………………………………………………………………. 188 7.7. Minimum Film Forming Temperature (MMFT) …………………………………………………. 189 4 Chapter 4: Bulk Synthesis of Bio-Based Poly(HydrocyUrethane)s – PHUs……………………………………………………………………………………… 9 1. Introduction ……………………………………………………………………………………………….… 193 2. Experimental ………………………………………………………………………………………………... 194 2.1. Materials and methods …………………………………………………………………………………. 194 2.2. Synthesis of waterborne grafted PHU-(meth)acrylic hybrids ……………………………. 194 2.3. Characterization ………………………………………………………………………………………..… 199 2.4. Film casting ……………………………………………………………………………………………….... 201 3. Results and discussion ………………………………………………………………………………….... 201 3.1. Synthesis of the functionalized PHUs ……………………………………………………………... 201 3.1.1. Methacrylate-terminated PHUs …………………………………………………………… 201 3.1.2. Methacrylate groups distributed along the PHU chains (multifunctionalized) 206 3.2. Synthesis of the hybrid latexes ………………………………………………………………….…… 209 3.3. Film properties ……………………………………………………………………………………………. 213 4. Conclusions …………………………………………………………………………………………………... 218 5. References …………………………………………………………………………………………………..... 220 6. Shortened forms ……………………………………………………………………………………………. 223 7. Supporting Information …………………………………………………………………………….…… 224 7.1. monoCC-GMA – Carbonated Glycidyl Methacrylate ……………………………………….…. 224 7.2. Telechelically-functionalized PHUs ……………………………………………………………...… 224 7.2.1. Formulations ………………………………………………………………………………..…… 224 7.2.2. NMR Spectra ………………………………………………………………………………...…… 228 7.3. Multi-functionalized PHUs …………………………………………………………………….....…… 232 7.4. Formulations used for the miniemulsions ……………………………………………….....…… 233 Chapter : General Conclusions …………………………………………….. 235 Conclusions Générales ..………………………………………..  Resumen y Conclusiones ..………………………………….... 247 CHAPTER 1 STATE OF THE ART & OBJECTIVES PART A HYBRID – NON ISOCYANATE POLYURETHANES (H-NIPUS) A PATHWAY TOWARDS A BROAD RANGE OF NOVEL MATERIALS Keywords: Non Isocyanate Polyurethanes - NIPUs Poly(Hydroxy)urethanes - PHUs Polymer-Polymer Hybrids NIPU-Epoxy NIPU-Acrylics NIPU-Siloxane Chapter 1 – Part A 14 often required. This usually yields time and energy consuming processes that is the bottleneck for upscaling. Scheme 2: Backbiting followed by urea formation in the transurethanization reaction of bishydroxyalkylcarbamates – adapted from Maisonneuve et al.14 2.2.2. Aminolysis of cyclic-carbonates – Towards PHUs 2.2.2.1. Monomer synthesis In a similar way to transurethanization, the formation of PHUs relies on the availability of very specific monomers, namely cyclic carbonate compounds. So far, research activities have been mostly focused on the synthesis of bis-cyclic carbonates followed by their subsequent aminolysis with amines. In 2019, Carré et al. published a review describing all the different routes towards the synthesis of (generally bio-based) 5-membered bis-cyclic carbonates and those are described in Figure 2.20 The main goal of this research field consists in getting rid of the use of phosgene, which is historically used in the reaction with a diol moiety to yield the corresponding cyclic carbonate. The description of the different routes towards the formation of bis-cyclic carbonates is out of the scope of this study as it has already been widely documented in the scientific literature.19,20 The focus will hence be made onto the two more widely utilized pathways, namely the carbonation of bis-epoxide compounds and the esterification reaction of diacids (or derivatives) with glycerol carbonate. The carbonation of bis-epoxide compounds with CO2 (regularly used as a sustainable C1 source for the synthesis of bio-based monomers) is carried out under high pressure and temperature. The activation of the epoxy moiety has to be performed with the help of a halide catalyst.24 Bromine-containing compounds usually are the catalysts of choice. This pathway can be utilized to carbonate various types of epoxides, ranging from mono-epoxide (such as glycidyl methacrylates) to more complex structures such as epoxidized vegetable oils,25 fatty-acid based26 or terpene-based monomers.27 Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 15 The esterification reaction of diacids with glycerol carbonate is another interesting route towards the formation of bis-cyclic carbonates. This pathway makes use of a derivative of glycerol, which is a by-product of the biodiesel production industry that has still not got any valorization path.28 It yields specific ester-activated monomers that have been showed to exhibit superior reactivity as opposed to aliphatic cyclic carbonates. As every esterification reaction, the acid moieties have to be chemically activated and the equilibrium has to be shifted towards the formation of the di-ester. This is usually performed though the chlorination reaction of the acid moieties, yielding di-acyl-chloride moieties,29,30 or the use of coupling agents. The combination of N,N′-Dicyclohexylcarbodiimide (DCC) with the catalyst 4Dimethylaminopyridine (DMAP) (also known as the Steglich esterification reaction) is often reported as it allows to reach very high conversions using very mild conditions thanks to the precipitation of the 1,3-Dicyclohexyl urea (DCU) urea by-product formed by DCC upon its reaction with the acid function.31 However, in both cases, the greenness of the process is reduced due to the formation of very high amounts of by-products. 2.2.2.2. Major challenges yet to overcome Apart from the difficult access to monomers, the aminolysis reaction of cyclic-carbonate compounds still is a complex reaction, the limits of which are still under investigation. In this review, we will only mention the major challenges that are summarized in Figure 3.  Enhancing the bis-cyclic carbonate reactivity Attemps to enhance of the aminolysis reaction by improving the reactivity of the cycliccarbonate moiety have been reported. This was done by either increasing the ring size or introducing specific moieties in alphaor beta-position of the cyclic carbonate moiety.14,15,20 The increase of the ring size is a synthetic challenge in itself, especially if phosgene-free pathways are desired. The most common moiety is the 5-membered cyclic carbonate, which is thermodynamically very stable. The scientific literature relates the synthesis of 6-, 7and 8membered rings, the thermodynamic stability of which is decreased, hence fostering their reactivity in particular towards amines.14,32–34 In order to increase the reactivity of 5-membered cyclic carbonates, specific chemical functions have been introduced in alphaor beta-position of the carbonate ring. In most of the cases, ether or ester moieties are incorporated in beta position of the ring.29 Acting as an electron withdrawing group, they increase the partial positive charge on the carbonyl carbon Chapter 1 – Part A 16 and making it prone to react with amines. Numerous other activations have been exemplified as depicted in Figure 3.20,35–38  Playing on the amine structure The structure of the amine governs its reactivity, the more nucleophilic the higher the reactivity. It is a general agreement that the reactivity of the amines follows the order tertiary amine < secondary amine < primary amine.39 The tertiary amines exhibit no reactivity in the ring opening of cyclic carbonates. In the case of primary amines, the reactivity is governed by the amine chemical structure and molecular weight.14,40–42 Aromatic amines are not reactive, and very substituted aliphatic amines exhibit poor reactivity. In addition to this, amines with strong electronwithdrawing groups in alpha or beta position with respect to the amino group were found to be more reactive. Moreover, lower molar masses of the amines increased the chemical reactivity for the aminolysis of cyclic carbonates.14,43  Polymerization conditions The formation of PHUs yields polymers of very high viscosity, which is the result of a very high density of hydrogen bonds.44 To overcome this limitation, several solutions can be employed. The most obvious one consists in increasing the reaction temperature, but this increases the probability of side-reactions to occur. The urea formation, due to the reaction of amine with the pre-formed urethane moiety is known to occur at a temperature higher than 100 to 120 °C.20 In the case of esteractivated bis-cyclic carbonates, the amidification reaction is also observed. Another way of breaking the density of hydrogen bond consists in using a protic solvent that provides a high degree of freedom in the motion of the polymer chain for it to continue reacting. This solvent should preferably be of high polarity to solubilize the monomers and to form a homogeneous reaction medium. Catalysis is also important. The precise description of each catalytic systems is out of the scope of this review, but it can be noticed that significant improvements of the kinetics of ring opening were achieved, notably when triazabicyclodecene (TBD) was used as catalyst. However, progressive conversion of the formed PHU into polyurea was also noticed, suggesting that careful attention has to be paid when selecting a catalytic system.45 Detailed information can be found in a recently published review from Sardon and coworkers.46  Molecular weights prospects with regard to PHU synthesis Despite extensive research activities, and even if PHU can seem promising candidates for the implementation of phosgeneand isocyanate-free pathways towards PUs, it is noteworthy to mention that low molar masses are usually obtained, which limits the mechanical properties. It has also to be pointed out that the solubility limits and the use polystyrene based calibration make unreliable the SEC measurements of the molecular weights complicating the comparison between results reported by different groups. Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 17 Figure 3: Strategies towards an improved aminolysis of cyclic carbonates – adapted from Maisonneuve et al.19 Cornille et al.15 and Carré et al.20 Reprinted with permission from Chem. Rev. 2015, 115, 22, 12407-12439. Copyright 2020 American Chemical Society. Chapter 1 – Part A 18 2.3. Valorization of NIPUs In short, in spite of being very attractive pathways, both transurethanization and PHU formation are still suffering from limitations cornering them at the academic interest. Very recent research have been focused on the potential use of PHUs as materials, notably by designing very specific – and often bio-based – monomers capable of polymerizing in bulk.6,10,53–61,30,31,47–52 This allowed for the growing knowledge of the structure-properties relationship of NIPUs that have been summarized in a review from 2016.62 In this context, there is a growing interest in the valorization of NIPUs via the design of polymer-polymer hybrids (also called H-NIPUs) that will be described in the next section of this review – Figure 4. Figure 4: Potential valorization pathways for NIPUs towards their industrial implementation (adapted from Caillol and coworkers15) 3. Hybrid-NIPUs: novel materials for a broad range of properties Hybrid-polymers are two or multiphase composites in which each phase is formed by a different material and at least one of them is a polymer. Polymer-polymer hybrids are formed by different polymers. The resulting properties of the final composites usually are a synergistic combination of those of the constituting materials. Polymer-polymer hybrids can be formed by simply mixing two polymers together, but more complex structures can also be achieved by grafting. This usually helps prevent phase separation that can occur especially when the two polymers have a poor compatibility. Quite a few examples of hybrid NIPUs (H-NIPUs) have been published and are summarized in this review as well as the underlying challenges that are rising from such technologies. Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 19 3.1. NIPU-Epoxy The synthesis of NIPU-epoxy hybrids is the eldest process for the formation of H-NIPU.63 In that work NIPUs were used as modifiers in order to improve the flexibility of epoxy resins for lacquers and adhesive applications. This pioneering work inspired numerous researches, that were well described by Figovsky.64 In 2017, Cornille et al.15 suggested a classification of three different chemical pathways towards the formation of a NIPU-Epoxy hybrids - Scheme 3. The first route consists in reacting partially carbonated epoxy compounds with a polyamine. Polyamines are able to react with both the epoxy and carbonate moieties to yield H-NIPUs. The second alternative is a 2-step process in which a NIPUprepolymer is formed prior to reacting in a second step to form the final H-NIPU. Finally, the formation of so-called Hydroxy Urethane Modifiers (HUM) has recently been reported as another possibility. It consists in forming a mono-hydroxy urethane that upon reaction with a polyepoxy yields the final H-NIPU. In all cases, it can be considered that the polymer-polymer hybrids form interpenetrating networks (IPN) in which the NIPU is tangled up with crosslinked epoxy resin.15,65 Scheme 3: Different routes towards the formation of polymer-polymer NIPU-Epoxy hybrids – adapted from Cornille et al.15 Chapter 1 – Part A 20 3.1.1. Epoxy-NIPUs through the reaction of partially carbonated epoxy compounds The partial carbonation of epoxidized compounds was the first approach to synthesize epoxyNIPU hybrids, likely due to the ease of access to the raw materials at stake in this synthetic process. Rokicki et al. pioneered this type on synthetic process by partially carbonating a bisphenol-A diglycidyl ether (BADGE)-based epoxy resin by fixation of CO2.63 Different degrees of modifications were achieved before further curing with triethylenetetramine (TETA) to form a 3D network - Scheme 4. Scheme 4: BADGE-based H-NIPU through the amine curing of a partially carbonated epoxy resin The authors noticed an increase in viscosity with an increasing degree of carbonation of the modified epoxy resin, that was explained by the presence of a high density of H-bonds within the polymer. Later the effect of carbonation on the viscosity was found to be epoxy-resin dependent.66 The reactivity of the partially carbonated macro-monomer with TETA was then measured by determining the gelation time. It was found that the gelation time decreased by increasing the carbonate content, hence suggesting that the energetic barrier for the reaction was higher for the epoxy than for the cyclic carbonate moieties. Interestingly, the introduction of carbonate moieties also allowed to decrease both the intensity of the reaction exotherm as well as the time needed to reach it, making such a process very interesting for safety purposes should high amounts of material be produced. Those findings were also confirmed by the work of Bürgel who ran a mechanistic study of this polymerization process.40 Trying to go beyond the use of partially carbonated BADGE-resin, they performed another study by synthesizing linear telechelic oligomers.67 It was found that both the degree of carbonation together with the functionality of the curing amine were playing a role in the preference of the amine to react either with the cyclic carbonate or with the epoxy moiety. More precisely, primary amines would rather react with carbonate moieties whereas secondary amines would react with both carbonate and epoxy moieties.40,65,67 A lower degree of covalent crosslinking in the final IPN was then obtained. The reaction temperature was also found to play a crucial role in the chemical process. Indeed, increasing the reaction temperature led to higher conversions,67,68 Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 21 shorter gelation times,63,66,68 lower viscosity,63,68 better homogenization of the mixture, and promoted reaction with the epoxy moiety to a higher extent.63,68 However, side reactions were also noticed starting at 100 °C, suggesting that there is room for optimization of the reaction temperature, which can be very system-dependent.40 When considering thermo-mechanical properties of the formed H-NIPUs, superior properties were obtained for the modified epoxy resins, especially in terms of impact resistance, hardness, and compressive strength.66 Good tensile properties could also be obtained , that were attributed to a physical crosslinking that occurs in the obtained IPN which can still be explained by the presence of unreacted cyclic carbonate moieties forming H-bonds with the –NH-functions of the hydroxyurethanes moieties formed upon polymerization - Scheme 5. As an outcome, synergetic effects were also obtained when hydroxyurethane-containing