This article was originally published in a journal published byElsevier, and the attached copy is provided by Elsevier for the

author’s benefit and for the benefit of the author’s institution, fornon-commercial research and educational use including without

limitation use in instruction at your institution, sending it to specificcolleagues that you know, and providing a copy to your institution’s

administrator.

All other uses, reproduction and distribution, including withoutlimitation commercial reprints, selling or licensing copies or access,

or posting on open internet sites, your personal or institution’swebsite or repository, are prohibited. For exceptions, permission

may be sought for such use through Elsevier’s permissions site at:

http://www.elsevier.com/locate/permissionusematerial

Autho

r's

pers

onal

co

py

Radical copolymerization of 2,2,2-trifluoroethyl methacrylate with cyano

compounds for dielectric materials: Synthesis and characterization

M. Raihane a, B. Ameduri b,*a Laboratory of Bioorganic and Macromolecular Chemistry, Faculty of Sciences and Techniques, Avenue Abdelkrim Khattabi,

BP 549 40000 Marrakech, Moroccob Laboratory of Macromolecular Chemistry, UMR (CNRS) 5076, Ecole Nationale Superieure de Chimie de Montpellier, 8 Rue Ecole Normale,

34296 Montpellier Cedex 5, France

Received 23 September 2005; received in revised form 16 December 2005; accepted 20 December 2005

Available online 9 March 2006

Abstract

The copolymerization of cyano (nitrile) monomers and a fluoroalkylmethacrylate is used to develop new dielectric polymers containing C–CN

and C–F substituents. Methacrylonitrile (MAN), acrylonitrile (AN) and methylvinylidene cyanide (MVCN) were chosen as cyano monomers.

2,2,2-Trifluoroethyl methacrylate (MATRIF) was used as a fluorinated comonomer. The copolymers based on cyano monomers such as AN, MAN

or MVCN, and MATRIF comonomers were synthesized by radical process initiated by AIBN. The yields of the copolymerizations were ranging

between 40 and 60%. These copolymers were characterized by 1H, 13C, 19F NMR and IR spectroscopy which showed that the percentages of

incorporation of AN and MAN in the copolymers were 45%. However, only 5% of MVCN was incorporated into poly(MVCN-co-MATRIF)

copolymer. Thermogravimetric analyses showed that the thermal decomposition occurred from 200, 230 or 240 8C for copolymers of MVCN,

MAN or AN, respectively, and indicated that the process of degradation depends on the nature of cyano monomer.

# 2006 Elsevier B.V. All rights reserved.

Keywords: Radical copolymerization; 2,2,2-Trifluoroethyl methacrylate; Cyano (or nitrile) monomers; Nuclear magnetic resonance spectroscopy; Thermal

properties

1. Introduction

Polymers containing polar substituents such as cyano

(nitrile) groups are of interest for the development of advanced

electrical and optical materials because of the large dipole

moment arising from the polar substituent (CN) [1]. Due to the

piezoelectric activity of the amorphous and alternating

copolymer of vinylidene cyanide (VCN) and vinyl acetate,

first described by Miyata et al. [2], there has been growing

interest in the copolymerization of cyano monomers with

various acrylic, vinylic or styrenic to study their microstruc-

tures or their pyroelectric and dielectric properties. Vinylidene

cyanide has been copolymerized with comonomers such as

vinylic esters [3], styrene [4], substituted styrenes [5] and

methacrylic derivatives [6]. All these copolymerizations gave

alternating copolymers and their microstructures were char-

acterized by 13C NMR. The best piezoelectric and dielectric

properties were characterized with copolymers including vinyl

esters [7] and substituted styrenes [8]. Other cyano monomers

such as methacrylonitrile and acrylonitrile copolymerized with

vinyl or isopropenylacetate [9] and some of the resulting

copolymers showed interesting pyroelectric properties [10]. In

addition, copolymers based on methylvinylidene cyanide and

vinyl acetate [11] or styrene [5] exhibit interesting dielectric

behavior [12].

The amorphous copolymers have to be poled to active

noncentrosymmetric forms, driving their piezo- or pyroelectric

properties from the cyano dipole. The poling was carried out at

a temperature just below the glass transition temperature of the

(co)polymers. After cooling, a fraction of dipole was aligned in

the field section [2]. The properties of copolymers containing

cyano groups could be improved with a higher concentration of

dipoles. The copolymerization reaction of cyano monomers

with captodative monomers such as 1,1-disubstituted ethylene

having an electron-withdrawing (capto) and an electron-donor

(dative) substituent on the same carbon, could provide new

www.elsevier.com/locate/fluor

Journal of Fluorine Chemistry 127 (2006) 391–399

* Corresponding author. Tel.: +33 4 6714 4368; fax: +33 4 6714 7220.

E-mail address: bruno.ameduri@enscm.fr (B. Ameduri).

0022-1139/$ – see front matter # 2006 Elsevier B.V. All rights reserved.

doi:10.1016/j.jfluchem.2005.12.032

Autho

r's

pers

onal

co

py

materials with interesting electric properties. Copolymers of

vinylidene cyanide, methacrylonitrile and acrylonitrile with

captodative monomers such as a-cyanovinyl acetate [13] and

ethyl a-acetoxyacrylate [14] were synthesized by radical

copolymerization. The microstructure of the resulting copoly-

mers was characterized by 13C NMR, and some reactivity ratios

could be assessed. The copolymers of vinylidene cyanide

exhibit a highly alternating structure, in contrast to those of

copolymers based on methacrylonitrile and acrylonitrile which

were more statistic than alternating.

