Nanostructuring Biobased Epoxy Resin with PEO-PPO-PEO Block Copolymer

Ci a ion: Ba andia an, I.;
Gomez-He moso-de-Mendoza, J.;
Gu ie ez, J.; Te cjak, A.; Ko abe ia,
G. Nanos uc u ing Biobased Epoxy
Resin wi h PEO-PPO-PEO Block
Copolyme . Polyme s 2023,15, 1216.
h ps://doi.o g/10.3390/
polym15051216
Academic Edi o : As e ios
(S e gios) Pispas
Recei ed: 1 Feb ua y 2023
Re ised: 23 Feb ua y 2023
Accep ed: 24 Feb ua y 2023
Published: 28 Feb ua y 2023
Copy igh : © 2023 by he au ho s.
Licensee MDPI, Basel, Swi ze land.
This a icle is an open access a icle
dis ibu ed unde he e ms and
condi ions o he C ea i e Commons
A ibu ion (CC BY) license (h ps://
c ea i ecommons.o g/licenses/by/
4.0/).
polyme s
A icle
Nanos uc u ing Biobased Epoxy Resin wi h PEO-PPO-PEO
Block Copolyme
I a i Ba andia an 1,2, Joseba Gomez-He moso-de-Mendoza 1, Junkal Gu ie ez 1, Agnieszka Te cjak 1
and Galde Ko abe ia 1,*
1G oup ‘Ma e ials + Technologies’ (GMT), Chemical and En i onmen al Enginee ing Depa men ,
Facul y o Enginee ing o Gipuzkoa, Uni e si y o he Basque Coun y (UPV/EHU), Plaza Eu opa 1,
20018 Donos ia-San Sebas ian, Spain
2Chemical and En i onmen al Enginee ing Depa men , Facul y o Pha macy, Uni e si y o he Basque
Coun y (UPV/EHU), Paseo de la Uni e sidad, 7, 01006 Vi o ia-Gas eiz, Spain
*Co espondence: galde [email p o ec ed]
Abs ac :
A biobased diglycidyl e he o anillin (DGEVA) epoxy esin was nanos uc u ed by
poly(e hylene oxide-b-p opylene oxide-b-e hylene oxide) (PEO-PPO-PEO) iblock copolyme . Due
o he miscibili y/immiscibili y p ope ies o he iblock copolyme in DGEVA esin, di e en
mo phologies we e ob ained depending on he iblock copolyme amoun . A hexagonally packed
cylinde mo phology was kep un il eaching 30 w % o PEO-PPO-PEO con en , while a mo e complex
h ee-phase mo phology was ob ained o 50 w %, in which la ge wo m-like PPO domains appea
su ounded by wo di e en phases, one o hem ich in PEO and ano he phase ich in cu ed DGEVA.
UV- is measu emen s show ha he ansmi ance is educed wi h he inc ease in iblock copolyme
con en , especially a 50 w %, p obably due o he p esence o PEO c ys als de ec ed by calo ime y.
Keywo ds: biobased; epoxy; block copolyme ; nanos uc u ing
1. In oduc ion
Du ing ecen yea s, bio-based polyme s ha e a ac ed a en ion due o he o e use
o ossil uels as well as he inc ease in g eenhouse gas emissions, which causes impo an
en i onmen al issues [
1
,
2
]. Those polyme s can be ob ained om enewable ma e ials, such
as lignin [
3
] o ege able oils [
4
,
5
], among o he s. Be ween hese di e en ypes o polyme ic
ma e ials, epoxy-based he mose s a e he mos popula , due o hei b oad spec um o
p ope ies h ough he selec ion o epoxy p epolyme s and cu ing agen s, and he e o e
hei use in a ious applica ions, such as coa ings, adhesi es, and composi es, among
o he s [
6
–
8
]. O e 90% o hese epoxide ma e ials a e based on bis(4-hyd oxyphenylene)-
2,2-p opane, known as bisphenol A, o which he a oma ic ing con e s good he mal
esis ance. Comme cialized o mo e han 50 yea s, hese bisphenol A based he mose s
(DGEBA) ha e been employed in many common p oduc s, such as con aine s, and human
heal h applica ions, such as illing ma e ials o sealan s in den is y. Howe e , bisphenol
A can also mimic he body’s own ho mones, and i could lead o se e e nega i e heal h
e ec s [
9
,
10
], besides ci ed en i onmen al issues. Recen ly, poly- unc ional glycidyl e he
de i a i es based on bo h biobased and ba ely oxic ex ac s, such as anillin [
11
–
15
] and
phlo oglucinol [
16
–
18
], which a e ex ac ed om lignins and annins [
1
,
19
], and used as
ood la o ing o ac i e ing edien in medicine, ha e been s udied as new eeds ock o
he mose s. Be ween di e en biobased esins in es iga ed by o he au ho s, diglycidyl
e he o anillin (DGEVA) ha e shown good he momechanical p ope ies [20,21].
On he o he hand, he sel -assembly o block copolyme s (BCP) in o di e en nanoscale
s uc u es makes hem in e es ing polyme ic mac omolecules om bo h academic and
indus ial poin s o iew. This class o mac omolecules consis s o wo o mo e co alen ly
linked polyme s, which a e he modynamically incompa ible, gi ing ise o a a ie y o he
Polyme s 2023,15, 1216. h ps://doi.o g/10.3390/polym15051216 h ps://www.mdpi.com/jou nal/polyme s
Polyme s 2023,15, 1216 2 o 13
mic os uc u es. As i is well known, BCPs can sel -assemble o o m nanoscale s uc u es
wi h domain spacing ha depends s ongly on molecula weigh , segmen size and in e ac-
ion be ween he blocks among o he s. Consequen ly, mic ophase sepa a ion o BCPs is
de e mined by he deg ee o polyme iza ion, N, he olume ac ion o each block, , and
he Flo y–Huggins in e ac ion pa ame e ,
χ
, which depends on empe a u e. A ypical size
o he mic ophase sepa a ed BCP domains is in he ange o 10–200 nm.
BCPs can mic ophase sepa a ed in s able s uc u es, such as lamella , hexagonal-
packed cylinde , body-cen e ed cubic, close-packed sphe ical, o bicon inuous cubic gy oid
s uc u es. The abili y o con ol bo h he leng h scale and he spa ial o ganiza ion o BCP
mo phologies makes hese polyme ic ma e ials a ac i e candida es o use as empla es
o he ab ica ion o no el mul i unc ional ma e ials wi h applica ion in many ields o
nano echnology and ad anced ma e ials.
BCPs can also ac as a nanos uc u ing agen o di e en homopolyme s and he -
mose ing sys ems. As he main d awback o epoxy he mose ing polyme s, o hei
applica ions as adhesi es, su ace coa ings o composi e ma ices, is hei low ac u e
oughness. One o he success ul pa hways o achie e high imp o emen s on he oughness
o hese sys ems is inco po a ion o BCPs [
22
–
26
]. Use o he BCPs no only imp o es he
oughness o he mose ing polyme s bu also leads o nanos uc u ed he mose s, which
can ac as empla es o dispe sion and selec i e localiza ion o low molecula weigh
o ganic molecules, such as azobenzene o liquid c ys als, o ino ganic nanoobjec s, such as
nanopa icles, ca bon nano ubes, nano ibe s and o he s.