polyamines were synthesized and incorporated into NIPU-Epoxy hybrids.68–71 Scheme 5: Physical crosslinking by H-bonding in Epoxy-NIPU hybrids Figovsky et al. (Polymate Ltd) patented a process in which partially epoxidized compounds were cured with an epoxy resin and oligomeric amines for the preparation of H-NIPUs to be used for preparing constructive glues, sealants, coatings, construction materials among others.72 3.1.2. Epoxy-NIPUs through the reaction of homotelechelic prepolymers with curing agents This chemical pathway relies on a 2-step process in which an amino-telechelic NIPU prepolymer is first formed by reaction between a bis-cyclic carbonate and an excess of diamine monomer. The amino-telechelic NIPU (and more specifically in this case a PHU) prepolymer is subsequently cured Chapter 1 – Part A 22 with an epoxy compound – Scheme 6.61,73,74 This technology is particularly appealing for the design of materials with defined sequences of soft and hard segments within the final 3D-hybrid network. Scheme 6: NIPU-Epoxy H-NIPU formation through the preparation of poly(propylene oxide) bis-cyclic carbonate amino homotelechelic prepolymer prior to further curing with a bis-epoxy compound61,73,74 Most published occurrences rely on the preparation of poly(propylene oxide) bis-cyclic carbonate-based amino-telechelic prepolymers. The challenge in this reaction is to form prepolymers of sufficiently high chain length while limiting side-reactions. To do so, several types of diamines61,74 were utilized in the synthetic process, and process parameters such as the reaction time,73,74 the reaction temperature74 and catalysis74 were investigated. In general, low molecular weights were obtained due to the excess of diamine used. When running model reactions between poly(propylene oxide) bis-cyclic carbonate and ethylene diamine (EDA),74 it appeared that the selection of the reaction temperatures was a compromise between several parameters. It was found that a temperature of 90°C allowed fast kinetics (around 100 min for the reaction to reach its maximum conversion, generally reaching a value of 90°-95°C), counter-balanced the high viscosity of the reactive mixture and avoided the extent of too many side reactions (such as urea formation by the reaction of the amine moieties onto the forming hydroxyurethanes).The use of triethylenediamine as catalyst improved the kinetics of the reaction but could not diminish the extent of those side-reactions. Moreover, trace of unreacted carbonate could still be observed. When curing the amino-telechelic prepolymers with bisphenol-A diglycidyl ether (BADGE),74 the ratio between the amine and epoxy moieties played an important role in the determination of the microstructure of the final hybrid materials. When too low NH2/Epoxy ratios were used, carbonate moieties could still be observed by infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses revealed non-homogeneous microstructures, that were attributed to an incomplete crosslinking of the material. Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 23 Increasing the NH2/Epoxy ratios led to a better crosslinking of the material as shown by tensile and swelling tests, and SEM analyses (continuous morphologies were observed). Finally, when too high amounts of diamine were incorporated into the formulation, more linear structure of H-NIPUs were obtained and higher elongations at break could be obtained through tensile tests. Similar trends were obtained with other diamines even if shorter gelation times were obtained. Shortening of the gelation times were observed when secondary amines diamines - namely diethylene triamine (DETA), triethylene tretramine (TETA) and tetraethylene pentamine (TEPA) - were used in the curing process with BADGE. This was attributed to the reaction between the inner secondary amines and BADGE, thus improving the crosslinking degree of the final materials.61,74 The impact of the NH2/Epoxy was found to have a similar trend on all kind of properties: mechanical (tensile, hardness), thermo-mechanical (by dynamic mechanical thermal analysis - DMTA) and swelling ability in solvents – namely, there is an intermediate value at which the H-NIPUs are harder, exhibit higher Young’s moduli, tensile strength, and lower elongation at break.74 In a very recent study, Ke et al. studied the influence of the synthetic process of the NIPU onto the properties of the final H-NIPUs.75 They investigated the influence of methanol as a solvent to circumvent the H-bonding formation as well as the introduction mode of the reagents while forming amino-telechelic NIPUs (in this case also, a poly(propylene oxide)-derived bis-cyclic carbonate was reacted with ethylene diamine – EDA). Dramatic impacts on the molecular weights of the NIPUs oligomers, and their behaviors when curing with BAGDE were observed. In particular, they showed that the higher the molecular weights of NIPU oligomers, the higher the gel content (>90 %) and the higher the Young’s modulus and the tensile strength. The introduction mode of the NIPU monomers was of extreme importance, especially when using methanol as the solvent. The authors compared the obtained NIPUs obtained when adding both the monomers at the same time, having a progressive addition of the diamine onto the bis cyclic carbonate (bisCC) pre-dissolved in methanol or having a progressive addition of the bisCC onto the diamine pre-dissolved in methanol. In the first case, a rapid reaction rate was observed, but urea formed (due to the reaction between the formed urethane moieties and the unreacted amine). This result was even worse with the regular addition of bisCC into an EDA solution, due to the higher concentration of the diamine in the reactive mixture. The last mode of introduction yielded a NIPU with both the highest molecular weight of all as well as a lower kinetics of formation of urea as opposed to batch mode. It was found that it influenced the Cornille et al. exemplified an interesting example of crosslinking with a tri-functional epoxy compound.73 Quite logically, harder materials exhibited a lower swelling index and a higher degree of crosslinking was obtained when using such a curing agent. In the case of cyclic carbonate-telechelic oligo NIPUs refer to the case excess carbonate in Scheme 3), the major challenge consists in the high viscosity arising from the presence of the Chapter 1 – Part A 30 Kalinina et al. reported the copolymerization of 3-(2-vinyloxyethoxy)-1,2 propylene carbonate (VEOPC) and N-phenyl maleimide (around equimolar composition) in methylethylketone (MEK) using azobisisobutyronitrile (AIBN) as thermal initiator.86 The obtained copolymers were postfunctionalized with ethylene diamine (EDA) and hexamethylenediamine (HMDA) to form H-NIPUs that were used as coatings. They exhibited good solvent resistance, low moisture absorption but poor adhesion to metal and poor impact strength. Webster and Crain studied the copolymerization of vinyl ethylene carbonate (VEC) with vinyl esters.42 Further carbonate-amine postfunctionalization studies were performed in propylene glycol monomethyl ether. Primary amines born onto primary carbons were preferred. It was shown that the stoichiometric ratio between the cyclic carbonate moieties and the amine was of great importance for the solvent resistance, namely, the less amine was incorporated into the formulation, the lower the solvent resistance. This result was however balanced by the fact that there was a limiting value above which no further improvement was observed. This was correlated with the fact that the crosslinking reaction reaches a maximum conversion, which is a classical result in PHU chemistry. Otherwise, good gloss, pendulum hardness and impact resistance were observed for the formed coatings. Cyclic carbonate (meth)acrylate (CC(M)A) polymerization has been extensively studied and reported in the scientific literature.84 Cyclic carbonate methacrylate (CCMA) can be synthesized through many reactions pathways that have been summarized by Webster95 and Caillol.84 However, the carbonation reaction by catalytic fixation of CO2 onto glycidyl methacrylate (GMA) remains the main pathway. It is important to mention that pure CCMA alone is unstable, but stable up to 100 °C when unpurified according to Endo et al.99 This instability can still be an issue after polymerization. Therefore, there is a general agreement on the fact that the radical polymerization of glycidyl methacrylate – GMA – followed by its carbonation reaction with CO2 presents advantages with respect to the direct polymerization of CCMA - Scheme 10.100–102 Scheme 10: Different synthetic pathways towards the formation of poly(CCMA) – adapted from Endo and coworkers103 Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 31 Some research teams tried to make CCMA-containing oligomers react with amine-containing compounds to yield hydroxyurethane. Kihara et al. thus functionalized CCMA-containing oligomers with butylamine, benzylamine, cyclohexylamine and dibutylamine.99 The authors showed that an excess of amine as opposed to the CCMA units was necessary for reaching full conversion. Secondary amines barely reacted due to steric hindrance. Finally, when a diamine such as hexamethylene diamine (HMDA) was introduced with a 1:1 ratio, gelation occurred after 1.5 h in dimethylsulfoxide (DMSO). The infrared (IR) analysis revealed that the reaction was not complete since traces of cyclic carbonate and amine could be observed, trapped in the polymer network. The obtained film was reported as both hard and flexible. The same team published100 the post-functionalization of a copolymer of CCMA and GMA 0:70, Mn=000 g/mol, Ɖ=.5 via an aminolysis reaction with butylamine. In this case, careful attention between the reactivity of the oxirane and the carbonate moieties should be paid. If an acidic treatment was performed prior to aminolysis, then the oxirane moieties would open and the amine would selectively react onto the carbonate moieties. The obtained polymers displayed increased solubility in water and methanol, which was not the case before functionalization with the amine. When the aminolysis was performed before the acidic treatment, crosslinking through an epoxy-like mechanism occurred and made the final polymer insoluble. Finally, in 2010, Jana et al. used atom transfer radical polymerization (ATRP) in order to synthesize homopolymers, triblock copolymers and terpolymers bearing CCMA moieties in pendant chains.96 They post-functionalized the CCMA moieties with 2-phenylethylamine in order to modify the solubility and wettability properties of the obtained polymers. The reaction was carried out in dimethylformamide (DMF) and different degrees of functionalization were achieved. Only 40 % of functionalization was enough to make the polymers soluble not only in polar aprotic solvents such as DMF and DMSO but also in more common solvents such as acetonitrile (ACN) and tetrahydrofuran (THF). Higher extents of functionalization (~90 %) allowed solubilizing the polymers in solvents such as chloroform. Finally, the films’ properties were studied, and it was found that functionalizing the CCMA-containing polymers helped transitioning from a quite brittle to uniform, transparent and continuous films when casting them onto glass substrate using DMF as solvent. The water contact angle, while strongly depending on the polymer composition, was shown to continuously increase with the degree of functionalization in spite of the concomitant appearance of hydroxyl groups. This was attributed to the effect of the hydrophobic side group of the 2phenylethyl amine used. This suggests that tuning of the hydrophilic/hydrophobic balance of the final polymer could probably be achieved by changing the amine. Such technologies were also patented, notably by Figovsky et al.104,105 who claimed the formation of coatings based on the curing reaction between cyclic carbonate methacrylate (CCMA) and amines. They also mixed those technologies with the previously described Epoxy-NIPUs obtaining interesting mechanical properties with an average tensile strength of 40 MPa and an average elongation at break of 55 % depending on the formulation.104 Iwamura and coworkers also patented aminolysis of cyclocarbonate-based oligomer to produce coating for automotive applications.106 Chapter 1 – Part A 32 Interestingly, CCMA has been incorporated into formulations for emulsion copolymerization. Yang et al.107 patented an interesting process in which different latexes were prepared, some bearing CCMA moieties and others bearing amines. It was shown that those latexes were able to crosslink. The CCMA-functionalized latexes were capable of forming films and further addition of polyamine induced crosslinking. When the CCMA-functionalized and amine-functionalized latexes were blended together, the formed film could be crosslinked by curing at room temperature during 24 h. These films exhibited gel contents around 60 % in acetone, as well as good water resistance. Other patents from BASF disclosed the use of CCMA-functionalized coatings that were able to crosslink according to the same mechanisms described before using primary amine agent for paint applications.108–110 Finally, the case of cyclic carbonate acrylate (CCA) has also been studied, although to a lesser extent than for CCMA. The synthetic routes towards the formation of CCA are very similar to those to synthesize CCMA.111–114 Yields of 85% were obtained through the carbonation of glycidyl acrylate with CO2 at 60°C in the presence of inhibitors (4-methoxyphenol).114 The reaction conditions as well as the purification steps are of extreme importance since the monomer can suffer from sidereactions or even start polymerizing at temperatures as low as 40 °C. Homopolymerization of CCA in solution usually led to insoluble polymers, which was explained because of the transfer reaction from the carbonate ring with proton removal and radical recombination.99,115 The copolymerization with 2-ethylhexyl acrylate was found to be a solution to yield soluble polymers in benzene, chlorinated solvent such as dichloromethane and tetrahydrofuran.115 Photopolymerization was also implemented.116,117 To the best of our knowledge, only one example has been reported in which the carbonate moieties were functionalized with butylamine.115 Kinetic studies on model molecules showed that bulk processes were faster than solution processes.115 3.2.2. (Hydroxy)urethane methacrylates – (H)UMAs (Hydroxy)urethane methacrylates ((H)UMAs) are short oligomers (usually dimers or trimers) synthesized by aminolysis of a cyclic carbonate and an amine, one of them bearing at least one methacrylate moiety. A typical isocyanate-free synthetic approach consists in the formation of a diol, which is subsequently functionalized into a dimethacrylate component (Scheme 11), but more complex structures have also been designed.21,118,119 Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 33 Scheme 11: Formation of UMAs via the aminolysis of ethylene carbonate followed by subsequent functionalization (H)UMAs were originally designed to be used as reactive diluents. Such compounds can for example be employed in ultraviolet (UV)-curable coatings, which are gaining interest for their fast curing and low energy consumption.120 Figovsky et al. reported UV-curable concrete floor coatings able to cure instantly.64 A general composition of a UV-curable coating is a mixture of photoinitiator, oligomer and reactive diluent, the latter being used to decrease the viscosity of the global mixture, while polymerizing in the crosslinking reaction to form a 3D-network. According to Wang and Soucek, mono-functional reactive diluents usually lead to a decreased modulus and increased ductility whereas biand/or multi-functional reactive diluents have the opposite effect.118 It was also found that the introduction of acrylic moieties into the (H)UMAs was a suitable method for overcoming the yellowing effect of the PHU caused by sunlight.105 Due to their versatile composition, and the diversity of components that can be used for copolymerization purposes, UV-curable formulations can find other applications such as biomedical, for instance via the development of injectable liquids, paste or gels (dental composite applications being a potential example).119,121 Assumption and Mathias published in 2003 a method for synthesizing isocyanate free urethane methacrylates UMAs via the ring opening aminolysis of ethylene carbonate with various amines.119 Hexamethylene Diamine (HMDA), 3-amino-1-Propanol and 2,2-dimethyl-1,3-propanediamine were used, and methacrylic anhydride was utilized in the functionalization step in order to catalytically react with all the hydroxyl groups - Figure 7. The kinetics of the radical photopolymerization of the formed UMAs was measured and extremely fast polymerization rates (plateauing conversion after 100 s reaction time) were obtained. An immediate auto-acceleration was noticed and the fastest polymerization rates were reached after 4 to 5s. The reaction rate was found to strongly depend on the monomer structure of the UMA. In particular, the presence of H-bonding, allowing preassociation effects between the monomers enhanced the polymerization rates, which is in accordance with the work of Jansen et al.92 Wang and Soucek118 synthesized a series of similar reactive diluents following a similar procedure. They varied the structure of the cyclic carbonate Chapter 1 – Part A 34 compound to introduce an additional methyl moiety. 