Reac i e and Func ional Polyme s 196 (2024) 105842
A ailable online 1 Feb ua y 2024
1381-5148/© 2024 The Au ho (s). Published by Else ie B.V. This is an open access a icle unde he CC BY-NC-ND license (h p://c ea i ecommons.o g/licenses/by-
nc-nd/4.0/).
He e o- unc ionaliza ion o polyi acona es o de eloping imp o ed
polyme dielec ics: Me ging sul ones wi h bulky/ igid cycles
Sebas ian Bona dd
a
,
b
,
*
, Jon Maiz
a
,
c
, Angel Aleg ía
a
,
b
, Jos´
e A. Pomposo
a
,
b
,
c
,
Es e Ve de Ses o
a
,
c
, Galde Ko abe ia
d
, Da id Díaz Díaz
e
,
a
Cen o de Física de Ma e iales (CSIC, UPV/EHU) and Ma e ials Physics Cen e MPC, Paseo Manuel de La diz´
abal 5, E-20018 Donos ia, Spain
b
Depa amen o de Políme os y Ma e iales A anzados: Física, Química y Tecnología, Uni e si y o he Basque Coun y (UPV/EHU), Paseo Manuel de La diz´
abal 3, E-
20018 Donos ia, Spain
c
IKERBASQUE – Basque Founda ion o Science, Plaza de Euskadi 5, 48009 Bilbao, Spain
d
Ma e ials +Technologies" G oup, Chemical and En i onmen al Enginee ing Depa men , UPV/EHU, Plaza Eu opa 1, 20018 Donos ia, Spain
e
Depa amen o de Química O g´
anica, Uni e sidad de La Laguna, A da. As o ísico F ancisco S´
anchez 3, La Laguna 38206, Tene i e, Spain
Ins i u o Uni e si a io de Bio-O g´
anica An onio Gonz´
alez, Uni e sidad de La Laguna, A da. As o ísico F ancisco S´
anchez 2, La Laguna 38206, Tene i e, Spain
ARTICLE INFO
Keywo ds:
Polyme dielec ics
Dipola glass polyme s
Polyi acona es
Ene gy s o age
ABSTRACT
This wo k add esses he p epa a ion o new polyme dielec ics wo king unde he dipola glass polyme (DGP)
concep . He ein, we epo he syn hesis and cha ac e iza ion o ou he e o- unc ionalized polyi acona es
bea ing sul ones as high dipole momen en i ies and no bo nane o adaman ane s uc u es esponsible o
inc easing he glass ansi ion empe a u e (T
g
) and hus he ange o empe a u es whe e hey can wo k wi hou
deg ading o showing high ene gy dissipa ion. As a esul , all ob ained polyme s exhibi ed dielec ic cons an s
(
ε
’) be ween 5.1 and 6.2 while p esen ing low loss ac o s (Tan(δ) <0.01), eaching he s a us o high-dielec ic
polyme s wi h a low dissipa i e beha io . In addi ion, i was demons a ed ha including bulky s uc u es in o
hei polyme backbone allows o an inc ease o up o 80 ◦C in hei wo king empe a u e anges, expanding he
empe a u e ange whe e hey beha e as DGPs in an ou s anding manne . A comple e s uc u al, he mal and
dielec ic cha ac e iza ion was ca ied ou in e ms o in a ed spec oscopy (FTIR), nuclea magne ic esonance
(NMR), he mog a ime y (TGA), di e en ial scanning calo ime y (DSC) and b oad dielec ic spec oscopy
(BDS). O e all, hese ma e ials seem o ul ill he basic equi emen s o be conside ed good candida es o
dielec ic applica ions such as ene gy s o age, con i ming he e sa ili y o polyi acona e-based ma e ials.
1. In oduc ion
In he las decade, all-polyme dielec ics ha e ga ne ed inc easing
a en ion om he scien i ic communi y, esul ing in an ab up inc ease
esea ch in e es [1–8]. As a consequence, he amoun and di e si y o
new polyme ma e ials wi h enhanced dielec ic p ope ies ha e shown
a ema kable inc ease. This allows no only he de elopmen o new
ma e ials bu also en iches ou unde s anding o he opic om a
heo e ical pe spec i e, which, in any case, ein o ces he o me
[9–11]. A guably, he sudden in e es in he ield can be a ibu ed o he
ene gy si ua ion ou cu en socie y is acing. Wi hou changing ou
consump ion habi s and he sou ces om which we ob ain ene gy, an
upcoming ene gy sho age is ine i able [12]. The e o e, i is impe a i e
o g asp ha he de elopmen o e icien and sus ainable ene gy
acquisi ion p ocesses om clean and enewable sou ces would be in ain
i , once ob ained, we a e unable o u ilize i e ec i ely. To ensu e his,
one app oach in ol es c ea ing and/o ein o cing echnologies ha
ocus on e icien s o age, con e sion and dis ibu ion o ob ained en-
e gy. This is whe e polyme dielec ics eme ge as a ac i e candida es
o achie e and p omo e a mo e e icien and e ec i e ene gy s o age
p ocess, pa icula ly h ough he ab ica ion o imp o ed capaci o de-
ices [6,13–15].
A capaci o allows ene gy s o age in he o m o elec os a ic ene gy
ha , subsequen ly, can be eleased as elec ical discha ge. These de ices
ind applica ion in a wide spec um o a eas anging om i ial elec-
ical ci cui s (such as household appliances and de ib illa o s, among
* Co esponding au ho a : Cen o de Física de Ma e iales (CSIC, UPV/EHU) and Ma e ials Physics Cen e MPC, Paseo Manuel de La diz´
abal 5, E-20018 Donos ia,
Spain.
E-mail add ess: [email p o ec ed] (S. Bona dd).