Nanos uc u ed he mose ing ma e ials can be o med ollowed wo di e en mecha-
nisms. In he i s one, he epoxy p ecu so ac s as a selec i e sol en and, consequen ly,
he mic ophase sepa a ion akes place be o e he cu ing eac ion, and he epoxy ne wo k
o ma ion p ocess only ixed he inal mo phology. In he second pa hway, he mic ophase
sepa a ion o he immiscible block akes place by eac ion-induced phase sepa a ion (RIPS).
Thus, he mix u e o BCP and epoxy p ecu so s is miscible be o e cu ing and he phase
sepa a ion akes place du ing ne wo k o ma ion.
Many au ho s, among which ou esea ch g oup can be men ioned, ob ained nanos-
uc u ed he mose ing sys ems by employing amphiphilic BCPs. Di e en amphiphilic
BCPs used as nanos uc u ing agen s by di e en au ho s can be ound in Table 1.
Table 1.
Rela ion o di e en amphiphilic block copolyme s and he mose ing p ecu so s used by
di e en au ho s.
BCPs Abb e ia ion The mose ing
P ecu so Re e ences
poly(hexylene oxide)-b-poly(e hylene oxide) PHO-b-PEO DGEBA + PN [24]
poly(e hylene oxide)-b-poly(e hyl e hylene) PEO-b-PEE DGEBA + PA [27]
poly(e hylene oxide)-b-poly(e hylene-al -p opylene) PEO-b-PEP DGEBA + MDA [28]
poly(e hylene oxide)-b-poly(p opylene oxide) PEO-b-PPO DGEBA + MDA [29]
poly(e hylene oxide)-b-poly(p opylene oxide)-b- poly(e hylene oxide) PEO-b-PPO-b-PEO DGEBA + MDA
DGEBA + DDM
[30,31]
[32–35]
polye hylene-b-poly(e hylene oxide) PE-b-PEO DGEBA + MDA
DGEBA + MCDEA
[36]
[37]
poly(e hylene oxide)-b-poly(dime hylsiloxane) PEO-b-PDMS DGEBA + MDA [38]
poly(e hylene oxide)-b-poly(ε-cap olac one) PEO-b-PCL DGEBA + MOCA [39]
poly(e hylene oxide)-b-polys y ene PEO-b-PS
DGEBA + MDA
DGEBA + MXDA
DGEBA + MCDEA
DGEBA + DDM
[40]
[41–44]
[45,46]
[47]
Polyme s 2023,15, 1216 3 o 13
Table 1. Con .
BCPs Abb e ia ion The mose ing
P ecu so Re e ences
poly(ε-cap olac one)-b-polybu adiene-b-poly(ε-cap olac one) PCL-b-PB-b-PCL DGEBA + MOCA [48]
poly(ε-cap olac one)-b-poly(n-bu yl ac yla e) PCL-b-PBA DGEBA + MOCA [49]
poly(hep adeca luo odecyl ac yla e)-b-poly(cap olac one) PaF-b-PCL
DGEBA + MCDEA
[50]
polydime hylsiloxane-b-poly(ε-cap olac one)-b-polys y ene PDMS-b-PCL-b-PS DGEBA + MOCA [51]
poly(ε-cap olac one)-b-polys y ene PCL-b-PS DGEBA + MOCA [52]
As i can be seen in Table 1, poly(e hylene glycol)-poly(p opylene glycol)-poly(e hyleneglycol)
(PEO-PPO-PEO), has been widely employed o nanos uc u ing epoxy ma ices, mainly
DGEBA esin [
30
–
35
]. The popula i y o PEO-PPO-PEO is due o i s comme cial a ailabili y,
including di e en a ios o each block as well as he simplici y o he expe imen al p oce-
du e and he absence o any chemical syn hesis o eac ion wi h he epoxy sys em [
32
]. Fo
PEO-PPO-PEO/epoxy blends, he o ma ion o he sel -assembled nanos uc u e depends
on he cu ing condi ions, cu ing agen and he inne cha ac e is ics o he BCP [
53
]. Rega d-
ing he e ec o BCP composi ion, Guo e al. [
30
] ob ained di e en nanos uc u ed ea u es
based on he DGEBA/MDA sys em and PPO-PEO-PPO copolyme s wi h di e en block
a ios. Fo he BCP wi h 30 w % o PEO block, i did no ind mac oscopic phase sepa a ion
up o a con en o 50 w %, exhibi ing nanos uc u es based on sphe ical PPO domains
wi h an a e age size o abou 10 nm. Fo blends wi h he BCP wi h 80 w % PEO, blends
we e no mac oscopically phase-sepa a ed o e he en i e composi ion ange because o he
much highe PEO con en , showing composi ion-dependen nanos uc u es on he o de o
10
−
100 nm. Sun e al. [
31
] s udied he same sys ems by solid-s a e nuclea magne ic eso-
nance (NMR), inding ha he domain size and long pe iod depended s ongly on he PEO
ac ion. They demons a ed ha PEO blocks we e only pa ially miscible wi h he cu ed
ne wo k. Upon cu ing, he c oss-linked igid epoxy esin o med a sepa a ed mic ophase,
while some PEO we e locally expelled ou o he cu ed ne wo k, o ming ano he mi-
c ophase wi h PPO. Simila sys ems bu employing diamino diphenyl me hane (DDM) as a
ha dene ha e also been deeply analyzed by ou g oup [
32
–
35
]. Fi s ly, he miscibili y and
mo phological ea u es we e s udied, oge he wi h cu e kine ics, by changing cu e empe -
a u es and copolyme amoun [
32
]. Depending on he cu ing condi ion, phase sepa a ion
ook place a mic o o nanoscale due o compe i ion among kine ic and he modynamic
ac o s. Two dis inc phases we e p esen o e e y blend s udied excep o he sys em
wi h 10 w % PEO–PPO–PEO and cu ed a a low empe a u e. A he modynamic model de-
sc ibing a he mose /block copolyme conside ed as only one en i y sys em was p oposed.
In a second s age, he e ec o copolyme composi ion (block a ios) and cu ing condi ions
was analyzed [
33
]. A delay o cu e a e was ound, which inc eased as copolyme con en
and PEO mola a io in he block copolyme inc eased. In a ed spec oscopy showed ha
PEO block was mainly esponsible o physical in e ac ions be ween he hyd oxyl g oups
o g owing epoxy he mose and e he bonds o block copolyme ha led o he delay in
cu e kine ics. Rega ding s uc u al cha ac e iza ion [
34
], aking in o accoun DGEBA/DDM
sys ems modi ided wi h PEO o PPO homopolyme s o compa ison, i was ound ha ,
depending on he mola a io among blocks, mic o o mac ophase sepa a ed mo phologies
we e ob ained. Fo high mola a io among blocks, mic ophase-sepa a ed s uc u es we e
ob ained o all block copolyme con en s and cu e empe a u es, wi h he sel -assembly
o PPO in o nanoscopic en i ies. Fo low mola a io among blocks, howe e , he physical
in e ac ions among he PEO block and he epoxy ma ix we e no a ou able enough, due
o he lowe con en o his block. Indeed, he micelles o med ini ially coalesced, leading o
mac oscopic phase sepa a ion, whe e di e en mo phologies we e ob ained depending on
copolyme con en and cu e empe a u e. Finally, he mechanical p ope ies–mo phology
ela ionships we e also analyzed [
35
]. Mac ophase-sepa a ed sys ems modi ied wi h low
PEO/PPO block a io showed a simila beha iou o ha o ubbe -modi ied sys ems.