2-(methacryloyloxy)ethyl 2- (methacryloyloxy)ethylcarbamate (EOAED), 2-(methacryloyloxy)ethyl 3- (methacryloyloxy)propylcarbamate (POAED), and 1-(methacryloyloxy)propan-2-yl 3- (methacryloyloxy)propylcarbamate (POAPD) were hence synthesized by functionalization with methacrylic anhydride - Figure 7. The formed reactive diluents were tested in a formulation containing an oligo polyester. It was observed a general increase of tensile strength and elongation at break when using the non-isocyanate version of the reactive diluents. In more details, and as already observed in the case of Epoxy-NIPUs, there was an optimum concentration of reactive diluent to be introduced in the formulation. Below this value, tensile strength and elongation at break increased with the reactive diluent content. Above it, they usually decreased. Glass transition temperatures (Tgs), -transition temperatures Ts and gel contents also increased with the reactive diluent content, due to the higher crosslinking density. One drawback is the water sensitivity since the water absorption was found to increase with the increase in reactive diluent content. This was attributed to the increase of ester-urethane group concentration, a polar group capable of interacting with water. Finally, the reactive diluents increased the impact resistance. Figure 7: Reactive diluents prepared by Assumption et al.119 and Wang et al.118 Similar types of multi-functional hydroxyurethane methacrylates (HUMAs) were proposed by Biernat and Rokicki in 2005.21 The synthetic approach relies on the aminolysis reaction of glycerol carbonate with a diamine. The formed hydroxyurethane quadriols (3 isomers can be obtained) were subsequently modified by reacting with methacryloyl chloride or methacrylic anhydride to form the corresponding quadrimethacrylate - Scheme 12. Various amines could be used for the synthesis, including 1,3-diaminopropane, 1,2-diaminoethane and isophorone diamine (IPDA). Amino-alcohols were also used and yielded trifunctional urethane methacrylates. Scheme 12: Multifunctional HUMAs via functionalization of glycerol carbonate-based quadriols by methacryloyl chloride according to Biernat and Rokicki.21 (Note that DMAP stands for 4-Dimethylaminopyridine) Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 35 Following a similar approach, the same authors21 used carbonatedBisphenol-A Diglycidyl Ether (BADGE) in order to synthesize multifunctional HUMAs. This process was different from the previously described one in the sense that a bis cyclic carbonate compound was used instead of a mono cyclic carbonate. The quadri-functionality was brought through the reaction with an aminoalcohol that was further modified with methacryloyl chloride to yield the final products - Scheme 13. Scheme 13: Multifunctional HUMAs via functionalization of carbonated-BADGE-based quadriols by methacryloyl chloride according to Biernat and Rokicki.21 (Note that DMAP stands for 4-Dimethylaminopyridine) The synthesized resins exhibited high flexural strength after curing. The BADGE-based resins had superior toughness than a reference resin for dental compositions. This high flexural strength in combination with a low viscosity make such components extremely interesting reactive diluents. Due to the high crosslinking density, a high hardness is usually obtained. Attention has recently been paid towards the development of new kinds of materials for 3D – printing purposes.122 The ability of (Hydroxy)urethane Methacrylates - (H)UMAs to photopolymerize makes them perfect candidates for such application. To the best of our knowledge, two research teams have recently published isocyanate-free pathways to develop 3D-printable resins. The team of Chen proposed two possible polymerization pathways for the design of 3Dprintable resins based on the formation of a diurethane adduct via the aminolysis of a vinylic- (or methacrylic-) 6-membered cyclic carbonate monomer with a diamine. The authors suggested two polymerization pathways: a first generation of adducts reacting in a radical photoinduced process whereas a second generation which proceeded through a thiol-ene route - Scheme 14. 123,124 Chapter 1 – Part A 36 Scheme 14: 3D-printable HUMAs based on a 6-membered cyclic carbonate diurethane adducts, further polymerized either by radical photopolymerization (1st generation)123 or via thiol-ene chemistry (2nd generation)124 – adapted from Pyo et al. In the first generation, the diurethane adduct containing methacrylic moieties was formed first and then crosslinked via an ultraviolet (UV)-induced process to yield the final material. The obtained products were amorphous and stable up to temperatures higher than 200 °C. They were 3D-printed in a continuous optical printing system using a layer by layer polymerization methodology. Materials of tunable stiffness with smooth contours could thus be designed. In the second generation, a vinylic cyclic carbonate was copolymerized also in a UV-induced process with bito quadri-functional thiols. The biocompatibility of these materials for potential biomedical applications was also evaluated. (Hydroxy)urethane Methacrylates - HUMAs synthesized through the reaction of a series of diamines with two equivalents of cyclic carbonate methacrylate (CCMA) in a bulk process for 3D-printing purposes.125 . The HUMAs were further copolymerized with 4methacryl-oylmorpholine (ACMO) with the help of a photo-initiator. The structure of the diamine was found to have a great influence on the viscosity of the resulting acrylic resin formulation, but all of them remained within industrially acceptable viscosity ranges. Short and flexible etheramines were highlighted as preferable reactive diluents since they offered a compromise between low viscosity and very good mechanical performance (Young modulus of 3600 MPa, and tensile strength of 85 MPa were measured in the case of 1,8-diamino-3,6-dioxaoctane-based HUMAs). Multifunctional HUMAs obtained by functionalization of the pendant OH groups with methacrylate anhydride were also used leading to an increase in thermo-mechanical properties (Young modulus of 4200 MPa instead of 3600 MPa and a Tg of 173 °C instead of 86 °C were obtained). There are two examples of the use of urethane methacrylates (UMAs) in waterborne systems.126,127 The UMAs were prepared via the aminolysis reaction of ethylene carbonate with a series of aliphatic amines prior to the functionalization with methacrylic anhydride - Scheme 15.126 This process allowed to target different hydrophobicity level for the reactive diluent, that were subsequently copolymerized with MMA/BA in a seeded semibatch emulsion polymerization in Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 37 monomer starved conditions, with a solids content of 30 wt%. The same year, the same team investigated more deeply the case of BEM (butyl-based UMA, a=3 in Scheme 15).127 The emulsion polymerization process (batch vS semibatch mode) as well as the particle morphology (homogeneous vS core-shell) and the location and concentration of BEM within the particle (in the core or in the shell) in terms of film properties were the focus of the study. Those works are reviewed in more details in the Part B of this Chapter dealing with water-based NIPUs. Scheme 15: Preparation of mono-functional UMAs of different hydrophobicity according to Meng et al.126 3.2.3. Unsaturated NIPU-prepolymers: Poly(hydroxy)urethane methacrylates – P(H)UMAs 3.2.3.1. H-NIPUs via radical polymerization  Radical reactive telechelic polyurethanes Longer isocyanate-free urethane methacrylates UMAs (oligoUMA) were designed by Ochiai and Utsuno by functionalizing oligomeric polyurethane diols with glycidyl methacrylate (GMA).128 The polyurethanes (PUs) originate from a transurethanization process yielding the OH-telechelic oligomers. The ring opening of GMA did not proceed to full conversion so that an excess was employed for maximizing the extent of functionalization. The oligoUMAs were further copolymerized with methyl acrylate (MA) (in a ratio 50:50 in reactive moieties) in dimethylformamide (DMF) at 60 °C using AIBN as thermal initiator for 24 h - Figure 8. The formed polymer almost instantaneously became a gel, which was insoluble in any organic solvent. The formed polymer was composed of a hard PU segment and soft poly(methyl methacrylate) segments. After thermal treatment in the DSC, the PU and the acrylate phase became miscible and a single Tg of 34 °C was obtained. The Tg was found to be higher than both the native PU and poly(MA), a phenomenon that was attributed to the restricted motion of the polymer chains in the 3D network. Chapter 1 – Part A 38 Figure 8: Copolymer from oligoUMA and MA according to Ochiai et al.128 The growing interest in the development of a more sustainable chemistry is pushing the research community to develop more environmental friendly products. In this purpose, Han et al. developed a new kind of poly(ester-urethane)s that were functionalized with the bio-based itaconic acid - Scheme 16.129 NIPU pre-polymers were synthesized by ring opening of ethylene carbonate with various diamines. The formed diols were then reacted with an excess of itaconic acid and subsequent polycondensation led to radical reactive telechelic oligo(Ester-Urethane)s. The latter were further cured by a UV-induced process with dimethylpropionic acid (DMPA). Gel contents in the range 80 to 88 % were obtained in acetone. The tensile strength depended on both the chain length of the diamine and the crosslinking density, with the best mechanical properties obtained in the case of putrescine-based oligo(Ester-Urethane) (Young modulus of 52 MPa, a tensile strength of 2.5 MPa and an elongation at break of 33 %). Scheme 16: Fully-bio-based HUMAs functionalized by itaconic acid according to Han et al.129  Hydroxyl-group functionalization The group of Endo functionalized the pendant OH groups of isocyanate-free oligo(hydroxyurethane)s (oligoPHUs)130 by reacting 2-methacryloyloxyethyl isocyanate with a carbonated Bisphenol-A Diglycidyl Ether (BADGE)-based oligoPHU - Scheme 17. The temperature Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 39 of the urethanization should be controlled to avoid polymerization of the methacrylate moieties. Therefore, room temperature was preferred and a full conversion could be obtained. . The advantage of functionalizing pendant OH groups relies on the fact that the degree of functionalization can be controlled. When functionalizing the oligoPHU with 1 eq. of the isocyanate compound with respect to the hydroxyl groups in the oligomer, successful copolymerization with Hydroxyethylmethacrylate (HEMA), methyl methacrylate (MMA) and N-isopropylacrylamide (NIPAM) was achieved in dioxane. In all cases, the viscosity of the polymerization mixture increased during the reaction until the formation of insoluble gels. Tgs lower than or identical to that the corresponding polymethacylates were measured, suggesting that the distance between crosslinking nodes was sufficiently long to allow mobility of the incorporated PHU chains. It should however be mentioned that this synthetic process, despite being extremely interesting, is unfortunately not fully isocyanate-free, which can seem counterbalancing the isocyanate-free process formation of the native oligoPHU. Scheme 17: Functionalization of the pendant OH-groups of carbonated BADGE-based oligoPHUs according to Endo and coworkers130 A very recent example, from Caillol and coworkers, describes the synthesis of hydroxyurethane Methacrylate (HUMA) capable of crosslinking in a thermal pathway only, without using any initiator.131 A carbonated poly(propylene oxide) diglycidyl ether (shortened PPOBC) was reacted with ethylene diamine (EDA) or with (ethylenedioxy)diethylamine (EDR) to form a diamino-telechelic compound, which was further functionalized with the help of ethylene carbonate. The formed diol was then modified with methacrylic anhydride into the corresponding HUMA as described in Scheme 18. The formed HUMAs were further homopolymerized or crosslinked with either benzyl methacrylate or poly(ethylene oxide) bisphenol A dimethacrylate. Chapter 1 – Part A 46 3.3. Other Hybrid-NIPUs In addition to epoxy and (meth)acrylic NIPUs, new types of hybrids have appeared in the scientific literature. Herein silicon containing H-NIPUs and hybrids combining biopolymers with NIPUs are discussed. 3.3.1. Si-containing H-NIPUs Silicon and more specifically siloxane containing H-NIPUs have been prepared in order to confer new kinds of properties to the hybrids. Siloxane moieties can be incorporated through various synthetic means, either in the inner backbone of the final linear NIPU or by acting as crosslinking agents bearing cyclic carbonate or amine moieties, hence yielding a branched or cross-linked architecture. Both routes will be described. 3.3.1.1. Sicontaining linear H-NIPUs with inner siloxane backbones Endo and coworkers and Hanada et al. introduced in 2014 a PHU containing siloxane in the inner backbone of the polymer material.133,134 Their purpose was to achieve improved water resistance and flexibility. They designed a 1 pot-2 steps process in which Bisphenol-A Diglycidyl Ether (BADGE) was carbonated by CO2 fixation prior to reacting with the siloxane containing diamine - Scheme 21. Propylene glycol methylether acetate (PGMAC) was a suitable solvent to obtain the final PHU in high yields. When comparing the siloxane containing NIPUs with a classical NIPU made of carbonated BADGE and dodecanediamine, it was found that the higher the siloxane content, the higher the solubility of the formed products in solvents of low polarity such as Et2O. Water contact angle and flexibility increased as the siloxane content increased. The materials had low glass transition temperatures (1 and 26 °C as opposed to 40 °C with dodecanediamine). Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 47 Scheme 21: PHU containing siloxane-based inner backbone according to Endo and coworkers133 As far as we know, only one example of siloxane-containing bis-cyclic carbonate compounds has been patented. This work was performed by the team of Hanada135 and preceded the patent on diamino-polysiloxane macromomers.133 An example of the synthesized bis-cyclic carbonate compounds in provided is Figure 10. The authors targeted applications such as thermal recording medium, artificial leather, thermoplastic polyolefin resin skin material and weather strip material. The obtained bis-cyclic carbonates were further converted by reacting with diamines (hexamehthylene diamine (HMDA), bis-aminopropylpiperazine, and xylylenediamine were used). The number average molecular weights were in the range 30000-40000 g/mol depending on the siloxane-containing bis-cyclic carbonate and the diamine used. Tensile strengths of around 24 to 35 MPa and elongations at break in the range of 15 to 83 % were obtained, witnessing the possible tuning of the material properties. Figure 10: Example of a siloxane-containing bis-cyclic carbonate macromonomer as patented by Hanada et al.135 Figovsky et al. used a siloxane-containing macromonomer in their Epoxy-Amine H-NIPU systems.136 They claimed the synthesis of nanostructured H-NIPUs that were constituted by epoxyfunction, cyclic carbonate, amine-functional and (meth)acrylate components. Among them, at least one epoxy, amine or (meth)acrylate contained alkoxysilane moieties. The formed polymers crosslink upon curing at ambient conditions by means of atmospheric moisture, yielding nanostructured materials without the need of using water embedding or addition of nanofillers. The materials exhibited improved abrasion resistance and higher impact resistance and flexibility compared with a conventional epoxy resin siloxane based material that was used as a reference. Chapter 1 – Part A 48 3.3.1.2. Sicontaining branched or crosslinked H-NIPUs with outer siloxane backbones Another important pathway is the reaction of siloxane or Si-containing reagents bearing cyclic carbonate or amine moieties.  