Con en s lis s a ailable a ScienceDi ec
Reac i e and Func ional Polyme s
jou nal homepage: www.else ie .com/loca e/ eac
h ps://doi.o g/10.1016/j. eac unc polym.2024.105842
Recei ed 20 No embe 2023; Recei ed in e ised o m 25 Janua y 2024; Accep ed 26 Janua y 2024
Reac i e and Func ional Polyme s 196 (2024) 105842
2
o he s) o o he mo e complex and ad anced ones such as powe pulse
applica ions, hyb id/elec ic ehicles, ae ospace echnology, obo ics,
(bio)senso s, ec i ie s and accumula o s in wind and sola a ms
[3,6,16]. The hea o a capaci o is, p ecisely, he dielec ic ma e ial,
which is in ima ely ela ed o he amoun o cha ge (ene gy) ha he
de ice is able o s o e. The e o e, physics has augh us ha he
maximum ene gy s o ed ha a capaci o could sus ain ollows he
ela ion U
e
=½(
ε
’E
b
2
), whe e
ε
’ and E
b
ep esen he dielec ic cons an
and dielec ic b eakdown, espec i ely [3]. Bo h pa ame e s a e di ec ly
ela ed o he dielec ic ma e ial placed in he capaci o , e idencing he
need o employ ma e ials wi h he highes possible
ε
’ and E
b
alues.
Rega ding he abo e, using polyme s as dielec ics p esen s ad an ages
and disad an ages when compa ed, o example, o ino ganic sys ems.
Among he ad an ages, p obably he mos ele an , is ha polyme s
o e no ably highe E
b
alues as dielec ic media, in addi ion o hei
be e mechanical p ope ies, ligh weigh , easy p ocessabili y and
manu ac u e, syn he ic e sa ili y and low-cos p oduc ion. Howe e ,
hey lack high
ε
’ alues, usually alling wi hin he ange o 2–4 [3,17].
Un o una ely, E
b
– which is he one con ibu ing mo e om a ma he-
ma ical poin o iew – has shown a igh e ela ionship wi h he
inhe en na u e o he ma e ial, making i di icul o modi y while on
he con a y,
ε
’ has been shown o be mo e unable by manipula ing he
chemis y o he ma e ial. Taking in o accoun he abo e, i has been
demons a ed ha by endowing a ma e ial wi h a g ea e pola iza ion
abili y, i s
ε
’ can be augmen ed ou s andingly [18,19]. The e o e,
sea ching o new s a egies o a o d he p epa a ion o polyme s wi h
ε
’ abo e con en ional alues bu also p esen ing a low dissipa i e
beha io has become a demanded and ui ul esea ch ield.
Rega ding he la e , o da e, one o he mos e ec i e and p omising
s a egies o de eloping new polyme dielec ics wi h high
ε
’ and low
dissipa ion beha io is he manu ac u e o dipola glass polyme s (DGPs).
This concep , in oduced by Lei Zhu [17] almos en yea s ago, is
e e ed o as polyme ic ma e ials ul illing wo main equi emen s: 1) o
con ain small-sized high dipole momen unc ional g oups co alen ly
a ached o i s s uc u e and 2) o be an amo phous ma e ial wi h a glass
ansi ion empe a u e (T
g
) as high as possible [20]. The e o e, he po-
la iza ion mechanism h ough which DGPs base hei dielec ic p op-
e ies is mainly go e ned by he o ien a ional mo ions ha hese dipola
en i ies can pe o m wi hin he amo phous ma ix when exposed o an
ex e nal elec ic ield. In his con ex , he need o an amo phous
s uc u e is d i en by he inhe en ee olume p esen in hese ma e-
ials. This, combined wi h he equi emen o small-sized dipole
momen unc ional g oups, c ea es an en i onmen conduci e o un-
hinde ed o ien a ional mo ions. Equally c ucial is he demand o a high
T
g
, ensu ing he ma e ial’s esilience unde he ypically hea ed condi-
ions expe ienced by dielec ic ma e ials.
A high T
g
alue se es a dual pu pose. Fi s , i p e en s he ma e ial
om en e ing a ubbe y s a e ha could lead o leakage and subsequen
ailu e. Second, i delays he onse o dissipa i e phenomena on he
empe a u e scale, di ec ly in luencing he ene gy s o age capaci y o
he sys em. Among a ious dissipa i e phenomena, he ise in ionic
conduc i i y nea T
g
is pa icula ly de imen al, as i impac s he insu-
la ion p ope y o he dielec ic ma e ial [18,20,21]. This is a conse-
quence o di usion p ocesses acili a ed by ionic impu i ies, which a e
inhe en ly p esen in hese polyme ic ma e ials and become ac i a ed as
he polyme chains unde go long segmen al mo ions, ypically occu ing
when he ma e ial app oaches i s ubbe y s a e. When a DGP su passes
i s T
g
, i ansi ions in o a pa aelec ic s a e cha ac e ized by highe po-
la iza ion bu also a highly dissipa i e beha io . Ideally, in a DGP, one
seeks a ma e ial wi h dipola s uc u es capable o o ien a ional mo ions
om he lowes possible empe a u e while also possessing he highes
a ainable T
g
alue. This would esul in a ma e ial exhibi ing a wide
empe a u e ange wi h a highly pola ized s a e, de oid o signi ican
dissipa i e p ocesses. This empe a u e ange, o en e e ed o as he
DGP’s `swee spo ´, ep esen s he egime whe e he pa aelec ic s a e
domina es [22].
The la ge numbe o epo s wi hin he las i e yea s demons a es
he success o DGPs as a s a egy o he p epa a ion o new all-polyme
dielec ics wi h high
ε
’ alues (>4) [8,23–26]. In his sense, di e se
polyme s uc u es anging om a oma ic o alipha ic and om syn-
he ic o bio-based sys ems ha e been designed and p epa ed o con ain
highly dipola unc ionali ies and achie e supe io dielec ic p ope ies
[4,26–32]. Among hese unc ionali ies, ni iles and sul ones ha e been
he ones ha ha e a ac ed he mos a en ion due o hei high dipole
momen s (3.9 and 4.25 Debye, espec i ely) and easy inco po a ion
[17]. Howe e , in 2015, Wei e al. se an unp eceden ed esul in he
ield o DGPs, whe e a new sul onyl-con aining polyme hac yla e ach-
ie ed an
ε
’ alue o 11.2 and a loss ac o – Tan(δ) – o 0.02 a oom
empe a u e [20]. Since hen, sul ones ha e aken he lead as dipola
en i ies o excellence in de eloping new polyme ma e ials wi h
imp o ed dielec ic p ope ies, as can be e i ied in he ollowing e -
e ences o name a ew [22,33–41]. O cou se, i is e iden ha one o he
pa hs o ollow in seeking new and imp o ed DGPs is he design and
es ing o new polyme s uc u es deco a ed wi h hese molecula di-
poles. In his con ex , and o una ely, some o us we e able o con ibu e
o his ield by in oducing, o he i s ime, polyi acona es as dielec ic
media [34,42,43]. One o he main a ac i eness o hese polyme s is
he double unc ionali y o hei monome ic uni s – de i ed om i a-
conic acid – ha pe mi s playing no only wi h he ype o subs i uen
bu also wi h he numbe , in his case, o dipoles. Thus, in a se ies o
consecu i e wo ks, we ha e success ully p o en ha hese ma e ials can
ac as aluable dielec ic media by exhibi ing high
ε
’ alues ( om 4 o
16) while p esen ing low Tan(δ) alues (<0.02) a e he chemical
inco po a ion o ni iles and sul onyl g oups. Mo e impo an ly, we ha e
also demons a ed ha he inco po a ion o bulky pendan g oups in o
dipole-con aining polyi acona es u ned ou o be a sui able s a egy o
d ama ically inc ease he T
g
o hese sys ems and, consequen ly, he
empe a u e ange whe e hese beha e as DGPs.