Polyme s 2023,15, 1216 4 o 13
Inc easing he con en o a modi ie dec eases bo h lexu al modulus and s eng h, while
ac u e oughness inc eases. Mic ophase-sepa a ed sys ems, on he o he hand, did no
p esen signi ican changes in bo h lexu al modulus and s eng h o low con en s, bu he
c i ical s ess in ensi y ac o inc eased due o pa ial miscibili y o he PEO block wi h he
epoxy ma ix.
Pa ameswa anpillai e al. [
54
] nanos uc u ed a DGEBA/DDM sys em wi h PEO-
PPO-PEO, inding ha he phase sepa a ion occu ed ia sel -assembly o PPO blocks,
ollowed by he eac ion-induced phase sepa a ion o PEO blocks, and con i ming ha
phase sepa a ed PEO blocks o med he c ys alline phase in he amo phous c osslinked
epoxy ma ix.
In he p esen wo k, as a p elimina y s udy o analyzing he nanos uc u ing o
bio-based epoxy he mose ing o mula ion, DGEVA epoxy esin has been modi ied us-
ing di e en amoun s o PEO-PPO-PEO iblock copolyme anging om 10 o 50 w %.
The mal p ope ies a e analyzed in e ms o di e en ial scanning calo ime y (DSC) and
he mog a ime ic analysis (TGA), while op ical p ope ies a e cha ac e ized by UV- is
spec oscopy and co obo a ed by pho og aphs. Finally, he e ec o copolyme amoun
on he mo phology o he nanos uc u ed he mose ing sys em is analyzed by a omic
o ce mic oscopy (AFM). The possibili y o nanos uc u ing and he con ol o gene a ed
nanos uc u es will be u he employed in u u e wo ks o he p epa a ion o e na y
sys ems based on biobased epoxy he mose s by placing nano ille s a he nanodomains.
2. Ma e ials and Me hods
2.1. Ma e ials and Sample P epa a ion
The biobased epoxy used in his esea ch wo k was diglycidyl e he o anillin
(DGEVA) supplied by Speci ic Polyme s, Cas ies, F ance. The cu ing agen was 4,4
0
-
diaminodiphenylme hane (DDM), pu chased om Sigma-Ald ich, Da ms ad , Ge many.
The block copolyme used was poly(e hylene oxide-b-p opylene oxide-b-e hylene ox-
ide) (PEO-PPO-PEO) iblock copolyme (Plu onic F-127) supplied by Sigma Ald ich,
Da ms ad , Ge many. Chemical s uc u es o employed ma e ials a e shown in Table 2.
An amine:epoxy a io o 1:1 was used o he DGEVA/DDM sys em, while PEO-PPO-
PEO block copolyme con en was a ied om 10 o 50 w % o design di e en BCP-
DGEVA/DDM sys ems.
Table 2. Chemical s uc u es o employed ma e ials.
Ma e ial Chemical S uc u e
DGEVA
Polyme s 2023, 14, x FOR PEER REVIEW 4 o 13
di e en mo phologies we e ob ained depending on copolyme con en and cu e
empe a u e. Finally, he mechanical p ope ies–mo phology ela ionships we e also
analyzed [35]. Mac ophase-sepa a ed sys ems modi ied wi h low PEO/PPO block a io
showed a simila beha iou o ha o ubbe -modi ied sys ems. Inc easing he con en
o a modi ie dec eases bo h lexu al modulus and s eng h, while ac u e oughness
inc eases. Mic ophase-sepa a ed sys ems, on he o he hand, did no p esen signi ican
changes in bo h lexu al modulus and s eng h o low con en s, bu he c i ical s ess
in ensi y ac o inc eased due o pa ial miscibili y o he PEO block wi h he epoxy
ma ix.
Pa ameswa anpillai e al. [54] nanos uc u ed a DGEBA/DDM sys em wi h
PEO-PPO-PEO, inding ha he phase sepa a ion occu ed ia sel -assembly o PPO
blocks, ollowed by he eac ion-induced phase sepa a ion o PEO blocks, and con i ming
ha phase sepa a ed PEO blocks o med he c ys alline phase in he amo phous
c osslinked epoxy ma ix.
In he p esen wo k, as a p elimina y s udy o analyzing he nanos uc u ing o
bio-based epoxy he mose ing o mula ion, DGEVA epoxy esin has been modi ied
using di e en amoun s o PEO-PPO-PEO iblock copolyme anging om 10 o 50 w %.
The mal p ope ies a e analyzed in e ms o di e en ial scanning calo ime y (DSC) and
he mog a ime ic analysis (TGA), while op ical p ope ies a e cha ac e ized by UV- is
spec oscopy and co obo a ed by pho og aphs. Finally, he e ec o copolyme amoun
on he mo phology o he nanos uc u ed he mose ing sys em is analyzed by a omic
o ce mic oscopy (AFM). The possibili y o nanos uc u ing and he con ol o gene a ed
nanos uc u es will be u he employed in u u e wo ks o he p epa a ion o e na y
sys ems based on biobased epoxy he mose s by placing nano ille s a he nanodomains.
2. Ma e ials and Me hods
2.1. Ma e ials and Sample P epa a ion
The biobased epoxy used in his esea ch wo k was diglycidyl e he o anillin
(DGEVA) supplied by Speci ic Polyme s, Cas ies, F ance. The cu ing agen was
4,4′-diaminodiphenylme hane (DDM), pu chased om Sigma-Ald ich, Da ms ad ,
Ge many. The block copolyme used was poly(e hylene oxide-b-p opylene ox-
ide-b-e hylene oxide) (PEO-PPO-PEO) iblock copolyme (Plu onic F-127) supplied by
Sigma Ald ich, Da ms ad , Ge many. Chemical s uc u es o employed ma e ials a e
shown in Table 2. An amine:epoxy a io o 1:1 was used o he DGEVA/DDM sys em,
while PEO-PPO-PEO block copolyme con en was a ied om 10 o 50 w % o design
di e en BCP-DGEVA/DDM sys ems.
Table 2. Chemical s uc u es o employed ma e ials.
Ma e ial Chemical S uc u e
DGEVA
DDM
PEO-PPO-PEO
Sample p epa a ion was ca ied ou in he ollowing way. Fi s , DGEVA esin and
PEO–PPO–PEO iblock copolyme we e blended a 80 °C unde mechanic s i ing. Then,
a co esponding amoun o DDM was added wi h con inuous s i ing, in an oil ba h a 80
°C, un il a homogeneous mix u e was achie ed. Finally, he mix u e was pou ed o he
DDM
Polyme s 2023, 14, x FOR PEER REVIEW 4 o 13
di e en mo phologies we e ob ained depending on copolyme con en and cu e
empe a u e. Finally, he mechanical p ope ies–mo phology ela ionships we e also
analyzed [35]. Mac ophase-sepa a ed sys ems modi ied wi h low PEO/PPO block a io
showed a simila beha iou o ha o ubbe -modi ied sys ems. Inc easing he con en
o a modi ie dec eases bo h lexu al modulus and s eng h, while ac u e oughness
inc eases. Mic ophase-sepa a ed sys ems, on he o he hand, did no p esen signi ican
changes in bo h lexu al modulus and s eng h o low con en s, bu he c i ical s ess
in ensi y ac o inc eased due o pa ial miscibili y o he PEO block wi h he epoxy
ma ix.