Si-containing reagents bearing amine moieties Figovsky and coworkers developed thermostable resins with Si-containing amine components using multiaminosilane agents as hardeners in the curing process of their Epoxy-PHU H-NIPU process.137 The commercially available -aminopropyltriethoxy silane was hydrolyzed to yield the multiaminosilane curing agent. Similar dendro-silanes containing aromatic units were introduced into epoxy and cyclocarbonate resins. Once introduced into the resins, the alkoxy groups were hydrolysed by the humidity of either the air or that of the surface of the substrate. The newly built silanol-hydroxyl groups reacted with the surface hydroxyl groups and forms strong bonds, making them good adhesion promoters.136 Scheme 22: Multiaminosilane synthesis according to Figovsky and coworkers137 Another example is the work Narayan and coworkers138 who synthesized oligo(siloxaneurethane) through the reaction of 3-amino-propyldimethylethoxysilane (MEC), 3aminopropyldiethoxymethylsilane (DEC) and (3-amino-propyltriethoxysilane) (TEC) with ethylene carbonate. The formed adducts underwent a spontaneous rearrangement by condensation of the alkoxysilane groups with the hydroxyl functions resulting from the ring opening of the ethylene carbonate as depicted in Scheme 23. Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 49 Scheme 23: Oligo(siloxane-urethane) formation from aminopropyl alkoxysilanes according to Narayan et al.138 The same team reported the possibility to tune the condensation process for those siloxaneurethane adducts containing two alkoxy groups.139 In anhydrous condition, the monomer formed a hyperbranched structure starting from an AB2-type unit. This was not the case under acidic condition in which a linear structure was formed. Scheme 24: Condensation process of the DEC-propylene carbonate adduct according to Nerayan et al.139 Chapter 1 – Part A 50  Si-containing reactants bearing cyclic carbonate moieties Early work in this field was published by Wnek and coworkers in 1994, where they reported the synthesis of polysiloxane polymers bearing cyclic carbonate side chains140 and studied the influence of the presence of the side carbonate on the dielectric properties and ion conductivity for battery applications. No post-functionalization of the carbonate moieties was carried out. Liu et al.141 published in 2017 the synthesis of cyclic carbonate containing polysiloxane compounds for the production of coatings with improved water resistance. Those adducts were further reacted with a stoichiometric amount of diamines, at 100 °C in a mold for 10 h to yield polysiloxane-PHU. Different degrees of carbonation were tested in order to tune the concentration of hydroxyurethane moieties in the final material - Scheme 25. Differential scanning calorimetry (DSC) analyses revealed only a single glass transition temperature that ranged from 3 to 60°C depending on the amine and the degree of carbonation of the polysiloxane, indicating that no phase separation occurred. The degree of carbonation, namely the extent of crosslinking, influenced the mechanical properties by increasing the tensile strength and Young modulus, but lowering the elongation at break. The same behavior was observed when increasing the amount of cycloaliphatic moieties of the diamine. Scheme 25: Polysiloxane-PHU H-NIPUs from cyclic carbonate-containing polysiloxanes according to Liu et al.141 However, and despite the acceptable swelling indexes in water (from 3 to 22 wt%), the water resistance decreased with the degree of crosslinking. This was attributed to the increase in hydroxyl moiety concentration within the formed material. In this regard, introducing more hydrophobic Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 51 diamines (especially those containing cycloaliphatic rings) was a satisfactory solution to both decrease the swelling in water as well as obtaining materials with higher Young moduli and tensile strengths.  Si-telechelic PHU prepolymers To the best of our knowledge, only one example of reactive telechelic-oligoPHUs, involving Sicontaining chain ends, has been reported in the scientific literature. This is not surprising as the formation of well-defined reactive telechelic PHUs is still one of the major unsolved issues in this chemistry. This work was undertaken by the team of Caillol who published in 2018 the synthesis of sol-gel hybrid-poly(hydroxyurethane)s.142 Their synthetic process consists in end-capping difunctional PHU monomer (namely bis cyclic carbonates or diamines) with siloxane-containing amine or mono cyclic carbonate. A subsequent sol-gel process allowed for the latter crosslinking of the siloxane homotelechelic PHU chains - Figure 11. A very high thermal resistance, with Td5% higher than 300 °C was obtained. The presence of a rubbery plateau with a modulus in the order of magnitude of 107 Pa after the alpha transition in the Dynamic Mechanical Thermal Analysis (DMTA) measurements showed that the polymer was crosslinked, which was confirmed by the gel content (90 %) measured by extraction of the soluble polymer with THF. Figure 11: Formation of Hybrid PHU-siloxane thermosets via the synthesis of siloxane homo-telechelic oligoPHUs – adapted from Caillol and coworkers142 Chapter 1 – Part A 52 3.3.1.3. POSS-containing H-NIPUs Another possibility to introduce Si-containing compounds into NIPUs is through the use of polyhedral oligomeric silsesquioxanes (POSS). This compound has been used to provide novel properties into materials.143,144 Mechanical properties, thermal stability, water tolerance or dielectric properties were shown to be positively influenced when POSS was incorporated into polymer matrixes. Liu et al. incorporated POSS into PHU coatings containing gallic acid145 or rosin143 - Scheme 26. In the first example, gallic acid-based epoxy resin was treated by catalytic fixation of CO2 to form the tetracarbonate. The carbonate was reacted with various diamines and also modified with epoxidized-POSS components in a similar process than the Epoxy-NIPU H-NIPU. The introduction of POSS increased the water resistance of the NIPUs, without being detrimental to other properties such as impact resistance, pencil hardness or flexibility. In general, the increase of the POSS loading induced an increase in the rigidity of the material (some were more brittle) and thermal properties (Td50% over 300 °C by thermo gravimetruc analyses - TGA), which was attributed to the increase in the crosslinking density. A similar study was performed with rosin-based carbonate compounds, with a slight difference consisting in the fact that both epoxidized-POSS and carbonated-POSS were used in the formulation while reacting with a diamine. Similar enhancements in the properties of the composites were observed upon introduction of POSS into the NIPU formulations. For similar POSS contents, the epoxy-POSS yielded materials with better water resistance than the carbonated-POSS, which was attributed to the formation of urethane linkages. This positive impact of the incorporation of POSS into NIPU formulations on the mechanical properties was confirmed by Blattmann and Mülhaupt.146 They targeted the development of a solvent-free process for the production of POSS-containing NIPUs and investigated the pot life and gel times of different formulations while incorporating carbonatedPOSS. Due to the very high functionality, the curing with diamine led to extremely short pot life and gel time (hundreds of seconds). Because of the improvement in processability, without being too detrimental for mechanical properties, reactive diluents based on carbonated glycidyl ethers were utilized - Figure 12. Superior mechanical properties, with Young moduli of exceptional values (until 4000 MPa) could thus be obtained. Unfortunately, no enhancement in terms of water resistance was observed, which can be explained by the presence of hydrophilic hydroxyurethane moieties. Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 53 Scheme 26: POSS-containing NIPUs from gallic acid (left) and rosin (right) according to Liu et al.143,145 Figure 12: POSS-containing NIPUs according to Blattmann and Mülhaupt146 Chapter 1 – Part A 54 3.3.2. Biopolymer-containing NIPUs Biopolymers, defined as naturally occurring polymers, are gaining an increasing interest because they are renewable compounds leading towards more sustainable and environmental-friendly materials. These polymers do not need to be synthesized, as opposed to the epoxy and acrylic resins described above. By means of wise chemical modification, the incorporation of such compounds can significantly broaden the final properties of the formed materials. The biopolymers incorporated in NIPUs include natural rubber, and derivatives of wood resources, namely tannin, lignin and cellulose. 3.3.2.1. Natural Rubber H-NIPUs In 2017, the team of Pilard reported on the use of natural rubber (NR) for the synthesis of NIPUs.147 Their process consisted in degrading NR in oligo-isoprene, that were further functionalized in diaminoof bis cyclic carbonate compounds - Scheme 27. Different chain lengths of the functional oligo-isoprene were targeted (1000 and 2000 g/mol) and tested in a subsequent polymerization with bis-cyclic carbonates or diamines. The advantage of degrading the NR was not only to get a better control of the chain length, but also to have oligo-isoprene that can be dissolved in solvents such as THF and dioxane, thus allowing reactions in solution to form NIPUs. Dioxane was found to be the most suitable solvent since temperatures as high as 100 °C were necessary for the reaction to proceed. Bulk polymerization was also performed. No formation of by-products such as urea or amides was observed. Interestingly, by playing with the process’ conditions and the carbonate to amine ratio, a 100 % conversion could be achieved in the case of carbonate-telechelic NRs. Unfortunately, solubility issues made the characterization by SEC difficult. Low glass transition temperatures were obtained, ranging from -58 to -30 °C. Noteworthy, the longer the chain the lower the Tg, which was attributed to the higher flexibility of the polymer chains by the increasing amount of oligo-isoprene incorporated. Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 55 Scheme 27: Natural Rubber-based NIPUs (NR-based NIPUs) – adapted from the work of Pilard and coworkers147 3.3.2.2. Lignin and tannin-based H-NIPUs  Lignin-based H-NIPUs The use of lignin is gaining momentum in the field of the development of novel polymer materials. Lignin nowadays is considered as the main resource for the synthesis of bio-aromatic monomers. It constitutes 20 to 25 wt% of wood with a world production from the pulp industry reaching 50 million tons/year.148 Because this resource is low cost and is not in competition with the food industry, substantial efforts are directed towards its valorization. This complex biopolymer however has to be degraded in smaller building blocks prior to using it. Mostly polyols are formed, which made lignin extremely popular in the PU chemistry since it could directly react with isocyanate compounds.149–152 However, quite scarce examples of the use of lignin can be encountered in the literature. Among them, Lee and Deng published in 2014 an example in which the phenolic units of lignin were used in combination with a siloxane-modified carbonated soybean oil for the design of lignin-based NIPUs -Scheme 28.153 During the polymerization process, the condensation of siloxane moieties, yielding –Si-O-Sigroups, occurred. 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(147) Jaratrotkamjorn, R.; Nourry, A.; Pasetto, P.; Choppé, E.; Panwiriyarat, W.; Tanrattanakul, V.; Pilard, J. F. Synthesis and Characterization of Elastomeric, Biobased, Nonisocyanate Polyurethane from Natural Rubber. J. Appl. Polym. Sci. 2017, 134 (42). (148) Cramail, H.; Bizet, B.; Lamarzelle, O.; Durand, P.-L.; Hibert, G.; Grau, E. Bio-Sourced Polymers: Recent Advances. In Advanced Green Chemistry; World Scientific Publishing Company (WSPC) ./ Imperial College Press (ICP), Ed.; 2019. (149) Laurichesse, S.; Avérous, L. Chemical Modification of Lignins: Towards Biobased Polymers. Prog. Polym. Sci. 2014, 39 (7), 1266–1290. (150) Silva, E. A. B. da; Zabkova, M.; Araújo, J. D.; Cateto, C. A.; Barreiro, M. F.; Belgacem, M. N.; Rodrigues, A. E. An Integrated Process to Produce Vanillin and Lignin-Based Polyurethanes from Kraft Lignin. Chem. Eng. Res. Des. 2009, 87 (9), 1276–1292. (151) Hatakeyama, H.; Hirogaki, A.; Matsumura, H.; Hatakeyama, T. 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Polyurethanes from Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 69 Hydrolysable Tannins Obtained without Using Isocyanates. Ind. Crops Prod. 2014, 59, 329–336. (157) Thébault, M.; Pizzi, A.; Essawy, H. A.; Barhoum, A.; Van Assche, G. Isocyanate Free Condensed Tannin-Based Polyurethanes. Eur. Polym. J. 2015, 67, 513–526. (158) Thébault, M.; Pizzi, A.; Santiago-Medina, F. J.; Al-Marzouki, F. M.; Abdalla, S. Isocyanate-Free Polyurethanes by Coreaction of Condensed Tannins with Aminated Tannins. J. Renew. Mater. 2017, 5 (1), 21–29. (159) Fleischer, M.; Blattmann, H.; Mülhaupt, R. Glycerol-, Pentaerythritoland TrimethylolpropaneBased Polyurethanes and Their Cellulose Carbonate Composites Prepared via the NonIsocyanate Route with Catalytic Carbon Dioxide Fixation. Green Chem. 2013, 15 (4), 934–942. (160) Nanotech Industries. Green PolyurethaneTM https://nanotechindustriesinc.com/GPU.php (accessed Sep 17, 2019). Chapter 1 – Part A 70 6. Shortened forms ACMO: 4-methacryl-oylmorpholine ACN: Acetonitrile AIBN: Azobisisobutyronitrile ATRP: Atom Transfer Radical Polymerization BADGE: Bisphenol-A Diglycidyl Ether bisCC: bis cyclic carbonate CC(M)A: Cyclic carbonate (meth)acrylate CMR: Carcinogenic, mutagenic, reprotoxic CO2: Carbon Dioxide CSO: Carbonated Soybean Oil DBTDL: Dibutyltin dilaurate DCC: N,N′-Dicyclohexylcarbodiimide DCU: 1,3-Dicyclohexyl urea DEC: 3-aminopropyldiethoxymethylsilane DETA: Diethylenetriamine DMAc: Dimethylacetamide DMAP: 4-Dimethylaminopyridine DMF: Dimethylformamide DMPA: Dimethylproprionic acid DMSO: Dimethylsulfoxide DMTA: Dynamic Mechanical Thermal Analysis DSC: Differential Scanning Calorimetry EDA: Ethylene Diamine EDR: (ethylenedioxy)diethylamine EDGE: Ethylene Glycol Diglycidyl Ether EOAED: 2-(methacryloyloxy)ethyl 2-(methacryloyloxy)ethylcarbamate FTIR: Fourier Transformed Infrared GMA: Glycidyl Methacrylate HCl: Hydrochloric acid HEMA: Hydroxyethylmethacrylate HMDA: Hexamethylene Diamine H-NIPU: Hybrid-Non Isocyanate Polyurethane HUM: Hydroxyurethane Modifier HUMA: Hydroxyurethane Methacrylates IPDA: Isophorone Diamine IPN: Interpenetrating Network IR: Infrared MA: Methyl Acrylate MEC: 3-amino-propyldimethylethoxysilane MEK: Methylethylketone MMA: Methyl Methacrylate NIPAM: N-isopropylacrylamide Hybrid – Non Isocyanate Polyurethanes (HNIPUs) – A Pathway towards a Broad Range of Novel Materials 71 NIPU: Non Isocyanate Polyurethane NIPUrea: Non Isocyanate Polyurea NMR: Nuclear Magnetic Resonance NR: Natural rubber oligoPHUs: oligo(hydroxyurethane)s oligoUMA: Oligomers of urethane methacrylate OVE: (2-0xo-1,3-dioxolan-4-yl) methyl vinyl ether PGMAC: Propylene glycol methylether acetate PHU: Poly(hydroxyurethane) P(H)UMAs: Poly(hydroxyl)urethane methacrylates POAED: 2-(methacryloyloxy)ethyl 3-(methacryloyloxy)propylcarbamate POAPD: 1-(methacryloyloxy)propan-2-yl 3-(methacryloyloxy)propylcarbamate POSS: Polyhedral oligomeric silsesquioxanes PPOA: poly(propylene oxide) bis-acrylate PPOBC: poly(propylene oxide) diglycidyl ether PU: Polyurethane PUU: Polyurethane-urea SEC: Size Exclusion Chromatography SEM: Scanning Electron Microscopy TBD: Triazabicyclodecene TEC: 3-amino-propyltriethoxysilane TEM: Transmission Electron Microscopy TEDA: Triethylene diamine TEPA: Tetraethylene pentamine TETA: Triethylenetetramine Tg: Glass Transition Temperature TGA: Thermo gravimetric analysis TGDEC: Carbonated resin based on triethylene glycol diglycidyl ether THF: Tetrahydrofuran TMPTA: trimethylolpropane tris-acrylate TREN: Tris(2-aminoethyl)amine Tα: -transition temperatures VEC: Vinyl ethylene carbonate VEOPC: 3-(2-vinyloxyethoxy)-1,2 propylene carbonate UMAs: Urethane methacrylates UV: Ultraviolet Chapter 1 – Part B 78 Scheme 2: Homogeneous water-based systems according to Sardon et al.49 The copolymer