Thus, wi h he aim o con inuing o explo e he pe o mance o
polyi acona es as dielec ic media, his wo k p esen s a no el app oach
o achie e an imp o ed e sion o ou p e ious epo dealing wi h he
use o dipola polyi acona es bea ing bulky subs i uen s [43]. In ha
oppo uni y, we success ully p epa ed o h ee new polyi acona es
he e o- unc ionalized ha had, on he one hand, no bo nane o ada-
man ane pendan g oups and, on he o he hand, ni iles as dipola
en i ies. E en when hese ma e ials exhibi ed no ably high T
g
s, b oad
DGP empe a u e anges and, he e o e, low dissipa i e beha io (Tan
<0.01), hei
ε
’ alues – be ween 4.0 and 4.3 – ba ely su passed he
uppe limi es ablished o con en ional polyme s. The e o e, o each
highe
ε
’ alues and inspi ed by he supe io pe o mance shown by
sul onyl-con aining polyme s, in his wo k we ca ied ou o he i s
ime he eplacemen o ni iles by sul one uni s in ou new poly-
i acona es ha ing no bo nane and adaman ane de i a i es as seconda y
pendan g oups. These ma e ials we e success ully p epa ed h ough he
polyme iza ion o hei espec i e monome ic uni s and cha ac e ized in
e ms o hei s uc u al, he mal, and dielec ic p ope ies.
2. Expe imen al sec ion
2.1. Ma e ials
I aconic acid (≥99%, CAS 97–65-4), ace yl chlo ide (≥99%, CAS
75–36-5), Exo-no bo neol (98%, CAS 497–37-0), 2-No bo naneme ha-
nol (mix u e o endo and exo, 97%, CAS 5240-72-2), 1-Ada-
man aneme hanol (99%, CAS 770–71-8), 1-Adaman anol (99%, CAS
768–95-6), N,N
′
-dicyclohexylca bodiimide (DCC, 98%, CAS 538–75-0),
and 4-(dime hylamino)py idine (DMAP, ≥99%, CAS 1122-58-3) we e
all pu chased om Sigma–Ald ich. 2-(Me hylsul onyl)e hanol (98%,
CAS 15205–66-0) was acqui ed om Fluo ochem. 2,2
′
-Azobis(2-me h-
ylp opioni ile) (AIBN, 98%, CAS 78–67-1) was pu chased om Fluka.
All sol en s used in his wo k we e pu chased om Me ck and used
wi hou u he pu i ica ion unless s a ed.
S. Bona dd e al.
Reac i e and Func ional Polyme s 196 (2024) 105842
3
2.2. Cha ac e iza ion echniques
1
H NMR and
13
C NMR spec a we e eco ded on a B uke A ance II-
500 sys em using CDCl
3
and DMSO‑d
6
as sol en s o monome s and
polyme s, espec i ely. FTIR spec a o specimens we e eco ded in a
Ca y 630 FTIR spec opho ome e (Agilen ) equipped wi h an ATR
accesso y be ween 650 and 4000 cm
−1
a e 34 scans in ansmission
mode and wi h a esolu ion o 2 cm
−1
. The molecula weigh o polyme s
was de e mined by size-exclusion ch oma og aphy (SEC) using a Shi-
madzu Nexe a 40 HPLC sys em, equipped wi h a pola gel-M gua d (50
×7.5 mm) and a pola gel-M column (300 ×7.5 mm), bo h om Agilen .
A di e en ial e ac i e index (dRI) de ec o (RID-20 A, Shimadzu) was
used as a de ec ion sys em. A solu ion o LiB in N,N-dime hyl o mamide
(DMF) (0.1 w %) was used as he eluen (1 mL/min low a e), and
polys y ene (PS) s anda ds we e employed o con en ional calib a ion.
The densi y alues o he polyme ilms we e calcula ed using a op-
loading elec onic METTLER balance (ME-33360) and me hanol (den-
si y 0.792 g/cm
3
a oom empe a u e).
The he mal cha ac e iza ion o samples was ca ied ou using a
simul aneous he mal analyze (TG/DSC) Disco e y SDT 650 (TA In-
s umen s) and a di e en ial scanning calo ime e Disco e y DSC 025
(TA Ins umen s). The mog a ime ic analysis (TGA) was pe o med
be ween 25 ◦C and 800 ◦C a 10 ◦C/min unde a ni ogen a mosphe e.
F om he ob ained he mog ams, he deg ada ion onse empe a u e
(T
i
), maximum weigh loss a e empe a u e (T
MD
) and esidue pe -
cen age (R) we e calcula ed. T
i
is de ined as he empe a u e a which
he ma e ial loses 5% o i s ini ial weigh . On he o he hand, di e en ial
scanning calo ime y (DSC) analysis in ol ed he ollowing i e
consecu i e s eps: i) dynamic hea ing om 25 ◦C o 200 ◦C a 20◦/min,
ii) iso he mal p ocess a 200 ◦C o 3 min, iii) dynamic cooling p ocess
going om 200 ◦C o 0 ◦C a 20 ◦C/min, i ) iso he mal p ocess a 0 ◦C o
3 min, and inally, ) a dynamic hea ing p ocess om 0 ◦C o 200 ◦C a
10◦/min. The in o med glass ansi ion empe a u es (T
g
) we e calcu-
la ed om he in lec ion poin de ec ed in he mog ams acqui ed om
he las hea ing s ep.