Pa ameswa anpillai e al. [54] nanos uc u ed a DGEBA/DDM sys em wi h
PEO-PPO-PEO, inding ha he phase sepa a ion occu ed ia sel -assembly o PPO
blocks, ollowed by he eac ion-induced phase sepa a ion o PEO blocks, and con i ming
ha phase sepa a ed PEO blocks o med he c ys alline phase in he amo phous
c osslinked epoxy ma ix.
In he p esen wo k, as a p elimina y s udy o analyzing he nanos uc u ing o
bio-based epoxy he mose ing o mula ion, DGEVA epoxy esin has been modi ied
using di e en amoun s o PEO-PPO-PEO iblock copolyme anging om 10 o 50 w %.
The mal p ope ies a e analyzed in e ms o di e en ial scanning calo ime y (DSC) and
he mog a ime ic analysis (TGA), while op ical p ope ies a e cha ac e ized by UV- is
spec oscopy and co obo a ed by pho og aphs. Finally, he e ec o copolyme amoun
on he mo phology o he nanos uc u ed he mose ing sys em is analyzed by a omic
o ce mic oscopy (AFM). The possibili y o nanos uc u ing and he con ol o gene a ed
nanos uc u es will be u he employed in u u e wo ks o he p epa a ion o e na y
sys ems based on biobased epoxy he mose s by placing nano ille s a he nanodomains.
2. Ma e ials and Me hods
2.1. Ma e ials and Sample P epa a ion
The biobased epoxy used in his esea ch wo k was diglycidyl e he o anillin
(DGEVA) supplied by Speci ic Polyme s, Cas ies, F ance. The cu ing agen was
4,4′-diaminodiphenylme hane (DDM), pu chased om Sigma-Ald ich, Da ms ad ,
Ge many. The block copolyme used was poly(e hylene oxide-b-p opylene ox-
ide-b-e hylene oxide) (PEO-PPO-PEO) iblock copolyme (Plu onic F-127) supplied by
Sigma Ald ich, Da ms ad , Ge many. Chemical s uc u es o employed ma e ials a e
shown in Table 2. An amine:epoxy a io o 1:1 was used o he DGEVA/DDM sys em,
while PEO-PPO-PEO block copolyme con en was a ied om 10 o 50 w % o design
di e en BCP-DGEVA/DDM sys ems.
Table 2. Chemical s uc u es o employed ma e ials.
Ma e ial Chemical S uc u e
DGEVA
DDM
PEO-PPO-PEO
Sample p epa a ion was ca ied ou in he ollowing way. Fi s , DGEVA esin and
PEO–PPO–PEO iblock copolyme we e blended a 80 °C unde mechanic s i ing. Then,
a co esponding amoun o DDM was added wi h con inuous s i ing, in an oil ba h a 80
°C, un il a homogeneous mix u e was achie ed. Finally, he mix u e was pou ed o he
PEO-PPO-PEO
Polyme s 2023, 14, x FOR PEER REVIEW 4 o 13
di e en mo phologies we e ob ained depending on copolyme con en and cu e
empe a u e. Finally, he mechanical p ope ies–mo phology ela ionships we e also
analyzed [35]. Mac ophase-sepa a ed sys ems modi ied wi h low PEO/PPO block a io
showed a simila beha iou o ha o ubbe -modi ied sys ems. Inc easing he con en
o a modi ie dec eases bo h lexu al modulus and s eng h, while ac u e oughness
inc eases. Mic ophase-sepa a ed sys ems, on he o he hand, did no p esen signi ican
changes in bo h lexu al modulus and s eng h o low con en s, bu he c i ical s ess
in ensi y ac o inc eased due o pa ial miscibili y o he PEO block wi h he epoxy
ma ix.
Pa ameswa anpillai e al. [54] nanos uc u ed a DGEBA/DDM sys em wi h
PEO-PPO-PEO, inding ha he phase sepa a ion occu ed ia sel -assembly o PPO
blocks, ollowed by he eac ion-induced phase sepa a ion o PEO blocks, and con i ming
ha phase sepa a ed PEO blocks o med he c ys alline phase in he amo phous
c osslinked epoxy ma ix.
In he p esen wo k, as a p elimina y s udy o analyzing he nanos uc u ing o
bio-based epoxy he mose ing o mula ion, DGEVA epoxy esin has been modi ied
using di e en amoun s o PEO-PPO-PEO iblock copolyme anging om 10 o 50 w %.
The mal p ope ies a e analyzed in e ms o di e en ial scanning calo ime y (DSC) and
he mog a ime ic analysis (TGA), while op ical p ope ies a e cha ac e ized by UV- is
spec oscopy and co obo a ed by pho og aphs. Finally, he e ec o copolyme amoun
on he mo phology o he nanos uc u ed he mose ing sys em is analyzed by a omic
o ce mic oscopy (AFM). The possibili y o nanos uc u ing and he con ol o gene a ed
nanos uc u es will be u he employed in u u e wo ks o he p epa a ion o e na y
sys ems based on biobased epoxy he mose s by placing nano ille s a he nanodomains.
2. Ma e ials and Me hods
2.1. Ma e ials and Sample P epa a ion
The biobased epoxy used in his esea ch wo k was diglycidyl e he o anillin
(DGEVA) supplied by Speci ic Polyme s, Cas ies, F ance. The cu ing agen was
4,4′-diaminodiphenylme hane (DDM), pu chased om Sigma-Ald ich, Da ms ad ,
Ge many. The block copolyme used was poly(e hylene oxide-b-p opylene ox-
ide-b-e hylene oxide) (PEO-PPO-PEO) iblock copolyme (Plu onic F-127) supplied by
Sigma Ald ich, Da ms ad , Ge many. Chemical s uc u es o employed ma e ials a e
shown in Table 2. An amine:epoxy a io o 1:1 was used o he DGEVA/DDM sys em,
while PEO-PPO-PEO block copolyme con en was a ied om 10 o 50 w % o design
di e en BCP-DGEVA/DDM sys ems.
Table 2. Chemical s uc u es o employed ma e ials.
Ma e ial Chemical S uc u e
DGEVA
DDM
PEO-PPO-PEO
Sample p epa a ion was ca ied ou in he ollowing way. Fi s , DGEVA esin and
PEO–PPO–PEO iblock copolyme we e blended a 80 °C unde mechanic s i ing. Then,
a co esponding amoun o DDM was added wi h con inuous s i ing, in an oil ba h a 80
°C, un il a homogeneous mix u e was achie ed. Finally, he mix u e was pou ed o he
Sample p epa a ion was ca ied ou in he ollowing way. Fi s , DGEVA esin and
PEO–PPO–PEO iblock copolyme we e blended a 80
◦
C unde mechanic s i ing. Then,
a co esponding amoun o DDM was added wi h con inuous s i ing, in an oil ba h a
80
◦
C, un il a homogeneous mix u e was achie ed. Finally, he mix u e was pou ed o
he mold, and samples we e degassed in a acuum o en and cu ed a 120
◦
C o 6 h and
pos -cu ed unde acuum a 190
◦
C o 2 h. In bo h cases, a mechanical acuum pump
de ice was employed.