structure (balance between hard and soft segments) was tuned by varying the monomer ratio. High conversions (>98%) and polymers with molecular weights ranging from 15 to 16 kDa were obtained. Interestingly, the polymers exhibited melting behaviors in DSC in the range from 27 to 33°C. The extent of crystallinity was found to be dependent on the ratio between the PEG-based carbonate (crystalline) and the hexanediolbased monomer. The glass transition temperatures were found to lie around -55°C. 2.2. Modification of NIPUs synthesized in organic solvents Detrembleur et al. also played on the chemical structure of the NIPU to influence its final hydrolytic behavior. They introduced imine linkages within the polymer backbone in order to induce acid-sensitivity.50 To do so, they reacted propargylic alcohol with carbon dioxide to obtain an unsaturated cyclic carbonate. The subsequent aminolysis of this monomer with a diamine in DMF yielded a diurethane pre-polymer that further reacted with a diamine yielding the corresponding poly(urethane–co–imine), also shortened PUIs –Scheme 3. Scheme 3: Imine-containing NIPUs – adapted from Detrembleur et al.50 Water-based Non Isocyanate Polyurethanes-Polyureas (NIPUUs) 79 The successful synthesis of the PUIs was found to highly rely on the use of a good Lewis acid that not only catalyzes the polymerization, but also acts as a dehydrating agent, thus shifting the chemical equilibrium towards the formation of the imine by trapping water upon its formation during the imination process. The low cost, low toxic and commercially available titanium-based Ti(OEt)4 was found to be a suitable catalyst for the polymerization. After optimizing the reaction conditions, good conversions (>95%) of the monomers were achieved, forming oligomers with molecular weights ranging from 3000 to 8500 g/mol after quenching and removal of the Lewis acid. The low molecular weights obtained can be explained by the dynamic nature of the imine bond that may have hydrolyzed during the quenching step. The authors interestingly demonstrated the pH-responsiveness of the formed products; the lower the pH, the faster the hydrolysis occurred. Notably at pH 1, some polymers could be fully hydrolyzed within a single day, whereas no polymer degradation was noticed after 24h at pH 7. PHUs can be made soluble in water through reaction of the pendant OH-groups with succinic anhydride followed by neutralization with sodium bicarbonate - Scheme 4.51 . The authors introduced carbonate, ester and ether groups in the PHUs and explored their hydrolytic behavior finding that chemical composition of the bis cyclic carbonate affected the hydrolytic behavior under basic conditions pH = 8 – 10,6. Carbonate-containing PHUs hydrolyze faster than ester-containing PHUs, which in turn hydrolyze faster than ethercontaining ones. Hydrolysis rate increased as the pH increased. At pH = 8, it was rather slow (less than 15 % for the carbonate containing PHUs), but it accelerated at higher pHs (complete hydrolysis of the carbonate containing PHUs in only 7 days). This denotes the tunability of the system depending on the monomer and thus on the polymer structure. The authors chain-extended the water soluble carbonate-based PHUs with the help of α,αdiisothiocyanate-p-xylene, forming thio-urea bridges52 and observed that the longer the PHU chain, the better the hydrolytic resistance of the polymer under alkaline conditions. The authors attributed this behavior to the presence of a higher H-bond density that hindered the water influence on the polymer chain. Moreover, the xylene moiety of the chain extender, bringing a higher hydrophobicity, was assumed to play also a role in this reduced water sensitivity. Chapter 1 – Part B 80 Scheme 4: Preparation of water-soluble PHUs via post-functionalization of pendant OH groups – adapted from Matsukizono and Endo51 The same research team demonstrated that functionalizing the pendant OH-groups into quaternary ammonium chloride moieties also gave water-soluble PHU salts.53 The postfunctionalization of the hydroxyl moieties was performed with chloroacetyl chloride prior to reacting with N,N-dimethyl-n-octylamine to yield the corresponding salt - Scheme 5. Some chloroacetyl-derived PHUs exhibited water-solubility depending on the polymer structure. The synthesis however yielded very short oligomers, with molecular weights ranging from 3800 to 6300 g/mol depending on the diamine used. Good yields of functionalization with the amine were obtained (around 80% in every case). Cross-linked polymers were obtained by reacting the functionalized PHUs with tertiary diamines leading to good self-supported films. Scheme 5: Quaternary ammonium chloride PHUs – adapted from Matsukizono and Endo53 Water-based Non Isocyanate Polyurethanes-Polyureas (NIPUUs) 81 3. Hydrogels Hydrogels can be defined as 3D cross-linked hydrophilic networks. Their affinity to water provides them with the ability to swell and retain 10 to 1000 times their dry weight in water.54 Segmented PUs can be used for hydrogel formation because of their particular mechanical properties and capability of interacting with water through the addition of hydrophilic monomers (e.g. poly ethylene glycol – PEG).55,56 To the best of our knowledge, only one example of poly(hydroxyurethane)-based hydrogel has been published.57 The synthesis consisted in having a carbonated polyethylene glycol diglycidylether reacting with various polyamines in bulk. Three diamines were tested: ,-(ethylenedioxy)diethylamine (EDDA), m-xylylenediamine (m-XDA) and 1.8-diaminooctane (ODA) and a triamine, acting as crosslinking agent: tris(2-aminoethyl)amine (TAEA) - Scheme 6. Subsequent swelling in water allowed the absorption of water and the formation of the final hydrogel. The cross-linking degree of the final material (controlled by the amount of triamine introduced) influenced the rheology of the material: a minimum of 0.2 eq. of triamine with respect to the biscyclic carbonate was necessary to avoid free flowing. On the other hand, 0.33 eq. yielded very brittle materials, suggesting a higher crosslinking degree, as confirmed by measurement of the gel content in water (from 67.5 ± 1.2% to 80.7 ± 1.5% when going from 0.2 to 0.33 eq.). Between these two limits, the water uptake of the final material increased as the amount of cross-linking agent decreased (equilibrium water absorption up to 500% were obtained). Moreover, compression tests in the swollen state showed that a higher content in triamine led to higher compression moduli (from 19.1 ± 0.7 to 185.5 ± 36.7 kPa when going from 0.2 to 0.33 eq.), lower strains at break (from 61.0 ± 3.4 to 43.6 ± 5.1% when going from 0.2 to 0.33 eq.) and higher stresses at break (from 43.4 ± 5.4 to 170.0 ±44.7 kPa when going from 0.2 to 0.33 eq.). Those properties were also found to strongly depend on the type of diamine used. For instance, the most hydrophilic EDDA gave the highest equilibrium water absorption (967 ± 9 %) whereas mXDA and ODA gave lower values (505 ± 54% and 214 ± 2% respectively). The difference the last two was attributed to the lower distance between crosslinking points in the case of mXDA, increasing its hydrophilicity. Moreover, the decrease in the equilibrium water absorption (EWA) induced that more stress was needed to compress the hydrogel. This increased the resulting compression moduli (from 37.1 ± 4.3 kPa to 125.3 ± 5.6 kPa for EWA of 967 ± 9% and 214 ± 2%, respectively) and stress at break (from 22.4 ± 8.4 kPA to 830 ± 140 kPa for EWA of 967 ± 9% and 214 ± 2%, respectively). No influence of the introduction of nanoclay (in this case Montmorillonite) on the gel content was observed in the copolymer made of 1eq. of the PEG bis carbonate, 0.2 eq. of the triamine and 0.7 eq. of mXDA, (loading from 1wt% up to 15wt% of clay were studied). It was however demonstrated that it had an effect on the mechanical properties in terms of compression properties. When the nanoclay loading was varied from 2 and 5wt%, the equilibrium water absorption remained around 400%, but the Chapter 1 – Part B 82 compression moduli varied between 15.7 ± 0.2 kPa and 23.9 ± 1.4kPa, the strain at break between 68.0 ± 0.7 and 79.3 ± 1.6% and the stress at break also varied between 60.0 ± 4.0 and 157.2 ± 4.7 kPa. Higher loadings gave hydrogels with lower equilibrium water absorption (down to 56.9 ± 0.7% at 15wt% loading of nanoclay). Scheme 6: Preparation of cross-linked PHUs for the formation of hydrogels – adapted from Detrembleur and coworkers57 4. Water-borne Dispersions 4.1. Acetone-like process Dispersions of polyurethanes are very important products in the coating and adhesive markets due to the relatively easy synthesis and good performance. PUs are usually synthesized through the so-called acetone processScheme 7.15,58. In this process, the PU prepolymers are synthesized in a water miscible low boiling point solvent, commonly acetone. An internal dispersing agent such as dimethylolpropionic acid (DMPA) is usually added into the formulation and allows for dispersion in the water phase upon neutralization (usually performed with the help of trimethylamine). The PU is then chain-extended with a short diol or diamine and after acetone is removed, the PU dispersion is finally obtained. Most of the published examples of isocyanate-free PUs or PUreas dispersions are inspired in the acetone process, namely the copolymerization of three monomers, including an internal dispersing agent is done in a low boiling point solvent. The subsequent neutralization of the formed polymer chains allows the dispersion upon water addition. The removal of the low boiling point solvent leads to the final waterborne dispersion. Water-based Non Isocyanate Polyurethanes-Polyureas (NIPUUs) 83 Scheme 7: Water-borne PUs through the acetone process 4.1.1. NIPUs dispersion by acetone-like transesterification processes The very first example of NIPU water-based dispersion was published in 1996 by Blank et al.,59 who investigated the properties of cross-linked polyurethane dispersions. They used the transurethanization process for the formation of NIPUs from polyester polyols (with an acid number of 1-2) and bis-hydroxypropylcarbamates and a triol, using a transesterification catalyst (dibutyltin oxide). The reaction was carried out under vacuum with a progressive increase in the temperature up to 175°C. The amount of the formed distillate (1,2-propylene glycol) as well as the increase in viscosity helped monitoring the extent of polymerization. Carboxyl functionality was brought by reacting an anhydride onto the OH chain-ends. 35 and 41wt% dispersion were prepared without any co-solvent (which is a difference with the acetone-process), with a neutralization step by means of diisopropanolamine and/or triethylamine. The cross-linking was performed by addition of water dispersible hexa(methoxymethyl)melamine. The dispersions were used in coating applications and paints. Chapter 1 – Part B 84 In 2018, Ma et al. published a series of studies exploring non-isocyanate strategies for the production of waterborne polyurea dispersions for coatings.60,61 Their approach consisted in utilizing a transurethanization-like process in bulk under vacuum. To do so, they copolymerized a bis-alkylcarbamate monomer with two diamines, one of them playing the role of internal dispersing agent (IDA) to form a pre-polymer, that was further dissolved in methnaol. After neutralization, usually with the help of acetic acid, the mixture was slowly added into water. The removal of methanol gave the final dispersion - Scheme 8. The authors demonstrated that during the pre-polymerization step, the nature of the alkylleaving group of the bis-carbamate as well as the process conditions (such as high vacuum)were found to be of outmost importance for the reaction to give polyureas with high enough molecular weights.60,61 Scheme 8: Preparation of water-borne non-isocyanate polyureas – adapted from Ma et al60,61 The successful implementation of this process strongly depends on the ability of the transurethanization reaction to proceed without too many side-reactions. The nucleophilic attack of the diamine onto the bis-carbamate to yield the corresponding urea moiety is in competition with the N-alkylation reaction that can proceed through a decarboxylation mechanism – Scheme 9. This reaction is undesirable since it would lead to a deviation from the stoichiometric ratio, and hence to lower molecular weights. Water-based Non Isocyanate Polyurethanes-Polyureas (NIPUUs) 85 Scheme 9: N-alkylation reaction in competition with the transurethanization in the reaction between a biscarbamate and a diamine – adapted from Ma et al.60 The authors demonstrated that the N-alkylation reaction could be mitigated by changing the alkyl moiety located on the bis-carbamate compound60,61. Bulkier alkyl-groups reduced the rate of the decarboxylation process, thus favoring the polyurea formation. Indeed, the tert-butoxyl moiety was more selective towards urea formation than the ethyl groups, which itself was more selective than methyl groups. The alkyl moiety on the bis-carbamate also affected kinetics and it was found that the urea formation was faster in the following order: tert-butoxyl > methyl > ethyl. In the case of methyland ethyl-group, the bulkier ethyl-group sterically hindered the nucleophilic addition of the diamine onto the biscarbamate moiety. The case of tert-butoxy group was more intriguing, since faster kinetics was observed despite the bulkiness. The authors explained this fast kinetics by the mechanism of the reaction proceeding via the in situ formation of an isocyanate moiety. The type of diamine used, and the efficiency of the removal of the generated alcohol also played a very important role in the mitigation of N-alkylation. Regarding the diamines, sterically less hindered primary diamines had faster rates of N-alkylation than the bulkier ones (secondary diamines or primary amines attached to a tertiary carbon). Removal of the alcohol favored the transurethanization reaction and the generation of higher molecular weight polyureas. In general, relatively high molecular weights (16 to 65 kDa) were obtained.60,61 In order to disperse the formed polyurea chains, internal dispersing agents (IDA) were used. Their subsequent neutralization allowed for the polymer chains to form nanoparticles in water. The higher molar percentages (varied from 10 to 30 mol.% in diamine) of IDA were used.60,61 The higher surface-charge density on the particles led to smaller particles (for example, in the case of a series of copolymers composed of isophorone dimethylcarbamate, 4,7,10-trioxa-1,13-tridecanediamine and ,-diamino-Nmethydipropylamine – used as IDA – the particle diameters varied from 280 nm for 10 mol% IDA in diamine to 44 nm for 30mol% IDA in diamine).60 The coatings cast from these dispersions exhibited pencil hardness ranging between HB and 2B (even B to 6B when changing the diamine) and good resistance to acetone. The molecular weights of the polymer influenced the entanglement densities of the polymer chains and it was observed that polyurea coatings with molecular weights lower tham 30 kDa exhibited poorer impact resistance than coatings with higher molecular weights. Moreover, longer monomers that Chapter 1 – Part B 86 increase the distance between urea moieties tended to decrease the H-bond density resulting in softer coatings. In 2018, the same research team demonstrated that ethylenediaminetetraacetic dianhydride (EDTAD) could be successfully incorporated as an IDA into the NIPUrea formulation,62 Forming two pendent carboxylic acid moieties upon opening of the anhydride opening – Scheme 10. Scheme 10: Water-borne NIPUreas using EDTAD as internal dispersing agent – adapted from Ma et al62 The very high density of H-bonds in this system induced gelation, which was also favored by the ionic interactions provided by the zwitterionic form of the amic acid – Scheme 11. The use of an asymmetric isophorone-based bis-carbamate disrupted the establishment of H-bonds between the urea moieties and reduced the extent for gelation.62 Scheme 11: Zwitterionic form of the amic acid after aminolysis of EDTAD – adapted from Ma et al62 Water-based Non Isocyanate Polyurethanes-Polyureas (NIPUUs) 87 The advantage of such an internal dispersing agent is the very fine tunability of the neutralization step. The concomitant ionization of the amic acid in its zwitterionic form as well as the neutralization by means of adding triethylamine (NEt3, TEA) allows for a fine tuning of the particle size of the dispersion (particles diameter ranging from 900 to 8 nm were obtained depending on the conditions). However, the formation of the zwitterionic moiety alone was not enough for stabilizing the dispersion since the polyurea precipitated if no NEt3 was added prior to dispersion. When increasing the TEA/COOH ratio, the particle size dramatically decreased and the viscosity of the latex increased, which above a certain value can be detrimental for coating applications. As an example, the particle size as measured by dynamic light scattering (DLS) decreased from 900 nm to 14 nm when the ratio was varied from 0.1 to 1.0. In order to circumvent this effect, the authors tried to reduce the concentration of ionic groups in the final polyurea while targeting 100% neutralization of the pendent acidic moieties. This was done by increasing the diaminoprepolymer/EDTAD ratio and neutralizing the carboxyl groups with a stoichiometric amount of trimethylamine. The authors also reduced the ionic content in the final polymer by increasing the molecular weight of the diamino prepolymer. Prepolymer molecular weights ranging from 950 Da to 4750 Da were prepared varying the diamine/carbamate ratio from 2 to 1. Using these prepolymers, the particle size increased from 8 nm (Mnprepolymer = 950 Da) to 61 nm (Mnprepolymer = 4750 Da). Most of the polymers had a relatively high Tg and therefore no film could be cast at room temperature. Coatings could be formed by casting at 50°C for 6 h followed by a thermal treatment at 110-150°C for 24 h. Moreover, these polymers did not form coatings with interesting properties since they were brittle and certainly did not get chain extended enough to reach the minimum entanglement molecular weight, which is needed to obtain polymers with interesting mechanical properties. The coatings were prepared at 50°C on aluminum panels. The curing temperature was found to be very important since higher temperatures led to coating with higher hardness, better adhesion properties as well as better solvent resistance. This was attributed to a non cyclic imidization crosslinking mechanism – namely the reaction between pendent COOH moieties with amides from the polyureas. This result was confirmed by an increase in the gel fraction of the obtained materials. 