B oadband dielec ic spec oscopy was used o pe o m he dielec ic
cha ac e iza ion o he ma e ials. Measu emen s we e ca ied ou using
a No ocon ol Alpha high- esolu ion analyze wi h an applied AC
ol age o 1.0 V, om which equency scans (iso he mal spec a) and
empe a u e scans (isoch onal spec a) we e ob ained. F equency scans
we e measu ed in he ange be ween 10
−1
and 10
6
Hz. These mea-
su emen s we e aken a di e en empe a u es anging om – 150 ◦C o
25 ◦C. On he o he hand, isoch onal spec a we e eco ded om –
150 ◦C o 150 ◦C a equencies be ween 1 and 10
6
Hz. The sample
p epa a ion o dielec ic measu emen s is ou lined below. Fi s , a
ce ain amoun o polyme powde is ho -p essed be ween wo me al
discs a a empe a u e T
g
+30 ◦C and 2 ons o p essu e, achie ing he
o ma ion o a bubble- ee ilm. La e , his ilm was ho -p essed again
be ween wo gold-pla ed elec odes o di e en diame e s (20 mm and
30 mm), using he elec ode wi h he g ea e diame e as he bo om pa
in he sandwich con igu a ion. Ini ially, he hickness o he ilm was
de e mined as he di e ence in hickness be ween bo h elec odes
be o e and a e ho p essing he polyme ilm. Howe e , he abo e
alue was co ec ed by measu ing he hickness o he peeled-o ilm
om he elec odes a e he dielec ic measu emen s. I is wo h
men ioning ha samples placed be ween elec odes we e d ied o e -
nigh unde acuum a 130 ◦C and hen s o ed in a desicca o be o e
analysis. Rela i e pe mi i i y alues (ԑ
’) we e calcula ed using eq. 1:
ԑ
′
=C’
Pd
ԑO
π
2(1)
whe e ԑ
’ is he calcula ed dielec ic cons an , C
p
’ is he eal pa o he
measu ed capaci ance in he pa allel con igu a ion, d is he hickness o
he polyme ilm, ԑ
o is
he acuum pe mi i i y (8.85 ×10
−12
F m
−1
) and
is he adius o he op elec ode. Once calcula ed ԑ
’, he dielec ic loss
(ԑ
”) pa ame e was calcula ed using he ela ion ԑ
” =ԑ
’ Tan(δ), whe e
Tan(δ) is he loss ac o ob ained di ec ly om he expe imen al
measu emen s.
A Me icon model 2010 p ism couple was used o de e mine he
e ac ion index (n) o he polyme ilms a e dielec ic measu emen s.
Values o 1.5285, 1.5292, 1.5298, and 1.5304 we e ob ained o
PSO
2
mNORI, PSO
2
NORI, PSO
2
mADAI and PSO
2
ADAI, espec i ely.
2.3. Monome syn hesis
The spec oscopic da a (FTIR,
1
H and
13
C NMR) belonging o i aconic
anhyd ide, he ob ained monome s and hei espec i e in e media es
can be consul ed in he suppo ing in o ma ion ile.
2.3.1. I aconic anhyd ide
In a wo-neck ound bo om glass, 10 g (7.7 mmol) o i aconic acid
and 19 mL (26.3 mmol) o ace yl chlo ide we e added and s i ed a
55 ◦C o 2.5 h. Then, 10 mL o d y oluene was added o he eac ion and
e luxed o 3 h using a Dean-S a k appa a us. Subsequen ly, 25 mL o
die hyl e he was added, and he solu ion was s o ed a −20 ◦C o e -
nigh . The esul ing whi e c ys als we e washed wi h cold die hyl e he
and d ied in a acuum o en un il cons an weigh . Yield: 81%. Mel ing
poin : 65–68 ◦C.
2.3.2. P epa a ion o mono me hylno bo nyl i aconic acid (1a), mono
no bo nyl i aconic acid (1b), mono me hyladaman yl i aconic acid (1c) and
mono adaman yl i aconic acid (1d)
The syn hesis o mono-es e i aconic acids 1a, 1b and 1c was ach-
ie ed ollowing a sligh ly modi ied p o ocol p e iously epo ed by ou
g oup, which was also use ul o he p epa a ion, o he i s ime, o
specimen 1d [43]. B ie ly, in a wo-neck ound bo om lask coupled o a
e lux sys em, 2.00 g (18 mmol) o i aconic anhyd ide was mixed wi h
1.2 equi alen s (21 mmol) o he co esponding alcohol and solubilized
in 15 mL o d y oluene. The eac ion was hea ed a 120 ◦C o 24 h, a e
which he sol en was emo ed in a o a y e apo a o a educed
p essu e, ob aining a anspa en oil in all cases. 1a and 1b we e suc-
cess ully pu i ied by c ys alliza ion, pou ing he anspa en oil in o 10
mL o hexane and s o ing hem o 24 h a −20 ◦C, allowing he o -
ma ion o whi e c ys als. In he case o 1c and 1d, he pu i ica ion
p ocess was ca ied ou by column ch oma og aphy using a mix u e o
hexane:ace one (7:3) as he eluen , o gi e a anspa en oil ha solid-
i ies in he o m o whi e c ys als upon cooling a −20 ◦C. Samples 1a,
1b, 1c and 1d we e ob ained wi h yields o 68, 81, 55 and 57%,
espec i ely.