Polyme s 2023,15, 1216 5 o 13
2.2. Techniques
Di e en ial scanning calo ime y (DSC) measu emen s o he indi idual componen s,
as well as BCP-DGEVA/DDM sys ems, we e pe o med using a DSC3+ om Me le
Toledo equipmen (Columbus, OH, USA). The mal beha io o indi idual componen s
and he DGVA/DDM sys em was e alua ed by dynamic scans pe o med om
−
80
◦
C o
250 ◦C
a 10
◦
C/min scan a e. The miscibili y o PEO–PPO–PEO iblock copolyme wi h
he uncu ed DGEVA/DDM sys em was in es iga ed by dynamic scans pe o med om
−80 ◦C
o 50
◦
C a 10
◦
C/min scan a e. The cu ing p ocesses o all BCP-DGEVA/DDM
sys ems we e analyzed by iso he mal scan pe o med a 80, 100 and 120
◦
C ( ollowed by
a dynamic scan om 25
◦
C o 200
◦
C a 10
◦
C/min). Finally, he mal beha io o BCP-
DGEVA/DDM sys ems was analyzed by dynamic scans pe o med om
−
80
◦
C o 250
◦
C
a 10
◦
C/min scan a e. All expe imen s we e pe o med unde ni ogen a mosphe e, wi h
a low o 10 mL/min.
The mog a ime ic es s we e pe o med on a TGA 500 om TA Ins umen s Inc.
(New Cas le, DE, USA). Samples we e hea ed om 25 o 800
◦
C a a hea ing a e o
10 ◦C/min unde ni ogen a mosphe e.
Fou ie - ans o med in a ed spec oscopy (FTIR) spec a we e eco ded wi h a Nicole
Nexus spec ome e om The mo Fishe Scien i ic SL (Bilbao, Spain) wi h a Golden Ga e
ATR sampling accesso y. Backg ound was eco ded be o e e e y sample and he spec a
we e ob ained in he ange o 4000–650 cm
−1
, pe o ming 32 scans wi h a esolu ion
o 4 cm−1.
The mo phologies o he cu ed BCP-DGEVA/DDM sys ems we e s udied by a omic
o ce mic oscopy (AFM) unde ambien condi ions, using a scanning p obe mic oscope
Mul imode 8 om B uke (Bille ica, MI, USA). Tapping mode (TM) was employed in ai
using an in eg a ed ip/can ile e (125 mm in leng h wi h a 300 kHz esonan equency).
Measu emen s we e pe o med wi h 512 scan lines and a ge ampli ude a ound 0.9 V.
Di e en egions o he cu ed BCP-DGEVA/DDM sys ems we e scanned o ensu e ha
he mo phology o he in es iga ed ma e ials was a ep esen a i e one. Samples we e cu
using an ul amic o ome Leica Ul acu R wi h a diamond blade.
UV- is ansmi ance spec a o he cu ed BCP-DGEVA/DDM sys ems we e pe -
o med wi h a Shimadzu UV-3600 (Kio o, Japan) spec opho ome e in he ange be ween
200 and 800 nm.
3. Resul s and Discussion
3.1. Di e en ial Scaning Calo ime y Analysis
DSC dynamic measu emen s we e ca ied ou in o de o in es iga e he miscibili y
be ween PEO-PPO-PEO iblock copolyme and DGEVA/DDM.
Figu e 1A shows he mog ams o blend componen s (PEO-PPO-PEO and DGEVA/DDM).
Mo eo e , uncu ed BCP-DGEVA/DDM blends wi h di e en BCP amoun s we e also
included in Figu e 1B. PEO-PPO-PEO he mog am shows a T
g
a a ound
−
68.5
◦
C [
32
] and
a mel ing peak cen e ed a 58.0
◦
C, ela ed o he mel ing o c ys alline PEO block. DGEVA
esin p esen s a T
g
a
−
41.7
◦
C ha inc eased up o
−
32.5
◦
C when cu ing agen was added.
This beha io can be ela ed o he pa ial miscibili y be ween he DGEVA esin and he
amine be o e cu ing. In addi ion, he DGEVA/DDM he mog am shows an exo he mic
peak cen e ed a ound 140
◦
C, indica ing he cu ing eac ion o he blend. I he dynamic
he mog ams o BCP-DGEVA/DDM sys ems a e compa ed, he T
g
o he DGEVA esin
phase dec eases om
−
36.5
◦
C o
−
44.0
◦
C wi h inc easing BCP con en , owing o he
miscibili y o PEO-PPO-PEO and DGEVA [
32
,
37
]. Mo eo e , a he he mog am o he
50BCP-DGEVA/DDM sys em, he mel ing o he c ys alline phase o he PEO block is
de ec ed and, in con as o ha o nea BCP, he mel ing happens in wo s eps, indica ing
he p esence o di e en ypes o c ys als. This phenomenon will be u he discussed in
he mo phology sec ion shown below.

Polyme s 2023,15, 1216 6 o 13
Polyme s 2023, 14, x FOR PEER REVIEW 6 o 13
c ys alline phase o he PEO block is de ec ed and, in con as o ha o nea BCP, he
mel ing happens in wo s eps, indica ing he p esence o di e en ypes o c ys als. This
phenomenon will be u he discussed in he mo phology sec ion shown below.
The cu ing beha io o all BCP-DGEVA/DDM blends was analyzed by iso he mal
he mog ams a 80, 100 and 120 °C (Figu e 2).
Figu e 1. Dynamic DSC he mog ams o (A) he nea componen s (DGEVA esin and
PEO-PPO-PEO iblock copolyme ) and uncu ed DGEVA/DDM blend, and (B) uncu ed
BCP-DGEVA/DDM blends wi h di e en BCP con en s om 10 o 50 w %. No e: he mog ams
ha e been shi ed along he Y-axes o a be e isualiza ion.
Figu e 2. Iso he mal DSC he mog ams o in es iga ed BCP-DGEVA/DDM sys ems wi h BCP
con en om 0 o 50 w % a (A) 80, (B) 100, and (C) 120 °C. No e: he mog ams ha e been shi ed
along he Y-axes o a be e isualiza ion.
As can be obse ed, he eac ion a e inc eased wi h he inc easing o cu ing em-
pe a u e, while BCP addi ion delayed he exo he mic peak o he iso he mal he mo-
g ams a all empe a u es, due o he dilu ion e ec o PEO-PPO-PEO [32,46]. Fo sys-
ems wi h highes amoun o BCP, he exo he mic peak almos disappea ed a 80 and 100
Figu e 1.
Dynamic DSC he mog ams o (
A
) he nea componen s (DGEVA esin and PEO-PPO-PEO
iblock copolyme ) and uncu ed DGEVA/DDM blend, and (
B
) uncu ed BCP-DGEVA/DDM blends
wi h di e en BCP con en s om 10 o 50 w %. No e: he mog ams ha e been shi ed along he
Y-axes o a be e isualiza ion.
The cu ing beha io o all BCP-DGEVA/DDM blends was analyzed by iso he mal
he mog ams a 80, 100 and 120 ◦C (Figu e 2).