4.1.2. NIPUs dispersion by acetone-like aminolysis processes Only two examples of poly(hydroxy urethane) dispersions have been reported. The first example dates back to 2008 with a patent from Rhodia.63 The patent discloses the PHU synthesis and the formation of aqueous dispersions to be used as coatings and adhesives. Most of the examples are in reality hydro-organic solutions and the obtained latexes are not organic solvent-free. In these cases, PHUs were synthesized in an organic solvent such as ethanol or Highlink W (Clariant™). Dihydroxyurethane adducts of isophorone diamine and Chapter 1 – Part B 94 6. Conclusions This work reviews the water-based non-isocyanate polyurethane-ureas (NIPUUs), a new class of materials that are a greener alternative to the traditional isocyanate-based polyurethane-ureas. NIPUUs can be formed by either the transurethanization process, yielding polyurethane/ureas, and the aminolysis of biscyclic carbonates, yielding poly(hydroxyurethane)s (PHUs). Neither of the two approaches is free from problems. Nalkylation side-reaction can occur during the transurethanization process. This side reaction can be mitigated by changing the alkyl moiety located on the bis-carbamate compound. Bulky groups such as tert-butoxyl-, phenyl-, nitrophenyland pentafluorophenyl-moieties reduce the side reaction, but the purification of the aromatic moieties remains challenging, and tert-butoxyl-groups work through the formation of an in situ isocyanate moiety in their mechanism, which can seem questionable if a full isocyanatefree process is desired. On the other hand, the use of aminolysis in aqueous media is challenging because cyclic carbonates are prone to suffer hydrolysis. Both water-soluble NIPUUs and waterborne NIPUU dispersions can be prepared by varying the hydrophilicity of the monomers. In principle, both aminolysis and transurethanization can be used to directly synthesize water-soluble NIPUUs in water. However, the use of aminolysis is precluded by the propensity of the cyclic carbonates to suffer hydrolysis. Transurethanization using functional bis-carbonates allowed obtaining water-soluble NIPUs. A likely easier to apply approach is the modification of NIPUs synthesized in organic solvents. Imines, neutralized carboxyl groups and quaternary ammonium chloride moieties have been used to render the preformed NIPUs soluble in water. Some widely different methods have been used to synthesize waterborne NIPUU dispersions. A method that looks promising is the acetone-like process. In this process, NIPUUs containing internal dispersing moieties (e.g. carboxyl or zwitterionic) are synthesized in a low boiling point organic solvent such as acetone using either transurethanization or aminolysis. The polymer solution is then dispersed in water and the solvent removed by evaporation. NIPUU dispersions can also be synthesized by interfacial transurethanization with the carbamate in the organic phase and the diamine in the aqueous phase. Miniemulsion polymerization has been used to synthesize NIPU dispersions by the aminolysis process. Poly(hydroxyurethane)s synthesized by aminolysis have been used to prepare NIPU dispersions by nanoprecipitation. Water-based Non Isocyanate Polyurethanes-Polyureas (NIPUUs) 95 As in the case of classical PUs, it is expected that hybrids composed by NIPUs and other polymers yield materials with synergistic properties. Therefore, NIPU-acrylics and NIPUepoxy hybrids have been synthesized showing synergistic improvement of the performance. Substantial advances in the development of water-based NIPUs have been done in the last years. These studies show that the structure of the monomers plays a critical role in both the feasibility of the synthetic process and the type of polymer obtained. Further developments will require easier methods for the synthesis and purification of the monomers, to understand the effect of the polymerization method on the polymer microstructure and that of the microstructure on the performance. It is hoped that these developments will bring water-based NIPUUs closer to industrial implementation. 7. References (1) Bayer, O. Das Di-Isocyanat-Polyadditionsverfahren (Polyurethane). Angew. Chemie 1947, 59 (9), 257–272. (2) PlasticsEurope AISBL. Plastics-the Facts 2018 An analysis of European plastics production, demand and waste data https://www.plasticseurope.org/en/resources/market-data (accessed Jan 17, 2019). (3) Engels, H. W.; Pirkl, H. G.; Albers, R.; Albach, R. 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Shortened forms BA: Butyl Acrylate BADGE: Bisphenol-A Diglycidyl Ether CMR: Carcinogenic, mutagenic, reprotoxic CO2: Carbon Dioxide DCM: Dichloromethane DLS : Dynamic Light Scattering DMF: Dimethylformamide DMPA: Simethylolpropionic Acid DMSO: Dimethylsulfoxide DPA: Diphenolic Acid DSC : Differential Scanning Calorimetry EDDA : ,-(ethylenedioxy)diethyl-amine EDTAD: Ethylenediaminetetraacetic Dianhydride HMDA: Hexamethylene Diamine IDA: Internal Dispersing Agent IPDA: Isophorone Diamine MFFT: Minimum Film Formation Temperature MMA: Methyl Methacrylate m-XDA: m-xylylenediamine NaHCO3: Sodium Bicarbonate NIPU: Non Isocyanate Polyurethane NMP: N-Methyl pyrrolidone ODA: 1.8-diaminooctane PEG: Poly(ethylene) glycol PGMAC: Propylene Glycol Methyl Acetate PHU: Poly(hydroxyurethane) PU: Polyurethane PUI: Poly(urethane–co–imine) SDS: Sodium Dodecyl Sulfate SEM: Scanning Electron Microscopy TAEA: Tris(2-aminoethyl)amine TEA: triethylamine TEM: Transmission Electron Microscopy Ti(OEt)4: Titanium Ethoxide Tg: Glass Transition Temperature TMDA: Tetramethylene diamine UMAs: Urethane methacrylates PART C OBJECTIVES & OUTLINE Chapter 1 – Part C 102 From the state-of-the-art, it appears that Hybrid-Non Isocyanate Polyurethanes (HNIPUs) are interesting new materials with properties arising from a synergistic combination of those of the constitutive units. Moreover, in only a few examples the potential of such hybrid materials in water-borne systems has been explored.1–3 Therefore, the purpose of this thesis was to synthesize novel water-borne hybrid-NIPU materials (H-NIPUs) by combining bio-based isocyanate-free poly(hydroxy urethane)s (PHUs) pre-polymers with (meth)acrylates. In order to fulfill this goal, several challenges should be overcome such as the synthesis of specific monomers (in this case bis-cyclic carbonates), the bulk polymerization of these monomers with diamines to form the PHUs, the selection of a suitable acrylic phase to dissolve these PHUs and finally the polymerization of the acrylic phase in a mini-emulsion process. As the characteristics and properties of the hybrids are expected to depend on the interaction between the PHU and the acrylic polymer, both grafted and non-grafted hybrids were synthesized and the properties of the resulting coatings investigated. The rest of this thesis will be divided in four chapters. Chapter 2 deals with the bulk synthesis of bio-based poly(hydroxy urethane)s - PHUs. The design of ester-activated bis-cyclic carbonates of different aliphatic chain length is described, as well as their polymerization behavior with various fatty acid-based diamines. The relationship between the structure of the PHU and the thermal and viscoelastic properties is investigated. Chapter 3 is dedicated to the design of water-borne non-cross-linked PHU-Poly(butyl methacrylic) H-NIPUs using mini-emulsion. In this chapter, a 2-step process was implemented. Fatty acid based-PHUs were firstly synthesized in bulk and then dissolved in a mixture of butyl methacrylate and stearyl acrylate (BMA + SA). The resulting mixture was then emulsified by sonication and the acrylic phase polymerized. Different latexes, having compositions ranging from 0 to 30 wt.% PHU, were obtained, and the polymerization behavior of the acrylic phase was studied, in terms of kinetics and particle size. The performance of the films cast from the hybrid waterborne dispersions was studied. In Chapter 4, waterborne grafted PHU-poly(meth)acrylate hybrid dispersions were synthesized and the effect of grafting on the particle and film morphologies as well as on the mechanical properties of the films was investigated. Chapter 5 provides the general conclusions and perspectives to this work. Objectives & Outline 103 References (1) Ma, Z.; Li, C.; Fan, H.; Wan, J.; Luo, Y.; Li, B. G. Polyhydroxyurethanes (PHUs) Derived from Diphenolic Acid and Carbon Dioxide and Their Application in Solventand WaterBorne PHU Coatings. Ind. Eng. Chem. Res. 2017, 56 (47), 14089–14100. (2) Meng, L.; Wang, X.; Ocepek, M.; Soucek, M. D. A New Class of Non-Isocyanate Urethane Methacrylates for the Urethane Latexes. Polymer (Guildf). 2017, 109, 146–159. (3) Meng, L.; Soucek, M. D.; Li, Z.; Miyoshi, T. Investigation of a Non-Isocyanate Urethane Functional Monomer in Latexes by Emulsion Polymerization. Polymer (Guildf). 2017, 119, 83–97. Chapter 2 110 differential refractive index detector (dRI) from Wyatt technology. Polymers were separated on two KD803 Shodex gel columns and one KD804 Shodex gel columns (300 x 8 mm) (exclusion limits from 1000 Da to 700 000 Da) at a flowrate of 0.8 mL/min. Column temperature was held at 50°C. Easivial kit of Polystyrene from Agilent was used as the standard (Mn from 162 to 364 000 Da). Differential Scanning Calorimetry (DSC) thermograms were measured using a DSC Q100-RSC or a DSC Q100-LN2 apparatus from TA Instruments. In the DSC Q100-RSC, the measurements were performed over a temperature range from -80°C to 160°C, with a heating cooling rate of 10°C.min-1. The analyses were carried out in a nitrogen atmosphere in aluminum pans. In the DSC Q-100-LN2, the measurements were performed over temperature ranging from -150°C to 160°C, with a heating cooling rate of 10°C.min-1. The analyses were carried out in a helium atmosphere with aluminum pans. The glass transition temperatures (Tgs) were calculated from the second heating ramp. Thermogravimetric Analyses (TGA) were performed on a TA-Q500 apparatus from TA Instruments with a heating rate of 10°C.min-1 under a nitrogen atmosphere from room temperature until 700°C. The rheology experiments were carried out in a stress-controlled Anton Paar Physica MCR101 rheometer. Small-amplitude oscillatory experiments were carried out using 25 mm parallel plate geometry. All the experiments were conducted in linear viscoelastic conditions for the studied temperature range (strain = 0.5% and frequency 1 Hz). Regarding the theoretical mechanistic study, all geometry optimizations were carried out in gas phase within density functional theory (DFT), combined with the 6-31+G(d,p) basis set. Harmonic vibrational frequencies were obtained by analytical differentiation of gradients, in order to determine whether the structures found are minima or transition states. The frequencies were then used to evaluate the zero-point vibrational energy (ZPVE) and the thermal (T = 298 K) vibrational corrections to the enthalpy (H) in the harmonic oscillator approximation. Single point calculations using the 6-311++G(2df,2p) basis set were performed on the optimized structures in order to refine the electronic energy, and the previously calculated corrections to the enthalpy were used to calculate the H of each speciesAll DFT calculations were carried out using the Gaussian 16 package. Bulk Synthesis of bio-based Poly(Hydroxy Urethane)s – PHUs 111 2.2. Standard Procedure for polymerization Poly(hydroxy)urethanes (PHUs) were synthesized using bisCC-C4 and bisCC-C10 with 10DA and P1075 as comonomers (Scheme 2). Stoichiometric ratios for the reactive moieties were targeted to maximize the molecular weights according to the Carother’s theory. The reactions were performed in bulk at 90°C for 24h in a Schlenk tube using a helical shaped mechanical stirrer specifically designed to fit in the Schlenk vessel. No catalyst was added for the polymerization reactions. No purification of the PHUs was performed after reaction. Conversions were determined by 1H-NMR spectroscopy after 24h reaction time. Scheme 2: PHU synthesis through copolymerization of bisCC-C4 and bisCC-C10 with 10DA and P1075 2.3. Bis-cyclic carbonate synthesis bisCC-C10 synthesis. In a three-neck round bottom flask, 2.2 eq. (30 g, 254 mmol) of glycerol carbonate and 2.2 eq. (25.707 g, 254 mmol) of trimethylamine were added to 100 mL of dichloromethane (DCM). This mixture was cooled down with the help of an ice bath and 1 eq. (27.615 g, 115.5 mol) of sebacoyl chloride was added dropwise. The reaction mixture was left under stirring for 24 h at room temperature. After reaction, the product was purified by means of the following liquid-liquid extraction steps: 5 times with 200 mL of an acid solution (5wt.% HCl), followed by 3 times with a basic treatment (stirring with basic alumina during 1h, followed by filtration of the liquid DCM phase), and finally 1 washing step with brine. The isolated organic phase was then dried with MgSO4, filtered over a sintered filter and the dichloromethane was removed under reduced pressure. The obtained white powder was then analyzed by 1H-NMR. The white powder was dried in a vacuum oven at 40°C overnight to remove any traces of remaining solvent. Yield: 50 % 1H-NMR: δ H (400 MHz, DMSO-d6) 5.10 – 4.97 (2 H, m), 4.57 (2 H, t), 4.43 – 4.17 (6 H, m), 2.33 (4 H, t), 1.51 (4 H, q), 1.25 (8 H, d). bisCC-C4 synthesis. In a three-neck round bottom flask, 1 eq. (2.032 g, 20.33 mmol) of succinic anhydride and 0.3 eq. (0.745 g, 6.10 mmol) of 4-dimethylaminopyridine (DMAP) were added in 30 mL of acetonitrile (ACN). This mixture was heated up to 70°C with the help of an oil bath until Chapter 2 112 solubilization of the reagents and 2.5 eq. (6.000 g, 50.81 mmol) of glycerol carbonate were added dropwise. The mixture was left to react under magnetic stirring during 6h and the conversion of the succinic anhydride into the mono-carbonate derivative was checked by 1H-NMR analysis. The reaction mixture was then cooled down to room temperature and then 1.5 eq. (6.291 g, 30.49 mmol) of N,N'-Dicyclohexylcarbodiimide (DCC) was added. The mixture was left under magnetic stirring overnight (16h) and the formation of a white precipitate of dicyclohexylurea (DCU) was noticed. After checking that full conversion was achieved by 1H-NMR, the reaction mixture was filtered over a sintered filter and the ACN was removed under reduced pressure. The formation of a white powder was noticed. This powder was then washed with cold DCM (50 mL) in a sintered filter to remove the excess of glycerol carbonate, DCC and DMAP that are soluble in it. The purity of the product was checked by 1H-NMR. The final product was then dried in a vacuum oven overnight to remove any trace of remaining solvent. Yield: 40%. 