2.3.3. P epa a ion o 2-(me hylsul onyl)e hyl me hylno bo nyl i acona e
(2a), 2-me hylsul onyle hyl no bo nyl i acona e (2b), 2-me hylsul onyle hyl
me hyladaman yl i acona e (2c) and 2-me hylsul onyle hyl adaman yl
i acona e (2d)
The syn hesis o dii acona es 2a, 2b, 2c and 2d was pe o med
s a ing om hei co esponding mono i acona e es e s 1a, 1b, 1c and
1d, ollowing he same expe imen al p o ocol in each case. The p o ocol
is desc ibed below, using he syn hesis o 2a as an example:
A o al o 3.0 g o 1a (13.0 mmol) and 2.4 g o 2-(me hylsul onyl)
e hanol (19.5 mmol, 1.5 equi ) we e solubilized in 30 mL o d y
dichlo ome hane (DCM) and cooled in an ice-wa e ba h. Simul a-
neously, a second solu ion was p epa ed in a ound-bo om glass by
dissol ing 3.2 g o DCC (15.6 mmol, 1.2 equi ) and 0.3 g o DMAP (2.6
mmol, 0.2 equi ) in 70 mL o d y DCM, which was le unde cons an
s i ing in an ice-wa e ba h. A e wa ds, when bo h solu ions eached
0 ◦C, he i s solu ion was added d opwise o e he second solu ion
unde cons an s i ing, and a e concluding he addi ion, he eac ion
mix u e was allowed o each oom empe a u e and eac o 24 h,
main aining he s i ing condi ions. Then, he mix u e was s o ed
o e nigh a −20 ◦C o a o he p ecipi a ion o he dicyclohexyl u ea
(DCU) subp oduc . The cooled mix u e was il e ed and subjec ed o
S. Bona dd e al.
Reac i e and Func ional Polyme s 196 (2024) 105842
4
consecu i e washing s eps wi h b ine (5 ×50 mL), a e which he
o ganic phase was d ied o e anhyd ous MgSO
4
and il e ed. The sol-
en s we e emo ed unde educed p essu e, and he whi ish oil ob-
ained (wi h clea p esence o DCU aces) was success ully pu i ied by
column ch oma og aphy (7:3, e hyl ace a e:hexane), a o ding a ans-
pa en oil ha slowly o med a whi e solid o e ime (2a). Yield =71%.
Simila ly, a e column ch oma og aphy, 2b, 2c and 2d u ned ou o
be anspa en oils ha , a e a ce ain pe iod o ime, became whi e
solids. The calcula ed yields o 2b, 2c and 2d we e 68, 61 and 78%,
espec i ely.
2.4. Syn hesis o polyi acona es
The syn hesis o polyme s was ca ied ou in bulk using AIBN as he
adical ini ia o . Typically, 2.0 g o monome was placed in o a Schlenk
ube equipped wi h a magne ic s i e , ollowed by he addi ion o he
espec i e amoun o AIBN o a o d an ini ia o concen a ion o 0.5
mol%. The sys em was subjec ed o h ee consecu i e eeze– haw cycles
employing liquid ni ogen and inally pu ged wi h d y N
2
. The en i e
sys em was imme sed in an oil ba h he mos a ed a 70 ◦C and s i ed o
48 h. A e comple ing he eac ion ime, he mix u e was exposed o ai ,
dissol ed in 10 mL o N,N
′
-dime hyl o mamide (DMF), p ecipi a ed in o
150 mL o me hanol and il e ed. The abo e p ocess was epea ed h ee
imes. Finally, he ob ained whi e powde s we e d ied a 120 ◦C in a
acuum o en o 72 h p io o cha ac e iza ion. The nomencla u e
chosen o he ob ained polyme s was PSO
2
mNORI, PSO
2
NORI, PSO
2
-
mADAI and PSO
2
ADAI, which we e ob ained di ec ly om he poly-
me iza ion o monome s 2a, 2b, 2c and 2d, espec i ely. Con e sion
alues o 72%, 64%, 58% and 50% we e calcula ed o PSO
2
mNORI,
PSO
2
NORI, PSO
2
mADAI and PSO
2
ADAI, espec i ely.
3. Resul s and discussion
The expe imen al pa o he p esen p ojec began wi h he design
and p epa a ion o he co esponding monome s ha would allow he
ob ainmen o his new amily o polyi acona es. Scheme 1 illus a es he
syn he ic ou e employed o achie e he p epa a ion o he de ised
monome s 2a, 2b, 2c and 2d.
All monome s we e de i ed om i aconic anhyd ide (1), which was
success ully syn hesized om i aconic acid using well-es ablished
me hods [43]. Subsequen ly, his anhyd ide was eac ed unde e lux
condi ions wi h he co esponding alcohols de i ed om no bo nane
and adaman ane s uc u es. This induced he opening o he anhyd ide
s uc u e, leading o he o ma ion o mono i acona e es e s 1a, 1b, 1c
and 1d in yields anging om egula o good. This was con i med by
1
H
and
13
C NMR analysis (Figs. S1 – S5). Subsequen ly, each monoes e
unde wen a second es e i ica ion p ocess using he S eglich p o ocol.
[44] This led o he inco po a ion o sul one en i ies in o he inal
monome ic s uc u es, esul ing in he ob ainmen o dii acona es 2a,
2b, 2c and 2d. This was also con i med by
1
H and
13
C NMR analysis
(Figs. S6 – S9). Impo an ly, all dii acona es we e success ully poly-
me ized using con en ional adical polyme iza ion unde bulk condi-
ions, as depic ed in Scheme 2.
These polyi acona es, all con aining sul onyl g oups as high dipole
momen en i ies, can be ca ego ized in o wo amilies based on he
s uc u e o he a ached alipha ic cycle. In his sense, one amily would
be ep esen ed by PSO
2
mNORI and PSO
2
NORI, ha ing no bo nane-like
s uc u es, wi h he only s uc u al di e ence be ween hem being he
Scheme 1. Syn he ic ou e o ob aining he e o – unc ionalized i acona e monome s.
S. Bona dd e al.
Reac i e and Func ional Polyme s 196 (2024) 105842
5
p esence o a me hylene space uni in PSO
2
mNORI. Likewise, he sec-
ond amily includes PSO
2
mADAI and PSO
2
ADAI, bo h ea u ing
adaman ane-based moie ies. Once mo e, he p ima y s uc u al
dis inc ion be ween hem lies in he p esence o he me hylene uni in
PSO
2
mADAI. The con e sion alues o all ob ained polyme s we e in
he ange o 50–72%. In e es ingly, when compa ing wi hin he same
amily, sys ems wi h he space uni exhibi ed highe con e sion alues.