Polyme s 2023, 14, x FOR PEER REVIEW 6 o 13
c ys alline phase o he PEO block is de ec ed and, in con as o ha o nea BCP, he
mel ing happens in wo s eps, indica ing he p esence o di e en ypes o c ys als. This
phenomenon will be u he discussed in he mo phology sec ion shown below.
The cu ing beha io o all BCP-DGEVA/DDM blends was analyzed by iso he mal
he mog ams a 80, 100 and 120 °C (Figu e 2).
Figu e 1. Dynamic DSC he mog ams o (A) he nea componen s (DGEVA esin and
PEO-PPO-PEO iblock copolyme ) and uncu ed DGEVA/DDM blend, and (B) uncu ed
BCP-DGEVA/DDM blends wi h di e en BCP con en s om 10 o 50 w %. No e: he mog ams
ha e been shi ed along he Y-axes o a be e isualiza ion.
Figu e 2. Iso he mal DSC he mog ams o in es iga ed BCP-DGEVA/DDM sys ems wi h BCP
con en om 0 o 50 w % a (A) 80, (B) 100, and (C) 120 °C. No e: he mog ams ha e been shi ed
along he Y-axes o a be e isualiza ion.
As can be obse ed, he eac ion a e inc eased wi h he inc easing o cu ing em-
pe a u e, while BCP addi ion delayed he exo he mic peak o he iso he mal he mo-
g ams a all empe a u es, due o he dilu ion e ec o PEO-PPO-PEO [32,46]. Fo sys-
ems wi h highes amoun o BCP, he exo he mic peak almos disappea ed a 80 and 100
Figu e 2.
Iso he mal DSC he mog ams o in es iga ed BCP-DGEVA/DDM sys ems wi h BCP
con en om 0 o 50 w % a (
A
) 80, (
B
) 100, and (
C
) 120
◦
C. No e: he mog ams ha e been shi ed
along he Y-axes o a be e isualiza ion.
As can be obse ed, he eac ion a e inc eased wi h he inc easing o cu ing empe -
a u e, while BCP addi ion delayed he exo he mic peak o he iso he mal he mog ams
a all empe a u es, due o he dilu ion e ec o PEO-PPO-PEO [
32
,
46
]. Fo sys ems wi h
highes amoun o BCP, he exo he mic peak almos disappea ed a 80 and 100
◦
C, as he
ull con e sion was no eached in he analyzed ime scale a 80 and 100
◦
C. Fo hese
Polyme s 2023,15, 1216 7 o 13
BCP-DGEVA/DDM sys ems, he cu ing p ocess would be comple ed a he pos -cu ing
s age. A 120
◦
C he cu ing eac ion was comple ed o all in es iga ed BCP-DGEVA/DDM
sys ems, and all composi es we e cu ed a 120 ◦C.
All BCP-DGEVA/DDM sys ems cu ed a 120
◦
C we e s udied by dynamic DSC
analysis (Figu e 3). The nea DGEVA/DDM epoxy sys em showed a T
g
a 115.1
◦
C.
Wi h PEO-PPO-PEO iblock copolyme addi ion, he T
g
o he epoxy ma ix dec eased
om 109.5
◦
C (10BCP-DGEVA/DDM sys em) o 91.6
◦
C (50BCP-DGEVA/DDM sys em),
con i ming o he epoxy ma ix he miscibili y be ween DGEVA epoxy esin and PEO block
o PEO-PPO-PEO [
26
]. Howe e , he sample wi h 30 w % o BCP p esen ed a lowe T
g
alue o o epoxy ma ix han he sample wi h 50 w % o BCP. Mo eo e , he 50BCP-
DGEVA/DDM sys em p esen ed an addi ional T
g
a
−
50.2
◦
C, which could be a ibu ed
o he T
g
o PEO block o PEO-PPO-PEO. Dynamic he mog ams o BCP-DGEVA/DDM
sys ems wi h BCP con en om 10 o 50 w % also p esen ed endo he mic peaks, ela ed
o he mel ing o PEO block o he BCP, which is ep esen ed by wo peaks ha end o
become close as he BCP con en is inc eased, indica ing di e en ypes o c ys als.
Polyme s 2023, 14, x FOR PEER REVIEW 7 o 13
°C, as he ull con e sion was no eached in he analyzed ime scale a 80 and 100 °C. Fo
hese BCP-DGEVA/DDM sys ems, he cu ing p ocess would be comple ed a he
pos -cu ing s age. A 120 °C he cu ing eac ion was comple ed o all in es iga ed
BCP-DGEVA/DDM sys ems, and all composi es we e cu ed a 120 °C.
All BCP-DGEVA/DDM sys ems cu ed a 120 °C we e s udied by dynamic DSC
analysis (Figu e 3). The nea DGEVA/DDM epoxy sys em showed a Tg a 115.1 °C. Wi h
PEO-PPO-PEO iblock copolyme addi ion, he Tg o he epoxy ma ix dec eased om
109.5 °C (10BCP-DGEVA/DDM sys em) o 91.6 °C (50BCP-DGEVA/DDM sys em), con-
i ming o he epoxy ma ix he miscibili y be ween DGEVA epoxy esin and PEO block
o PEO-PPO-PEO [26]. Howe e , he sample wi h 30 w % o BCP p esen ed a lowe Tg
alue o o epoxy ma ix han he sample wi h 50 w % o BCP. Mo eo e , he
50BCP-DGEVA/DDM sys em p esen ed an addi ional Tg a −50.2 °C, which could be a -
ibu ed o he Tg o PEO block o PEO-PPO-PEO. Dynamic he mog ams o
BCP-DGEVA/DDM sys ems wi h BCP con en om 10 o 50 w % also p esen ed endo-
he mic peaks, ela ed o he mel ing o PEO block o he BCP, which is ep esen ed by
wo peaks ha end o become close as he BCP con en is inc eased, indica ing di e en
ypes o c ys als.
Figu e 3. Dynamic DSC he mog ams o in es iga ed BCP-DGEVA/DDM sys ems wi h BCP con-
en om 0 o 50 w % cu ed a 120 °C. No e: he mog ams ha e been shi ed along he Y-axes o a
be e isualiza ion.
As has been poin ed ou by o he au ho s [26,33], he Tg o a blend depends on he
weigh ac ion o he componen s. Fo his eason, i could be expec ed ha he highe
he BCP con en in he mix u e, he lowe he Tg o he sys em will be. Howe e , in his
case, al hough he BCP amoun is highe o he 50BCP-DGEVA/DDM sys em han o
he 30BCP-DGEVA/DDM one, he alue o he Tg inc eases. This could indica e ha pa
o he PEO block phase sepa a es om he DGEVA/DDM ma ix, as ound in p e ious
wo ks o ou g oup [26]. These mel ing peaks inc eased signi ican ly in he case o he
50BCP-DGEVA/DDM sys em. The inc ease in mel ing peaks, oge he wi h he p esence
o he Tg o PEO block o BCP and he highe Tg o epoxy ma ix when compa ed wi h
ha o he 30BCP-DGEVA/DDM sys em, could indica e ha he phase sepa a ed BCP
con en could be ema kably highe in his case han o he es o he sys ems.