1H-NMR: δ H (400 MHz, DMSO-d6) 5.03 (2 H, m), 4.57 (2 H, t), 4.37 – 4.20 (6 H, m), 2.63 (4 H, d, J 1.0). 3. Results and Discussion 3.1. Activated bio-sourced bis-cyclic carbonates (bisCCs) The synthesis of the bis cyclic carbonate from Sebacoyl Chloride (bisCC-C10) was adapted from Carré et al. and relies on the esterification reaction between the fatty diacidbased diacyl chloride and glycerol carbonate (Scheme 3).54 Scheme 3: Synthesis of the bis cyclic carbonate from sebacoyl chloride (bisCC-C10). After purification, the product could be obtained as a white powder with a yield of 50%. The formation of the expected product was attested by 1H-NMR spectroscopy (Figure 1). Bulk Synthesis of bio-based Poly(Hydroxy Urethane)s – PHUs 113 Figure 1: Stacked 1H-NMR Spectra of Sebacoyl Chloride in CDCl3 (top) and bisCC-C10 in CDCl3 (middle) and in DMSO-d6 (bottom) Another bio-sourced bis-cyclic carbonate monomer of shorter chain length was also synthesized. The synthetic pathway relies on the ring opening of succinic anhydride by an excess of glycerol carbonate (Scheme 4). The reaction proceeded in a 1pot-2step process in acetonitrile. The first step consisted in the formation of the mono-carbonate derivative of succinic acid after 6h reaction as revealed by 1H-NMR spectroscopy (Figure 2). The reaction was catalyzed by 4-dimethylaminopyridine (DMAP). In the second step, the mild Steglich esterification was employed, namely the addition of N,N'- dicyclohexylcarbodiimide (DCC) in combination with the already present DMAP and the unreacted glycerol carbonate allowed the formation of the final bisCC-C4. Acetonitrile (ACN) was found to be a suitable solvent to solubilize both the anhydride and the glycerol carbonate. It also favors the precipitation of the dicyclohexylurea by-product (DCU) that formed upon reaction of the DCC coupling agent, hence shifting the equilibrium of the esterification reaction towards the complete formation of the bis-cyclic carbonate compound. DMAP was also found to be a suitable catalyst as it catalyzes both reaction steps. The purification process consisted in a filtration step to remove the precipitated DCU by-product, then the evaporation of ACN, followed by a washing step with cold dichloromethane to remove the remaining unreacted species without using any chromatographic separation method. The final yield was 40%, yielding 2,57g of product. The 1H-NMR monitoring of the reaction (Figure 2) and the reaction was scaled up to the formation of 16g of bisCC-C4 with a good purity as exemplified by 1H-NMR spectroscopy (Figure 2). 1 2 3 1 23 3 5 64,6 1 2 3 DMSO * * 1 2 4 53 3 6 bisCC-C10 5 6 4,6 1 2 3 CDCl3 1 2 4 53 3 6 bisCC-C10 Chapter 2 114 Scheme 4: Synthesis of the bis-cyclic carbonate from succinic anhydride (bisCC-C4). Figure 2: Stacked 1H-NMR Spectra of Succinic Anhydride, the reaction crude before the addition DCC and of bisCC-C4 (from top to bottom) in DMSO-d6. Unfortunately, when trying to scale the synthesis up for the formation of about 27g of bisCC-C4 (and have enough starting material to perform reactions in bulk conditions with mechanical stirring), it was not possible to obtain bisCC-C4 that was completely pure. As can be seen in Figure 3, traces of glycerol carbonate (around 5 %) were still observed despite several washing steps with cold dichloromethane. Moreover, a low yield of 51% was obtained. Even if such a purity was not satisfactory, it was desired to know the range of properties that could be obtained when decreasing the aliphatic chain length of the bisCC monomer. bisCC-C4 and bisCC-C10 were thus copolymerized with an aliphatic and a branched fatty acid-based diamines (namely 1,10-diaminodecane – 10DA, and the commercially available PriamineTM 1075 – P1075). bisCC-C4 1 1 1 2 3 4 5 1 2 3 41 2,4 4 3 4 ’ ’ ’ 4’5 ’ ,,’ 3’ 2 1 H2ODMSO Bulk Synthesis of bio-based Poly(Hydroxy Urethane)s – PHUs 115 Figure 3: Stacked 1H-NMR Spectra of Glycerol Carbonate and bisCC-C4 after scale-up (from top to bottom) in DMSO-d6. 3.2. Copolymerization of bisCC-C4 and bisCC-C10 with mixtures of diamines Achieving the bulk polymerization of PHUs affording sufficiently high molecular weight polymers is of high interest. To do so, it is needed to both overcome the high viscosity of the formed PHUs upon synthesis as well as avoiding side-reactions.44 On the one hand, high viscosity can be imparted to the formation of hydrogen bonds between the PHU chains.17 A helical shaped mechanical stirrer specifically designed to fit in the used Schlenk vessel was utilized to provide constant agitation throughout the entire polymerization process. On the other hand, it is known that ester-activated bisCCs suffer from side-reactions.8,33 The formation of urea and amide by-products has been reported and also explains the low molecular weights generally obtained. The synthesized ester-activated 5-membered bis-cyclic carbonate compounds were thus polymerized to form poly(hydroxy urethane)s (PHUs). To do so, bisCC-C4 and bisCCC10 were copolymerized with various ratios of the aliphatic (solid) 1,10-diaminodecane (10DA) and the commercially branched (liquid) Priamine® 1075 (P1075). The monomers reacted during 24h at 90°C in bulk under mechanical stirring - Scheme 2. A temperature of 90°C was chosen since it was high enough to promote both the melting of the diamine and of the formed PHUs. Table 1 summarizes the reactions carried out and the characteristics of the polymers obtained. The purpose of using P1075 in the formulation was to see whether any plasticization of the PHU product would be beneficial for the implementation of the bulk process. 1 3 ’ ’ ’ ’ 4 ’ ,,’ 2’ DMSO 3’4’ ’ 2’ 6’ 6’ ’ 6’ ’ * * bisCC-C4 1 2 3 4 6’ * Chapter 2 116 Table 1: Chemical composition and characterization of the PHUs obtained by copolymerization of 10DA, P1075 together with bisCC-C4 or bisCC-C10, in bulk, at 90°C during 24h Run Co-monomers [%] Conv.a [%] Mn b [g.mol-1] Đ b Apparent DP c bisCC10DA P1075 01 C4 100% 87 16 700 1.7 34 02 C4 75% 25% 83 12 500 1.8 21 03 C4 50% 50% 86 11 900 1.5 18 04 C4 25% 75% 79 12 000 1.5 16 05 C4 100% 75 10 400 1.4 12 06 C10 100% 93 33 900 2.2 59 07 C10 75% 25% 88 24 800 2.9 37 08 C10 50% 50% 91 22 700 3.0 30 09 C10 25% 75% 89 19 900 2.9 23 10 C10 100% 70 20 600 2.3 11 a Conversions of reactive functions were calculated by 1H NMR. b Mn values were obtained by SEC in DMF with LiBr salts, PS calibration c The apparent Degree of Polymerization (DP) was calculated from the Mn values obtained by SEC Figure 4: 1H-NMR spectra of PHU 01 (bottom) and PHU 06 (top) In the reactions (Table 1), the formation of the urethane moiety was checked by 1HNMR spectroscopy by following the disappearance of the signal corresponding to the quaternary carbon of the cyclic carbonate moiety (in the range of 5.0 ppm). The characteristic signal of the protons located in alpha-position of the urethane moieties (CH2-NHC(O)O-) could be identified in the range 2.8-3.2 ppm (Figure 4 – Figure S1 to S10). Infrared spectroscopy (FTIR, in Figure S15 and S16) also revealed the disappearance of ’ A ’ ’ 4 ’ ’ ’ ’’ ’’ ’’ 4 5 * * ’’ ’’ ’’ A B ’ ’’ ’ ’’ U U U U NH amide NH amide NH urea NH urea ’’ ’’ ’ ’ ’ ’ ’’ ’’ ’’ ’ A A4 4 + DMSO DMSO B 5, B 5, B ’’ ’’ ’’ ’ ** ** Bulk Synthesis of bio-based Poly(Hydroxy Urethane)s – PHUs 117 the C=O stretching band of the cyclic carbonate moiety at 1800 cm-1 and the appearance of the C=O stretching band attributed to the urethane moiety at 1700 cm-1 as well as OH moieties (band at 3330 cm-1). The C=O stretching band also exhibited the presence of a shoulder towards lower wavenumbers, that could be explained by stretching of the C=O function of the urea side-product. The reaction extents gauged by 1H-NMR analysis showed that bisCC-C4 and bisCC-C10 did not exhibit the same behavior upon polymerization. The reaction extents usually were higher when bisCC-C10 was used as comonomer (approaching 90%), which can be explained by the higher purity of the starting bisCC-C10. As a logical outcome according to the Carother’s theory, the molecular weights and thus the apparent degrees of polymerization reached higher values in the case of bisCC-C10. As a general trend, the molecular weights of the PHUs obtained from bis-CC10 were found to be twice as much greater than those from bisCC-C4 (Table 1). This can certainly be explained by the presence of some glycerol carbonate left in the batch of bisCC-C4. Moreover, it could also be noticed that the higher the content in 10DA, the higher the reaction extents, and the higher the resulting apparent degrees of polymerization. Indeed, they were close to 90% in the case of 10DA and between close to 70% in the case of P1075. The lower conversions with P1075 can be explained due to a deviation from the stoichiometric ratio explained by the lower purity of the P1075. A positive outcome concerns Run 06. Previous works showed that same polymer prepared in DMF exhibited a Mn of 13700 g.mol-1 (Đ = 3.7) for a reaction extent of 93.5% in 7 days at 70°C.33 In comparison, we managed to reach a significantly higher molecular weight for a similar reaction extent in only 24h. This could suggest that a lower amount of side reactions occurred. A potential explanation of this feature could be the higher temperature, as well as the lower reaction time utilized in our process. The higher temperature would increase the reaction kinetics and the lower reaction time would leave less time for the side reactions to occur. 1H-NMR spectroscopy was used to shed some light on the side reactions by analyzing the chemical microstructure of the formed PHUs (Figure 4). It is known that the amine function can react with the forming urethane and with the ester groups to produce urea and amide moieties, respectively - Scheme 5.8,33 The quantification of those by-products is important to get an idea on the final polymer microstructure and also to explain the rather low molecular weights obtained. As exemplified by previous works,33 the urethane : urea : amide ratios can be quantified by analyzing the labile-proton zone (from 6.5 ppm to 8.0 ppm) provided the analyses are performed in DMSO-d6. This was done for both series of PHUs as shown in Figure 5. Scheme 5: Suggested mechanism of the reaction between any NH2-terminated compound and the urethane or the ester moieties contained in the backbone of the growing PHUs to yield ureaand amide-containing side-products respectively. The chemical microstructure of the PHUs showed differences depending on the utilized bisCC comonomer. Higher ratios of urethane moiety were obtained (more than 80%) when high reaction extents (approaching 90%) were achieved, especially when high ratios of 10DA are utilized (Figure 5). This value is in accordance with what is observed in the literature. The formation of up to 10% urea was not a surprise since avoiding this reaction is known to be very improbable.33 However, the amount of amide formed was in the range of 5 to 20%, which can be considered as a high extent of amidification as opposed to DMF-based processes.33 This might be due to the use of bulk conditions, in which the reactive chains are in a much intimate contact than in solvents. Moreover, the use of ester-containing bisCCs increases the amount of formed H-bonds in the reactive mixture, yielding highly viscous mixtures. All of these parameters favor the neighboring of the reactive functions and can explain why a high extent of amidification was observed. When analyzing again the specific case of Run 06, the urea : amide : urethane ratio was of 10.1 : 5.9 : 84 in the DMF process33 whereas the ratio surprisingly was 4.5 : 0.5 : 95 with the bulk process. This supports the previous statement that the extent of side-reactions was diminished, hence increasing the resulting molecular weights. A potential explanation would be that, because of the higher purity of the monomers (bisCC-C10 and the aliphatic 10DA), the amount of added monomers was closer to the stoichiometric ratio). When high amounts of P1075 were used, the lower purity of P1075 would increase the deviation to this stoichiometric ratio. 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Crosslinkable Polyurethane Bearing a Methacrylate Structure in the Side Chain. J. Polym. Sci. Part A Polym. Chem. 2007, 45 (15), 3400– 3407. (65) Ochiai, B.; Satoh, Y.; Endo, T. Nucleophilic Polyaddition in Water Based on ChemoSelective Reaction of Cyclic Carbonate with Amine. Green Chem. 2005, 7 (11), 765– 767. 6. Shortened forms ACN: Acetonitrile bisCC-C4: bis cyclic carbonate from succinic anhydride bisCC-C10: bis cyclic carbonate from sebacic acid Ɖ: Polydispersity DCC: N,N'-Dicyclohexylcarbodiimide DCM: Dichloromethane DCU: Dicyclohexylurea DMAP: 4-dimethylaminopyridine DMF: Dimethylformamide DMSO-d6: deuterated dimethylsulfoxide Mn: Molecular weight (in number) Mw: Molecular weight (in weight) NIPU: Non Isocyanate Polyurethane PHU: Poly(hydroxy)urethanes P1075: PriamineTM 1075 Tg: Glass Transition Temperature 10DA: Decane 1,10-diamine DSC: Differential Scanning Calorimetry FTIR: Fourier Transformed Infra-Red-Attenuated Total Reflection NMR: Nuclear Magnetic Resonance SEC: Size Exclusion Chromatography TGA: Thermogravimetric Analyses Chapter 2 130 7. Supporting Information 7.1. NMR analyses Run 01 Figure S1: 1H-NMR spectra of Run 01 in DMSO-d6 Run 02 Figure S2: 1H-NMR spectra of Run 02 in DMSO-d6 Bulk Synthesis of bio-based Poly(Hydroxy Urethane)s – PHUs 131 Run 03 Figure S3: 1H-NMR spectra of Run 03 in DMSO-d6 Run 04 Figure S4: 1H-NMR spectra of Run 04 in DMSO-d6 Chapter 2 132 Run 05 Figure S5: 1H-NMR spectra of Run 05 in DMSO-d6 Run 06 Figure S6: 1H-NMR spectra of Run 06 in DMSO-d6 Bulk Synthesis of bio-based Poly(Hydroxy Urethane)s – PHUs 133 Run 07 Figure S7: 1H-NMR spectra of Run 07 in DMSO-d6 Run 08 Figure S8: 1H-NMR spectra of Run 08 in DMSO-d6 Chapter 2 134 Run 09 Figure S9: 1H-NMR spectra of Run 09 in DMSO-d6 Run 10 Figure S10: 1H-NMR spectra of Run 10 in DMSO-d6 Bulk Synthesis of bio-based Poly(Hydroxy Urethane)s – PHUs 135 Stacked 1H-NMR spectra Fixed bisCC-C4 Figure S11: Stacked 1H-NMR spectra of Run 01, Run 02, Run 03, Run 04 and Run 05 (from bottom to top) in DMSO-d6 Fixed bisCC-C10 Figure S12: Stacked 1H-NMR spectra of Run 06, Run 07, Run 08, Run 09 and Run 10 (from bottom to top) in DMSO-d6 Chapter 2 142 Figure S23: DSC trace of Run 07 (Exo up) Figure S24: DSC trace of Run 08 (Exo up) Figure S25: DSC trace of Run 09 (Exo up) Figure S26: DSC trace of Run 10 (Exo up) Overlay: 1st heating ramp a) -100 -50 0 50 100 150 200 -10 -5 0 5 10 15 20 Heat Flow (W/g) - Exo Up Temperature - 1st heating ramp (°C) 0% 10DA 25% 10DA 50% 10DA 75% 10DA 100% 10DA b) -100 -50 0 50 100 150 -5 0 5 10 15 20 Heat Flow (W/g) - Exo Up Temperature - 1st heating ramp (°C) 0% 10DA 25% 10DA 50% 10DA 75% 10DA 100% 10DA Figure S27: DSC traces of the obtained PHUs by copolymerization of 10DA, P1075 together with a) bisCCC4 or b) bisCC-C10 (1st heating ramp - 10°C/min) 50°C 37°C 32J/g -12°C(I) -1.0 -0.5 0.0 0.5 1.0 Heat Flow (W/g) -100 -50 0 50 100 150 200 250 Temperature (°C) Size: 17.2800 mg Method: BB - Hybrids DSC File: E:\Analyses\DSC\BB318-DSC01.001 Operator: BB Run Date: 04-Jun-2018 12:58 Instrument: DSC Q100 V9.9 Build 303 Exo Up Universal V4.5A TA Instruments 45°C 39°C 15J/g -12°C(I) -1.0 -0.5 0.0 0.5 1.0 Heat Flow (W/g) -100 -50 0 50 100 150 200 Temperature (°C) Sample: BB319-DSC03 (2nd sample) Size: 8.1000 mg Method: BB DSC File: E:\Analyses\DSC\BB319-DSC03.001 Operator: BB Run Date: 11-Jun-2018 15:43 Instrument: DSC Q100 V9.9 Build 303 Exo Up Universal V4.5A TA Instruments 45°C 42°C 1J/g -17°C(I) -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 Heat Flow (W/g) -100 -50 0 50 100 150 200 Temperature (°C) Sample: BB320-DSC01 Size: 13.0200 mg Method: BB DSC File: E:\Analyses\DSC\BB320-DSC01.002 Operator: BB Run Date: 11-Jun-2018 17:00 Instrument: DSC Q100 V9.9 Build 303 Exo Up Universal V4.5A TA Instruments -17°C(I) -0.5 0.0 0.5 1.0 Heat Flow (W/g) -100 -50 0 50 100 150 Temperature (°C) Sample: BB321-DSC02 Size: 9.5000 mg Method: BB DSC File: E:\Analyses\DSC\BB321-DSC02.001 Operator: BB Run Date: 12-Jun-2018 09:37 Instrument: DSC Q100 V9.9 Build 303 Exo Up Universal V4.5A TA Instruments Bulk Synthesis of bio-based Poly(Hydroxy Urethane)s – PHUs 143 7.4. TGA analyses Figure S28: TGA trace of Run 01 Figure S29: TGA trace of Run 02 Figure S30: DSC trace of Run 03 Figure S31: DSC trace of Run 04 Figure S32: TGA trace of Run 05 Figure S33: DSC trace of Run 06 199.30°C 95.06% 304.49°C 50.00% 297.10°C 452.90°C -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Deriv. Weight (%/°C) 0 20 40 60 80 100 Weight (%) 0100 200 300 400 500 600 700 Temperature (°C) Sample: BB334-TGA01 Size: 9.1230 mg Method: TGA Dég N2 TGA File: C:...