Con e sely, compa ing specimens wi h o wi hou he space uni
e ealed ha hose bea ing no bo nane g oups also exhibi ed highe
con e sions han hose wi h adaman yl pendan g oups. This can be
a ibu ed o he highe s e ic hind ance gene a ed: 1) he absence o he
me hylene space uni , b inging he alipha ic cycle close o he poly-
me izable sec ion o he monome , and 2) he eplacemen o no bo -
nane s uc u es by bulkie adaman ane en i ies. [45–48]
The s uc u al cha ac e iza ion o hese polyi acona es was i s
add essed h ough FTIR analysis, whe e spec a o he ob ained poly-
me s a e displayed in Fig. 1.
The FTIR analysis e ealed e y simila spec a among he ou
Scheme 2. P epa a ion o sul onyl-con aining polyi acona es h ough bulk adical polyme iza ion.
Fig. 1. FTIR spec a eco ded o PSO
2
mNORI (A), PSO
2
NORI (B), PSO
2
mADAI (C) and PSO
2
ADAI (D).
S. Bona dd e al.
Reac i e and Func ional Polyme s 196 (2024) 105842
6
specimens, which was an icipa ed due o he no able simila i ies in hei
chemical s uc u es. In ligh o his, h ee colo ed egions we e high-
ligh ed in all spec a o iden i y he g oups o signals ha would con i m
he p esence o he desi ed unc ionali ies. The yellow zone, de ined
be ween 3000 and 2800 cm
−1
, encompasses wo ib a ional bands
a ising om he C – H linkages o igina ing om he alipha ic con en in
he polyme backbone. Addi ionally, i includes a signi ican con ibu-
ion o −CH−and −CH
2
−uni s belonging o no bo nane and ada-
man ane pendan s uc u es. Indeed, his g oup o signals s ands ou by
hei ema kable in ensi ies, being he mos in ense in he PSO
2
mADAI
and PSO
2
ADAI spec a due o he p esence o adaman ane uni s. In e -
es ingly, he second band appea ing a lowe wa enumbe alues
(⁓2860 cm
−1
) has been p e iously assigned o ce ain ib a ional
modes o C – H linkages p esen in his class o igid cycles [49]. A lowe
wa enumbe alues, wi hin he cyan zone, an in ense and sha p signal
cen e ed a ound ⁓ 1735 cm
−1
would accuse he p esence o he ypical
ca bonyl s uc u es o polyi acona es. C ucially, he p esence o sul one
g oups was con i med by iden i ying he wo cha ac e is ic bands o his
dipola en i y cen e ed a ⁓ 1315 cm
−1
and ⁓ 1132 cm
−1
(highligh ed
in g ay), co esponding o he symme ic and asymme ic s e ching
mo ions o hese unc ionali ies, espec i ely [50]. Finally, indica ed by
black a ows, a signal cen e ed a app oxima ely 1180 cm
−1
can be
iden i ied in all spec a. This co esponds o he ib a ional mo ions o C
– O – C linkages ha a e pa o he es e g oups p esen in he mono-
me ic uni s o hese ma e ials. As a complemen o he FTIR analysis, he
chemical s uc u e o hese polyme s was also s udied by
1
H and
13
C
NMR, and he esul s a e shown in Fig. 2 and Fig. S10, espec i ely.
NMR analysis o he ou ob ained polyme s success ully iden i ied
dis inc agmen s belonging o hei espec i e monome ic s uc u es.
In his con ex , he p esence o sul onyl-con aining s uc u es (blue
agmen s in Fig. 2) was disce ned in all
1
H NMR spec a. This was
p ima ily accomplished by iden i ying he me hylene uni s om he 2-
me hylsul onyl e hyl pendan g oups. Mo e no ably, he cha ac e is ic
signal a ibu ed o he me hyl g oup di ec ly a ached o he sul onyl
moie y p o ided c ucial con i ma ion. Con e sely, he p esence o no -
bo nane o adaman ane s uc u es ( ed agmen s in Fig. 2) is subs an-
ia ed by he mul i ude o densely packed signals appea ing a high ield.
These signals exhibi signi ican in ensi y and a no able deg ee o
o e lap, making i di icul o assess he main-chain p o ons labeled as 1
and 2, which should appea in he ange be ween 3.0 and 2.0 ppm as
e idenced in p e ious polyi acona e sys ems. Addi ionally, hese signals
end o exhibi a low in ensi y and de ini ion due o ac ici y phenom-
ena, a ec ing hei isualiza ion. [34,42,43,51] Simila ly, he analysis
o
13
C NMR spec a – shown in Fig. S11 – co obo a es he p e iously
ex ac ed in o ma ion. Success ul signal assignmen o he a ious
ca bon nuclei was accomplished, wi h he excep ion o ce ain main-
chain ca bon a oms (e.g., ca bon C), likely due o i s o e lap wi h he
DMSO sol en signal. Thus, by complemen ing he FTIR and NMR an-
alyses, he s uc u e o he ob ained polyme s can be con i med.
The e o e, once demons a ed, hei mac omolecula na u e was
Fig. 2.
1
H NMR spec a egis e ed o PSO
2
mNORI (A), PSO
2
NORI (B), PSO
2
mADAI (C) and PSO
2
ADAI (D).
S. Bona dd e al.
Reac i e and Func ional Polyme s 196 (2024) 105842
7
con i med by gel pe mea ion ch oma og aphy (GPC), h ough which
hei a e age molecula weigh s, along wi h hei dispe si y indexes (Ð),
we e ob ained. The esul s a e summa ized in Table 1.
The molecula weigh s ob ained o PSO
2
mNORI, PSO
2
NORI and
PSO
2
mADAI co ela e well wi h ou p e ious epo s on he p epa a ion
o coun e pa s bea ing ni ile g oups as dipola en i ies [43]. An
excep ion a ises wi h PSO
2
ADAI, which exhibi s a molecula weigh
alue app oxima ely one o de o magni ude lowe . O e all, conside ing
he expe imen al condi ions employed du ing he polyme iza ion s ep,
he ob ained alues a e signi ican ly lowe han hose epo ed in p e-
ious s udies conce ning he p epa a ion o o he polyi acona e ma e-
ials [43,45]. We belie e ha he inco po a ion o no bo nane and
adaman ane g oups in o he monome ic uni s signi ican ly a ec s hei
addi ion/ eac i i y owa d he e minal adicals o g owing chains, and
he main a gumen suppo ing his should be he inc eased s e ic hin-
d ance ha hese monome s expose due o he p esence o hese bulky
s uc u es. Based on he abo e, i could be sugges ed ha he lowe
molecula weigh o PSO
2
ADAI may be a ibu ed o i s monome uni ,
which, among all es ed monome s, p esen s he highes s e ic hin-
d ance. Con e sely, conce ning he Ð alues, all o hem all wi hin he
an icipa ed ange o his ype o con en ional adical polyme iza ion. I
should be no ed ha , in acco dance wi h p e ious s udies he a e age
molecula weigh and dispe si y alues exhibi ed by hese ypes o
ma e ials should no subs an ially a ec hei pola iza ion p ope ies
[20,52]. This is because he pola iza ion phenomena o dipola glass
polyme s p ima ily depend on he local mo emen s o dipola s uc u es
a he han long- ange mo ions.