3.2. The mog a ime ic Analysis
The mog a ime ic analysis o PEO-PPO-PEO iblock copolyme and de eloped
BCP-DGEVA/DDM sys ems was also ca ied ou (Figu e 4). I he he mal deg ada ion
cu es o PEO-PPO-PEO and nea DGEVA/DDM a e compa ed, o bo h samples he
main deg ada ion s ep occu s be ween 350 and 425 °C. As a esul , o
BCP-DGEVA/DDM sys ems he main deg ada ion occu s in he same empe a u e ange,
showing ha BCP addi ion does no a ec he he mal s abili y o he sys em. On he
o he side, o med cha amoun (32 w % o nea epoxy sys em) p opo ionally dec eases
Figu e 3.
Dynamic DSC he mog ams o in es iga ed BCP-DGEVA/DDM sys ems wi h BCP con en
om 0 o 50 w % cu ed a 120
◦
C. No e: he mog ams ha e been shi ed along he Y-axes o a
be e isualiza ion.
As has been poin ed ou by o he au ho s [
26
,
33
], he T
g
o a blend depends on he
weigh ac ion o he componen s. Fo his eason, i could be expec ed ha he highe
he BCP con en in he mix u e, he lowe he T
g
o he sys em will be. Howe e , in his
case, al hough he BCP amoun is highe o he 50BCP-DGEVA/DDM sys em han o
he 30BCP-DGEVA/DDM one, he alue o he T
g
inc eases. This could indica e ha pa
o he PEO block phase sepa a es om he DGEVA/DDM ma ix, as ound in p e ious
wo ks o ou g oup [
26
]. These mel ing peaks inc eased signi ican ly in he case o he
50BCP-DGEVA/DDM sys em. The inc ease in mel ing peaks, oge he wi h he p esence o
he T
g
o PEO block o BCP and he highe T
g
o epoxy ma ix when compa ed wi h ha
o he 30BCP-DGEVA/DDM sys em, could indica e ha he phase sepa a ed BCP con en
could be ema kably highe in his case han o he es o he sys ems.
3.2. The mog a ime ic Analysis
The mog a ime ic analysis o PEO-PPO-PEO iblock copolyme and de eloped
BCP-DGEVA/DDM sys ems was also ca ied ou (Figu e 4). I he he mal deg ada ion
cu es o PEO-PPO-PEO and nea DGEVA/DDM a e compa ed, o bo h samples he
main deg ada ion s ep occu s be ween 350 and 425
◦
C. As a esul , o BCP-DGEVA/DDM
sys ems he main deg ada ion occu s in he same empe a u e ange, showing ha BCP
addi ion does no a ec he he mal s abili y o he sys em. On he o he side, o med cha
amoun (32 w % o nea epoxy sys em) p opo ionally dec eases wi h BCP con en om
29 w % o he 10BCP-DGEVA/DDM sys em o 14 w % o he 50BCP-DGEVA/DDM one.
Polyme s 2023,15, 1216 8 o 13
Polyme s 2023, 14, x FOR PEER REVIEW 8 o 13
wi h BCP con en om 29 w % o he 10BCP-DGEVA/DDM sys em o 14 w % o he
50BCP-DGEVA/DDM one.
Figu e 4. TGA cu es o PEO-PPO-PEO block copolyme and BCP-DGEVA/DDM sys ems wi h
BCP con en om 0 o 50 w % cu ed a 120 °C.
3.3. Fou ie -T ans o m In a ed Spec oscopy Analysis
Figu e 5A shows FTIR spec a o DGEVA esin and he DGEVA/DDM sys em. I
hese wo spec a a e compa ed, in he case o DGEVA/DDM sys em, a b oad band cen-
e ed a 3370 cm−1 is de ec ed, a ibu ed o he alcohol g oups o med a e he eac ion o
he epoxy g oups o DGEVA and he amine g oups o DDM [33]. In addi ion, he peak
ela ed o he epoxide g oup (910 cm−1) disappea s a he cu ed spec um, p o ing he
cu ing o he epoxy esin [33,55].
Figu e 5. FTIR spec a o (A) nea DGEVA esin and DGEVA/DDM sys em, and (B) in es iga ed
BCP-DGEVA/DDM sys ems wi h BCP con en om 0 o 50 w % cu ed a 120 °C. No e: spec a ha e
been shi ed along he Y-axes o a be e isualiza ion.
Rega ding he e ec o PEO-PPO-PEO iblock copolyme addi ion, Figu e 5B shows
ha by inc easing BCP con en , he in ensi y o he band ela ed o alcohol g oups (b oad
band cen e ed a 3370 cm−1, in DGEVA/DDM) dec eases and shi s owa ds highe
wa enumbe s (3387 and 3428 cm−1 o 15BCP-DGEVA/DDM and 50BCP-DGEVA/DDM,
espec i ely). This could be due o he hyd ogen bonding in e ac ion be ween he OH
g oups o med in he cu ed esin and he PEO block o he iblock copolyme [33].
Mo eo e , in he spec a o sys ems wi h highe BCP con en (30 and 50 w %) he bands
ela ed o he PEO-PPO-PEO block copolyme p esen highe in ensi y.
Figu e 4.
TGA cu es o PEO-PPO-PEO block copolyme and BCP-DGEVA/DDM sys ems wi h BCP
con en om 0 o 50 w % cu ed a 120 ◦C.
3.3. Fou ie -T ans o m In a ed Spec oscopy Analysis
Figu e 5A shows FTIR spec a o DGEVA esin and he DGEVA/DDM sys em. I hese
wo spec a a e compa ed, in he case o DGEVA/DDM sys em, a b oad band cen e ed
a 3370 cm
−1
is de ec ed, a ibu ed o he alcohol g oups o med a e he eac ion o he
epoxy g oups o DGEVA and he amine g oups o DDM [
33
]. In addi ion, he peak ela ed
o he epoxide g oup (910 cm
−1
) disappea s a he cu ed spec um, p o ing he cu ing o
he epoxy esin [33,55].
Polyme s 2023, 14, x FOR PEER REVIEW 8 o 13
wi h BCP con en om 29 w % o he 10BCP-DGEVA/DDM sys em o 14 w % o he
50BCP-DGEVA/DDM one.
Figu e 4. TGA cu es o PEO-PPO-PEO block copolyme and BCP-DGEVA/DDM sys ems wi h
BCP con en om 0 o 50 w % cu ed a 120 °C.
3.3. Fou ie -T ans o m In a ed Spec oscopy Analysis
Figu e 5A shows FTIR spec a o DGEVA esin and he DGEVA/DDM sys em. I
hese wo spec a a e compa ed, in he case o DGEVA/DDM sys em, a b oad band cen-
e ed a 3370 cm−1 is de ec ed, a ibu ed o he alcohol g oups o med a e he eac ion o
he epoxy g oups o DGEVA and he amine g oups o DDM [33]. In addi ion, he peak
ela ed o he epoxide g oup (910 cm−1) disappea s a he cu ed spec um, p o ing he
cu ing o he epoxy esin [33,55].
Figu e 5. FTIR spec a o (A) nea DGEVA esin and DGEVA/DDM sys em, and (B) in es iga ed
BCP-DGEVA/DDM sys ems wi h BCP con en om 0 o 50 w % cu ed a 120 °C. No e: spec a ha e
been shi ed along he Y-axes o a be e isualiza ion.