\Analyses\TGA\BB334-TGA01.001 Operator: BB Run Date: 18-Jun-2018 18:47 Instrument: TGA Q500 V20.13 Build 39 Universal V4.5A TA Instruments 205.18°C 95.06% 342.89°C 50.00% 295.77°C 339.43°C 476.81°C -0.2 0.0 0.2 0.4 0.6 Deriv. Weight (%/°C) 0 20 40 60 80 100 Weight (%) 0200 400 600 800 1000 Temperature (°C) Sample: BB314-TGA01 Size: 12.5100 mg Method: TGA Dég N2 TGA File: C:...\Analyses\TGA\BB314-TGA01.001 Operator: BB Run Date: 18-Apr-2018 16:43 Instrument: TGA Q500 V20.13 Build 39 Universal V4.5A TA Instruments 206.44°C 95.06% 378.19°C 50.00% 321.60°C 409.53°C 476.39°C -0.2 0.0 0.2 0.4 0.6 0.8 Deriv. Weight (%/°C) 0 20 40 60 80 100 Weight (%) 0200 400 600 800 1000 Temperature (°C) Sample: BB315-TGA01 Size: 11.8150 mg Method: TGA Dég N2 TGA File: C:...\Analyses\TGA\BB315-TGA01.001 Operator: BB Run Date: 18-Apr-2018 19:04 Instrument: TGA Q500 V20.13 Build 39 Universal V4.5A TA Instruments 199.61°C 95.06% 385.87°C 50.00% 211.90°C 307.97°C 447.40°C -0.2 0.0 0.2 0.4 0.6 0.8 1.0 Deriv. Weight (%/°C) 0 20 40 60 80 100 Weight (%) 0100 200 300 400 500 600 700 Temperature (°C) Sample: BB316-TGA01 Size: 14.8670 mg Method: TGA Dég N2 TGA File: C:...\Analyses\TGA\BB316-TGA01.001 Operator: BB Run Date: 19-Jun-2018 09:38 Instrument: TGA Q500 V20.13 Build 39 Universal V4.5A TA Instruments 201.23°C 95.06% 400.51°C 50.00% 213.72°C 316.88°C 446.81°C -0.2 0.0 0.2 0.4 0.6 0.8 1.0 Deriv. Weight (%/°C) 0 20 40 60 80 100 Weight (%) 0200 400 600 800 Temperature (°C) Sample: BB317-TGA01 Size: 18.3490 mg Method: TGA Dég N2 TGA File: C:...\Analyses\TGA\BB317-TGA01.001 Operator: BB Run Date: 19-Jun-2018 11:09 Instrument: TGA Q500 V20.13 Build 39 Universal V4.5A TA Instruments 250.85°C 95.06% 404.47°C 50.00% 299.23°C 466.73°C -0.2 0.0 0.2 0.4 0.6 0.8 1.0 Deriv. Weight (%/°C) 0 20 40 60 80 100 Weight (%) 0200 400 600 800 Temperature (°C) Sample: BB333-TGA01 Size: 8.0660 mg Method: TGA Dég N2 TGA File: C:...\Analyses\TGA\BB333-TGA01.001 Operator: BB Run Date: 18-Jun-2018 10:14 Instrument: TGA Q500 V20.13 Build 39 Universal V4.5A TA Instruments Chapter 2 144 Figure S34: TGA trace of Run 07 Figure S35: TGA trace of Run 08 Figure S36: DSC trace of Run 09 Figure S37: DSC trace of Run 10 Overlays a) 0200 400 600 800 0 20 40 60 80 100 Weight (%) Temperature (°C) 100% 10DA 75% 10DA 50% 10DA 25% 10DA 0% 10DA b) 0200 400 600 800 0 20 40 60 80 100 Weight (%) Temperature (°C) 100% 10DA 75% 10DA 50% 10DA 25% 10DA 0% 10DA Figure S38: TGA traces of the obtained PHUs by copolymerization of a) bisCC-C4 and b) bisCC-C10 together with various ratios of 10DA and P1075(10°C/min heating ramp) 267.08°C 95.06% 417.60°C 50.00% 291.19°C 456.69°C -0.2 0.3 0.8 1.3 Deriv. Weight (%/°C) 0 20 40 60 80 100 Weight (%) 0100 200 300 400 500 600 Temperature (°C) Sample: BB318-TGA01 Size: 12.6140 mg Method: TGA Dég N2 TGA File: C:...\Analyses\TGA\BB318-TGA01 Operator: BB Run Date: 18-Jun-2018 12:04 Instrument: TGA Q500 V20.13 Build 39 Universal V4.5A TA Instruments 265.72°C 95.06% 419.07°C 50.00% 292.25°C 452.82°C -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Deriv. Weight (%/°C) 0 20 40 60 80 100 Weight (%) 0200 400 600 800 Temperature (°C) Sample: BB319-TGA01 Size: 12.2010 mg Method: TGA Dég N2 TGA File: C:...\Analyses\TGA\BB319-TGA01.001 Operator: BB Run Date: 18-Jun-2018 13:22 Instrument: TGA Q500 V20.13 Build 39 Universal V4.5A TA Instruments 263.58°C 95.06% 426.36°C 50.00% 291.56°C 453.21°C -0.2 0.3 0.8 1.3 Deriv. Weight (%/°C) 0 20 40 60 80 100 Weight (%) 0100 200 300 400 500 600 Temperature (°C) Sample: BB320-TGA01 Size: 14.7570 mg Method: TGA Dég N2 TGA File: C:...\Analyses\TGA\BB320-TGA01.001 Operator: BB Run Date: 18-Jun-2018 15:09 Instrument: TGA Q500 V20.13 Build 39 Universal V4.5A TA Instruments 270.96°C 95.06% 428.93°C 50.00% 293.61°C 452.03°C -0.2 0.3 0.8 1.3 1.8 Deriv. Weight (%/°C) 0 20 40 60 80 100 Weight (%) 0200 400 600 800 Temperature (°C) Sample: BB321-TGA01 Size: 16.7540 mg Method: TGA Dég N2 TGA File: C:...\Analyses\TGA\BB321-TGA01.001 Operator: BB Run Date: 18-Jun-2018 16:38 Instrument: TGA Q500 V20.13 Build 39 Universal V4.5A TA Instruments Bulk Synthesis of bio-based Poly(Hydroxy Urethane)s – PHUs 145 7.5. SEC traces a) 20 30 40 -0,2 0,0 0,2 0,4 0,6 0,8 1,0 1,2 RI (-) Time (min) 100% 10DA 75% 10DA 50% 10DA 25% 10DA 0% 10DA b) 20 30 40 -0,6 -0,4 -0,2 0,0 0,2 0,4 0,6 0,8 1,0 1,2 RI (-) Time (min) 100% 10DA 75% 10DA 50% 10DA 25% 10DA 0% 10DA Figure S39 : Size exclusion traces of the obtained PHUs by copolymerization of a) bisCC-C4 or b) bisCC-C10 with various ratios of 10DA and P1075 together with (DMF, LiBr, PS Standards) 7.6. DFT Study – Structures of the intermediates Int2, prim – bisCC-C4 Int2, sec – bisCC-C4 Int2, prim – bisCC-C10 Int2, sec – bisCC-C10 Figure S 40: Structures of the Intermediates Int2, prim and Int2, sec for both bisCC-C4 and bisCC-C10 as obtained by means of DFT calculations . CHAPTER 3 MINIEMULSION OF NON-ISOCYANATE POLYURETHANE-ACRYLICS HYBRIDS AND PROPERTIES OF THE CAST FILMS THEREOF Keywords: Poly(Hydroxy)urethanes - PHUs Bio-based Polymers NIPUs PU-Acrylic Hybrid Miniemulsion Coatings Chapter 3 148 Table of content 1. Introduction ......................................................................................................................................... 149 2. Experimental ........................................................................................................................................ 150 2.1. Materials ...................................................................................................................................... 150 2.2. Experimental design ............................................................................................................... 150 2.3. Miniemulsification and miniemulsion polymerization ............................................ 151 2.4. Film casting ................................................................................................................................. 152 2.5. Characterization ....................................................................................................................... 153 3. Results and Discussion .................................................................................................................... 155 4. Conclusions ........................................................................................................................................... 165 5. References ............................................................................................................................................. 166 6. Shortened forms ................................................................................................................................. 169 7. Supporting Information................................................................................................................... 170 7.1. Side Reactions ............................................................................................................................ 170 7.2. Solubility ...................................................................................................................................... 175 7.3. Miniemulsion polymerization using thermal initiators ........................................... 179 7.3.1. Formulations with thermal initiators ......................................................................... 179 7.3.2. Results and discussion ...................................................................................................... 182 7.4. Formulations with redox initiators................................................................................... 184 7.5. SEC-MALLS Traces ................................................................................................................... 187 7.6. DSC Traces ................................................................................................................................... 188 7.7. Minimum Film Forming Temperature (MMFT) .......................................................... 189 Miniemulsion polymerization of Non-Isocyanate Polyurethane-Acrylics Hybrids via and properties of the cast films thereof 149 1. Introduction Accessing high performance polymer materials with satisfactory properties and balanced production cost usually requires the synergistic combination of polymers with different and even antagonist properties. Hybrids of polyurethanes (PU) and (meth)acrylic polymers is one of these synergistic combinations. PUs provide superior mechanical properties such as toughness, flexibility and abrasion resistance,1–4 whereas poly(meth)acrylics are affording materials with good outdoor and alkali resistance, as well as pigment compatibility.4–6 PU-(meth)acrylic hybrids are often prepared as waterborne dispersions that find applications as coatings and adhesives. The field has been recently reviewed aiming at establishing the link between synthesis, structure and properties.7 The final outlook of that review points out the challenges created by the environmental impacts of both the raw materials used in the synthesis and the need of developing low VOC and preferably VOC-free synthetic routes. Currently, di-isocyanates are used in the PU synthesis, but they may cause health issues such as asthma, dermatitis and even poisoning.8–10 In addition isocyanates require the use of phosgene in their synthesis and this is a highly toxic gas that can cause death by inhalation. Solvent free PU-(meth)acrylic hybrids have been obtained by synthesizing the PU prepolymer using a mixture of (meth)acrylic monomers as diluents and then dispersing the solution in water.11–17 However, achieving good colloidal stability is challenging and requires fine tuning of the synthetic approach.18 This chapter addresses the challenge of synthesizing isocyanate-free, solvent-free waterborne PU-(meth)acrylic dispersions. The field of water-based non-isocyanate polyurethanes (NIPUs) and polyureas (NIPUUs) has been reviewed in Chapter 1. This review shows that there are only two publications on the synthesis of waterborne NIPUacrylic dispersions.19,20 In these works, monofunctional urethane methacrylates (UMA) were prepared by aminolysis of ethylene carbonate and aliphatic amines in methylene chloride and then the resulting product was functionalized with methacrylic anhydride in DMF. The UMAs were copolymerized with MMA/BA in a seeded emulsion polymerization. The method presents some drawbacks as it involves several steps and uses solvents. Furthermore, the hybrids do not contained poly(urethane) chains, but urethane moieties. In order to overcome these drawbacks in this chapter two complementary strategies were explored. The first one involved the formation of the isocyanate-free polymer by aminolysis of cyclic-carbonate derivatives using (meth)acrylic monomers as reacting media. This process leads to poly(hydroxy urethane)s – often called PHU.21–23 The idea was to disperse the PHU/(meth)acrylates solution in water through a miniemulsification process, and then polymerize the (meth)acrylic monomers by free radical polymerization. Chapter 3 150 It will be shown that this at first sight promising idea encounters several serious problems. The second strategy explored was first to form the PHUs by bulk aminolysis of cyclic-carbonate derivatives using bio-sourced vegetable oil-based diamines. Then, the PHU was dissolved in (meth)acrylate monomers and the solution used as the organic phase of a miniemulsion. Subsequent polymerization of the (meth)acylic monomers led to the hybrid PU/(meth)acrylates waterborne dispersion. The performance of the films cast from the hybrid waterborne dispersions was studied. 2. Experimental 2.1. Materials 1,4-butanediamine (4DA, >98%), decane 1,10-diamine (10DA, >98%) and 1,12diaminododecane (12DA, >98%) were supplied by TCI Europe. 1,6-haxanediamine (6DA, >99%) was obtained from Accros. 1,3-cyclohexanebis(methylamine) (CycloDA, 98%), butyl acetate (BAc, >99%), Butyl acrylate (BA, >99%), butyl methacrylate (BMA, 99%), stearyl acrylate SA, %, ,-azobis(2-methylpropionitrile) (AIBN, 98%) and tert-butyl hydroperoxide (TBHP, 70% in water) were obtained from Sigma. Ascorbic acid (or Vitamin C, AsA, >99.5%) was obtained from Fluka. Croda kindly provided PriamineTM 1075 (P1075). Dow kindly provided alkyl diphenyl oxide disulfonate (DowfaxTM 2A1, D2A1, 45wt% in water). One cyclic carbonates, bisCC-C10, was used. The synthesis of this carbonate is detailed in Chapter 2. All products and solvents (reagent grade) were used as received unless otherwise mentioned. Deionized water was used. 2.2. Experimental design As explained in the introduction two synthetic strategies were explored. The first one involves the polymerization of the cyclic carbonates and diamines in (meth)acrylic monomers, followed by dispersion in water and subsequent free radical polymerization of the (meth)acrylates. As amines can potentially react with acrylic monomers, typically in an aza-Michaeltype mechanism, the occurrence of this reaction was checked. It was found that BA suffered a significant reaction with the amines (Supporting Information – Figures S1 to S4). This is a strong drawback because side reactions consuming diamines will modify the stoichiometry substantially reducing the molecular weight of the polymer formed by this step-growth polymerization. Although BMA was only slightly affected by this reaction (Supporting Information – Figures S5 to S6), the strategy based on the formation of PHU in (meth)acrylates was abandoned and efforts were concentrated in the second strategy that involved the formation of the PHUs by bulk aminolysis of bis-cyclic-carbonate derivatives using bio-sourced vegetable oil-based diamines followed by dissolution of the Miniemulsion polymerization of Non-Isocyanate Polyurethane-Acrylics Hybrids via and properties of the cast films thereof 151 PHUs in (meth)acrylic monomers, dispersion in water to form a miniemulsion, and free radical polymerization of the vinyl monomers. Miniemulsion polymerization was used because this process is particularly well suited for the synthesis of hybrid dispersions.24,25 Poly(hydroxy)urethanes (PHUs) were synthesized through the aminolysis reaction between bisCC-C10 and P1075 (Figure 1). The stoichiometric ratio for the reactive moieties was used to target high molar masses according to the Carothers theory.26 The reactions were performed in bulk at 90°C for 24h in a Schlenk tube using a helical shaped mechanical stirrer specifically designed to fit in the Schlenk vessel. No catalyst was added for the polymerization reactions. No purification of the PHUs was performed after reaction. Figure 1: PHU pre-polymer utilized for the synthesis of PHU-Acrylics hybrid materials A necessary condition for the implementation of the second approach is that the PHU should be soluble in the (meth)acrylates. Therefore, the solubility of the PHUs obtained with a series of cyclic carbonates and diamines in butyl methacrylate (BMA) was determined. As shown in Supporting Information (Section 6.2), the solubility of the cyclic carbonates and diamines in BMA was low (most of the diamines checked were not soluble for formulations targeting 10wt% of PHU in BMA) although the solubility could be improved using P1075. 2.3. Miniemulsification and miniemulsion polymerization The formulations used are summarized in Supporting Information (Tables S3 to S8 and Table S10 to S13). The organic phase of the miniemulsion was prepared by dissolving P1075-based PHU (0 to 30 wt.% weight based on BMA) in a mixture of BMA and SA (4 wt% of SA) at 80°C. The aqueous phase was a 1 wt% (based on the total organic phase) solution of Dowfax2A1 in deionized water. The organic phase was added drop-wise into the aqueous phase under vigorous magnetic stirring. Then, the miniemulsion was formed by sonicating the coarse emulsion for 30 min with a Hielscher Ultrasonics GmbH (ref UIS250V) using an amplitude of 100% and 0.8s duty cycle. A post-stabilization step is performed by adding 1 wt.% of Dowfax 2A1 based on the total organic phase dissolved in a minimum amount of deionized water. The miniemulsion was transferred to a 3-neck round-bottom flask and flushed with nitrogen during 30 min at 70°C. Then, the initiator was added in a way that depended on the type of initiator. The performance of thermal initiators was first checked using AIBN