The he mal p ope ies o hese new polyi acona es we e e alua ed
in e ms o TGA and DSC analyses, and he esul s a e shown in Fig. 3
and summa ized in Table 2.
TGA analysis e eals ha all samples exhibi ema kably simila
deg ada ion p o iles (Figs. 3 A – D), wi h wo disce nible deg ada ion
s eps cha ac e ized by empe a u es T
MD1
and T
MD2
. I is impo an o
no e ha , in all cases, >80% o he mass loss occu s du ing he i s s ep.
A guably, a ious phenomena occu ing simul aneously wi hin he
empe a u e ange ini ia e he clea age o chemical bonds p esen in he
ma e ials. This could be b ough abou by he clea age o pendan
g oups o e en he andom agmen a ion o he polyme backbone,
leading o he gene a ion o adical species ha , unde hese high em-
pe a u e condi ions, can ini ia e depolyme iza ion p ocesses. In his
sense, low molecula weigh species would be gene a ed and ola ilized
as deg ada ion p oduc s. Simila ly, albei wi h a signi ican ly lowe
mass con ibu ion, he second s ep may be associa ed wi h he deg a-
da ion o ce ain chemical s uc u es ha pe sis a e he i s s ep.
Howe e , he he mal s abili y o hese ma e ials is be e cha ac e ized
by he onse deg ada ion empe a u e (T
i
), de ined in his case as he
empe a u e a which he ma e ial loses 5% o i s ini ial weigh . Based
on he abo e, i is e iden ha all he ob ained polyi acona es
commence deg ada ion well abo e 250 ◦C, a condi ion es ablished o
deem as ma e ials possessing adequa e high- he mal esis ance o
applica ion as dielec ic media [16]. In line wi h ou p e ious epo on
bulky polyi acona es [43], i is e iden once again ha he ma e ials
wi h monome ic s uc u es lacking me hylene space uni s (PSO
2
NORI
and PSO
2
ADAI) exhibi ed lowe T
i
and T
MD1
alues han hei coun-
e pa s, PSO
2
mNORI and PSO
2
mADAI (Table 2). This lowe he mal
esis ance has been p e iously a ibu ed o a possibly mo e igid
s uc u e ha would esul in a less s able sys em agains bond
ib a ions induced by he mal ene gy. Impo an ly, hese samples
possess a ma kedly highe he mal s abili y han PSO
2
MeiT (T
i
=
277 ◦C), a dipola glass polyme p e iously epo ed by us, consis ing o
a sul one-con aining polyi acona e ob ained a e he eplacemen o
no bo nane/adaman ane s uc u es by me hyl uni s [34].
In DSC analysis, as shown in Fig. 3E, i is e iden ha all ob ained
polyme s display an amo phous beha io , comple ely de oid o c ys-
alliza ion/mel ing phenomena. This ul ills a c ucial c i e ion o
de ining hem as dipola glass polyme s. Fu he mo e, hese ma e ials
dis inguish hemsel es by exhibi ing glass ansi ion empe a u es (T
g
,
indica ed by black a ows) well abo e oom empe a u e, su passing he
100 ◦C h eshold (Table 2). The ele a ed T
g
alues can be a ibu ed o
he p esence o no bo nane/adaman ane s uc u es, which, owing o
hei bulkiness and igid na u e, augmen he igidi y o he mac omo-
lecula s uc u es. Expe imen ally, he ole o hese cyclic en i ies in
ele a ing T
g
was demons a ed by compa ing hese esul s wi h he T
g
alue o PSO
2
MeiT, epo ed a 101 ◦C, e en hough he la e exhibi ed
a signi ican ly highe molecula weigh [34]. Ano he in iguing
obse a ion a ises when compa ing he T
g
alues be ween PSO
2
mNORI
and PSO
2
NORI, whe e a no able inc ease o app oxima ely 32 ◦C was
achie ed by simply emo ing he me hylene space uni be ween he
no bo nane s uc u e and he polyme backbone. This could be a ib-
u ed o a po en ially a o able con ibu ion o he ee olume wi hin
he sys em ha hese space uni s could o e , whe e he absence o hese
CH
2
uni s would dec ease he deg ees o eedom o he bulky pendan
g oups, es ic ing hei possibili y o achie e di e en spa ial o ien a-
ions wi hin he ma e ial’s s uc u e. On he con a y, o PSO2mNORI,
he g ea e o ien a ional disposi ions a ailable o he no bo nane
s uc u es could a o an inc emen o he ee olume in he ma e ial,
esul ing in a lowe T
g
alue. Unexpec edly, his end was no obse ed
in he case o PSO
2
mADAI and PSO
2
ADAI, likely due o he ma kedly
lowe molecula weigh exhibi ed by PSO
2
ADAI since, as is well known,
he e is a close dependence be ween T
g
and molecula weigh in poly-
me ic ma e ials. [53,54] Ne e heless, his sugges s ha in he e en o
success ully p epa ing a PSO
2
ADAI specimen wi h an inc eased molec-
ula weigh , signi ican ly highe T
g
alues could be an icipa ed. Finally,
as a no ewo hy end, when compa ing hese polyme s wi h hei
coun e pa s ea u ing ni ile g oups as dipola en i ies, he o me
exhibi ed highe T
g
alues. Conside ing ha molecula weigh alues
a e on he same o de o magni ude, he abo e esul could be ela ed o
s onge dipola in e ac ions wi hin he sul one-con aining specimens.