Rega ding he e ec o PEO-PPO-PEO iblock copolyme addi ion, Figu e 5B shows
ha by inc easing BCP con en , he in ensi y o he band ela ed o alcohol g oups (b oad
band cen e ed a 3370 cm−1, in DGEVA/DDM) dec eases and shi s owa ds highe
wa enumbe s (3387 and 3428 cm−1 o 15BCP-DGEVA/DDM and 50BCP-DGEVA/DDM,
espec i ely). This could be due o he hyd ogen bonding in e ac ion be ween he OH
g oups o med in he cu ed esin and he PEO block o he iblock copolyme [33].
Mo eo e , in he spec a o sys ems wi h highe BCP con en (30 and 50 w %) he bands
ela ed o he PEO-PPO-PEO block copolyme p esen highe in ensi y.
Figu e 5.
FTIR spec a o (
A
) nea DGEVA esin and DGEVA/DDM sys em, and (
B
) in es iga ed
BCP-DGEVA/DDM sys ems wi h BCP con en om 0 o 50 w % cu ed a 120
◦
C. No e: spec a ha e
been shi ed along he Y-axes o a be e isualiza ion.
Rega ding he e ec o PEO-PPO-PEO iblock copolyme addi ion, Figu e 5B shows
ha by inc easing BCP con en , he in ensi y o he band ela ed o alcohol g oups (b oad
band cen e ed a 3370 cm
−1
, in DGEVA/DDM) dec eases and shi s owa ds highe
wa enumbe s (3387 and 3428 cm
−1
o 15BCP-DGEVA/DDM and 50BCP-DGEVA/DDM,
espec i ely). This could be due o he hyd ogen bonding in e ac ion be ween he OH
g oups o med in he cu ed esin and he PEO block o he iblock copolyme [
33
]. Mo e-
o e , in he spec a o sys ems wi h highe BCP con en (30 and 50 w %) he bands ela ed
o he PEO-PPO-PEO block copolyme p esen highe in ensi y.
3.4. A omic Fo ce Mic oscopy
The mo phologies o he BCP-DGEVA/DDM sys ems cu ed a 120
◦
C we e in es i-
ga ed by AFM. As can be obse ed in Figu e 6, all in es iga ed sys ems show mic ophase
sepa a ion a nanoscale. In he case o he samples wi h BCP con en up o 30 w %, i is
Polyme s 2023,15, 1216 9 o 13
ema kable he o ma ion o small nanos uc u es. Fo he sys em wi h 10 w % o block
copolyme (Figu e 6A), a hexagonally packed cylinde mo phology is o med, in which
he da k sphe ical domains wi h diame e s anging om 10 o 15 nm co espond o he
PPO block ich phase, while he con inuous ligh phase co esponds o he PEO-epoxy ich
one [
31
]. As o he au ho s ha e epo ed o DGEBA epoxy sys ems [
26
,
37
,
46
], i seems
ha as a esul o he in e ac ions be ween he PEO block and epoxy esin, he PEO block
is miscible wi h DGEBA epoxy esin, while PPO emains immiscible. In he case o he
sys em based on DGEVA esin, a simila beha io is obse ed. As shown in Figu e 6B,
an inc ease o 5 w % in PEO-PPO-PEO iblock copolyme con en seems no o a ec he
mo phology obse ed, as he 15BCP-DGEVA/DDM sys em p esen s he same mo phology
han he 10BCP-DGEVA/DDM one. Mo eo e , o he 30BCP-DGEVA/DDM sys em, no
signi ican mo phological changes a e de ec ed, obse ing a simila hexagonally packed
cylinde mo phology (ma ked a he images) han o 10BCP-DGEVA/DDM and 15BCP-
DGEVA/DDM sys ems. On he con a y, when PEO-PPO-PEO concen a ion ises up o
50 w %, he mo phology changes d as ically. In his case, la ge wo m-like domains (PPO
block) a e obse ed, su ounded by wo di e en phases, one o hem ich in PEO (lowe
ha dness) and he las phase ich in cu ed DGEVA [
56
]. This ac could be in ag eemen
wi h he dynamic DSC esul s o he 50BCP-DGEVA/DDM sys em shown in Figu e 3, in
which an addi ional Tga ibu ed o he PEO block o PEO-PPO-PEO was de ec ed.
Polyme s 2023, 14, x FOR PEER REVIEW 9 o 13
3.4. A omic Fo ce Mic oscopy
The mo phologies o he BCP-DGEVA/DDM sys ems cu ed a 120 °C we e in es i-
ga ed by AFM. As can be obse ed in Figu e 6, all in es iga ed sys ems show mic ophase
sepa a ion a nanoscale. In he case o he samples wi h BCP con en up o 30 w %, i is
ema kable he o ma ion o small nanos uc u es. Fo he sys em wi h 10 w % o block
copolyme (Figu e 6A), a hexagonally packed cylinde mo phology is o med, in which
he da k sphe ical domains wi h diame e s anging om 10 o 15 nm co espond o he
PPO block ich phase, while he con inuous ligh phase co esponds o he PEO-epoxy
ich one [31]. As o he au ho s ha e epo ed o DGEBA epoxy sys ems [26,37,46], i
seems ha as a esul o he in e ac ions be ween he PEO block and epoxy esin, he PEO
block is miscible wi h DGEBA epoxy esin, while PPO emains immiscible. In he case o
he sys em based on DGEVA esin, a simila beha io is obse ed. As shown in Figu e
6B, an inc ease o 5 w % in PEO-PPO-PEO iblock copolyme con en seems no o a ec
he mo phology obse ed, as he 15BCP-DGEVA/DDM sys em p esen s he same mo -
phology han he 10BCP-DGEVA/DDM one. Mo eo e , o he 30BCP-DGEVA/DDM
sys em, no signi ican mo phological changes a e de ec ed, obse ing a simila hexago-
nally packed cylinde mo phology (ma ked a he images) han o 10BCP-DGEVA/DDM
and 15BCP-DGEVA/DDM sys ems. On he con a y, when PEO-PPO-PEO concen a ion
ises up o 50 w %, he mo phology changes d as ically. In his case, la ge wo m-like
domains (PPO block) a e obse ed, su ounded by wo di e en phases, one o hem ich
in PEO (lowe ha dness) and he las phase ich in cu ed DGEVA [56]. This ac could be
in ag eemen wi h he dynamic DSC esul s o he 50BCP-DGEVA/DDM sys em shown
in Figu e 3, in which an addi ional Tg a ibu ed o he PEO block o PEO-PPO-PEO was
de ec ed.
Figu e 6. AFM phase images o BCP-DGEVA/DDMP sys ems cu ed a 120 °C wi h (A) 10 w %, (B)
15 w %, (C) 30 w %, and (D) 50 w % o PEO-PPO-PEO.
Figu e 6.
AFM phase images o BCP-DGEVA/DDMP sys ems cu ed a 120
◦
C wi h (
A
) 10 w %,
(B) 15 w %, (C) 30 w %, and (D) 50 w % o PEO-PPO-PEO.
3.5. UV-Vis Spec oscopy
UV- is ansmi ance esul s o he BCP-DGEVA/DDM sys ems wi h di e en PEO-
PPO-PEO con en s a e shown in Figu e 7. The ansmi ance o he DGEVA/DDM sys em
dec eases wi h he addi ion o iblock copolyme . The DGEVA/DDM sys em p esen s a
ansmi ance alue o 77% a 650 nm, while alues o 75, 74 and 73% a e measu ed o