This could also be e lec ed in he highe -densi y alues ha he sul one-
bea ing sys ems exhibi ed agains hose wi h ni ile moie ies [34]. In
his con ex , densi y alues o 1.28, 1.24, 1.22 and 1.20 g/cm
3
we e
ob ained o PSO
2
mNORI, PSO
2
NORI, PSO
2
mADAI and PSO
2
ADAI,
espec i ely.
A e comple ing he he mal cha ac e iza ion o hese ma e ials,
hei dielec ic p ope ies we e e alua ed in e ms o BDS measu e-
men s. Fig. 4 displays isoch onal measu emen s o he dielec ic con-
s an (
ε
’), dielec ic loss (
ε
”) and loss ac o (Tan(δ)) pa ame e s a
di e en equencies and empe a u es o all ob ained polyi acona es.
Isoch onal ep esen a ions a e pa icula ly use ul o di ec ly
obse ing how
ε
’,
ε
” and Tan(δ) pa ame e s a y wi h changes in e-
quency and empe a u e. Impo an ly, hey acili a e he isual assess-
men o any elaxa ion phenomena occu ing in he ma e ial as
empe a u e a ies. I is wo h no ing ha all ob ained polyme s exhibi
a simila dielec ic esponse cha ac e ized by closely ma ching p o iles
ε
’,
ε
” and Tan(δ). This ou come was an icipa ed due o he s uc u al
simila i ies be ween hem. Rega ding he dielec ic cons an , a quali a-
i e inspec ion o
ε
’ p o iles e eals an inc ease in his pa ame e as he
empe a u e ises. This co esponds well wi h he he mal ac i a ion
needed o dipola en i ies o o e come he po en ial ene gy ba ie s
imposed by hei su oundings [55,56]. This inc ease is ma ked by wo
dis inc jumps: he i s occu ing a low empe a u es (app oxima ely –
100 ◦C) and he second becoming appa en om ⁓ 100 ◦C onwa ds. I is
no ewo hy ha be ween hese jumps, a sligh bu consis en ise in
ε
’ is
Table 1
Numbe (M
n
) and weigh (M
w
) a e age molecula weigh s along wi h dispe si y
alues (Ð) o syn hesized polyme s.
PSO
2
mNORI PSO
2
NORI PSO
2
mADAI PSO
2
ADAI
M
n
(g/mol) 1.23 ×10
4
2.99 ×10
4
3.10 ×10
4
3.08 ×10
3
M
w
(g/mol) 2.29 ×10
4
6.05 ×10
4
6.07 ×10
4
4.43 ×10
3
Ð 1.86 2.02 1.96 1.44
S. Bona dd e al.
Reac i e and Func ional Polyme s 196 (2024) 105842
8
obse ed. These a ia ions in
ε
’ can be co ela ed wi h
ε
” p o iles
h ough di e se elaxa ion phenomena. In his sense, i can be seen ha
in all cases, he ab up inc ease in
ε
’ a low empe a u es mani es s as a
clea peak in he
ε
” p o iles (labeled γ), indica ing he occu ence o
molecula elaxa ion phenomena.
D awing on p e ious dielec ic in es iga ions on polyme hac yla es
and polyi acona es, especially o PSO
2
MeiT, his γ elaxa ion can p i-
ma ily be a ibu ed o he o ien a ional mo ions o sul one en i ies
[20,34,52]. We use “p ima ily” he e, as i has been demons a ed in pas
epo s ha bo h ca bonyl species in polyi acona es, ac ing as dipola
en i ies in hei espec i e monome ic uni s, con ibu e o pola iza ion
h ough di e en elaxa ion p ocesses known as β
FAST
and β
SLOW
an-
si ions [57]. Ca bonyl species sepa a ed by a me hylene uni om he
polyme backbone a e esponsible o β
FAST
elaxa ion, which occu s
wi hin he same empe a u e ange as γ elaxa ion. Howe e , he
dielec ic s eng h o hese molecula mo ions is no ably lowe han ha
p oduced by sul ones. Thus, i is easonable o conside sul one en i ies
as he main d i e s o hese γ elaxa ions and, consequen ly, o he
pola ized s a e exhibi ed by hese ma e ials. Impo an ly, he maxima o
γ elaxa ions a 1 Hz a e cen e ed a −96 ◦C, −101 ◦C, −98 ◦C and –
97 ◦C o PSO
2
mNORI, PSO
2
NORI, PSO
2
mADAI and PSO
2
ADAI,
Fig. 3. TGA (A, B, C and D) and DSC (E) he mog ams egis e ed o polyi acona es. T
g
s a e indica ed by black a ows.
Table 2
The mal deg ada ion onse empe a u e (T
i
), maximum weigh loss a e em-
pe a u e (T
MD
), esidue pe cen age (R) and glass ansi ion empe a u e o he
ob ained polyi acona es.
Sample T
i
(◦C) T
MD1
(◦C) T
MD2
(◦C) R (%) T
g
(◦C)
PSO
2
mNORI 299 329 472 12 111
PSO
2
NORI 297 320 453 10 143
PSO
2
mADAI 319 339 426 7 166
PSO
2
ADAI 301 324 392 9 136
S. Bona dd e al.
Reac i e and Func ional Polyme s 196 (2024) 105842
9
espec i ely, indica ing ha sul one mo emen s a e ac i e and hus
con ibu e o pola iza ion om ema kably low empe a u es.
Con e sely, ca bonyl species di ec ly a ached o he polyme main
chain begin o con ibu e o hei molecula mo ions (β
SLOW
ansi ions)
a empe a u es abo e – 50 ◦C [34,57]. Fo cla i y, in Figs. 4 B, E, H, K
β
FAST
and β
SLOW
ansi ions ha e been g ouped oge he and labeled as β
con ibu ions. I is impo an o no e ha since γ, β
FAST
and β
SLOW
mo-
lecula mo ions occu a empe a u es below he T
g
, hese sub-T
g
Fig. 4. Isoch onal scans o
ε
’,
ε
” and Tan(δ) o PSO
2
mNORI (A, B, C), PSO
2
NORI (D, E, F), PSO
2
mADAI (G, H, I) and PSO
2
ADAI (J, K, L).
Scheme 3. Assignmen o molecula mo ions o he obse ed dielec ic elaxa ions in isoch onal spec a.
S. Bona dd e al.