Other polymers or copolymers having crystalline structures

with large dipole moments can also exhibit high piezo-

electricity when their main chain exhibits an all-trans

conformation. Well-known examples are the poly(vinylidene

fluoride) (PVDF) [15], especially b-type and the crystalline

copolymers of vinylidene fluoride and trifluoroethylene [16–

18]. Vinylidene cyanide was copolymerized with two styrenic

comonomers bearing a fluorinated chain in the para position of

aromatic nuclei. The microstructure of the resulting copoly-

mers was studied by 13C NMR and for one copolymer, a partial

crystallinity was observed, due to their side fluorinated chain

[19].

Polymerization of many fluorinated acrylic monomers was

studied for their physical properties. The performance of a

series of acrylic-based copolymers as protective coating

materials for stone or ancient buildings has been carried out

by comparing them with unfluorinated polymeric analogues

[20,21]. For this purpose, a series of copolymers of

1H,1H,2H,2H-perfluorodocedyl methacrylate and 2,2,2-tri-

fluoroethyl methacrylate with non-fluorinated vinyl ether or

acrylic monomers were synthesized, and applied to limestone

and marble substrates for interesting coating applications [22].

Several fluoroalkylacrylate and methacrylate polymers were

developed and their physical properties studied [23–31].

Dielectric relaxation studies were achieved on a series of

poly(fluoroalkylmethacrylate)s. The a above Tg and g

relaxations below Tg were observed and assigned to reorienta-

tion of segments and local molecular motion of fluoroalkyl side

groups [32].

To develop new dielectric polymers containing C–CN and

C–F substitutents with strong dipole moments, we describe in

this paper the radical copolymerization of cyano (or nitrile)

monomers and a fluoromethacrylate. Methacrylonitrile (MAN),

acrylonitrile (AN) and methylvinylidene cyanide (MVCN)

were chosen as cyano monomers. 2,2,2-Trifluoroethyl metha-

crylate (MATRIF) was used as a fluorinated comonomer. The

copolymers of cyano monomers with electron-donating

monomers such as methyl acrylate [10], or captodative

monomers as methyl a-acetoxylacrylate [19,33], were also

achieved. However, no fluorinated acrylate monomer was used

and that topic represents the objective of this article to elaborate

new dielectric fluoronitrile materials.

2. Results and discussion

2.1. Synthesis of monomers and copolymers

VCN is difficult to prepare and is highly reactive [34].

However, methylvinylidene cyanide (MVCN) was synthesized

in one step, using the Knovenagel reaction, from acetaldehyde

and malononitrile as a compound possessing mobile hydrogen,

in the presence of b-alanine as base [35]. The yields were close

to 80% and better than those obtained when diethylamine was

used (65%) [9]. This monomer was significantly less reactive

than VCN. We have used a weak base such as an amino acid to

avoid oligomerization of MVCN.

Under free radical conditions (AIBN, 60 8C) or from

photoinduced process [9] MVCN did not undergo any

polymerization. When (C6H5)3P, NaCN or 1,4-diazabicy-

clo[2,2,2]octane (DABCO) were used as possible anionic

initiators, the bulk polymerization slowly showed an increase of

viscosity and turned glassy (mainly trimer) [9]. Interestingly, its

copolymerization with electron-rich monomers readily led to

high molecular weight-copolymers in high yields.

2,2,2-Trifluoroethyl methacrylate (MATRIF) can be synthe-

sized from methacryloyl chloride and 2,2,2-trifluoroethanol

under nitrogen in the presence of triethylamine as base and 2,6–

di-tert-butyl-4-methylphenol as inhibitor, according to proce-

dure previously reported [21]. The purification of the MATRIF

monomer was carried out by distillation (b.p.: 100–102 8C/

1 atm).

Copolymers were prepared from equimolar proportions of

cyano monomers and MATRIF mixed with 1 wt.% of initiator

(AIBN) dissolved in a minimum of acetonitrile and heated at

80 8C for 12 h (Scheme 1). The yields of the copolymerizations

were ranging between 40 and 60%.

M. Raihane, B. Ameduri / Journal of Fluorine Chemistry 127 (2006) 391–399392

Scheme 1. Synthetic routes of copolymers based on MATRIF.

Autho

r's

pers

onal

co

py

2.2. Spectroscopic characterizations, microanalyses and

GPC

Fig. 1 represents the infrared spectrum of poly(AN-co-

MATRIF) copolymer. Vinylic bond absorbances (C C) of

MATRIF and AN at 1638 and 1620 cm�1, respectively, are

absent, indicating that the copolymerization reaction has

occurred. Characteristic bands of this copolymer are

2989 cm�1 (aliphatic C–H stretch), 2243 cm�1 (CBBN stretch),

1754 cm�1 (C O), 1456–1417 cm�1 (out-of-plane C–H),

1286 cm�1 (aliphatic C–F stretch), 1170–1127 cm�1 (C–O)

and 973 cm�1 (out-of-plane C–H bond). Similar observations

can be made for the IR spectrum of poly(MVCN or MAN-co-

MATRIF) copolymers.

The 19F NMR spectra of these copolymers exhibit a signal

centred at �73 ppm corresponding to CF3 group.

Table 1 summarizes the 400 MHz 1H NMR chemical shifts

of the different groups observed in the spectra of three

copolymers of MATRIF. For example, the 1H NMR spectrum of

poly(AN-co-MATRIF) copolymer is given in Fig. 2.

The assignments were deduced from the comparison with

those of the homopolymers of cyano monomers [36,37] and

homopolymer and copolymers of MATRIF [22,24]. The spectra

showed the chemical shifts of different protons in the

copolymers. Peaks assigned to vinylic protons (5.6 and

6.2 ppm for AN; 5.8 ppm for MAN; 2.25 and 7.7 ppm for

MVCN; 5.6 and 6.2 ppm for MATRIF) were absent in these

spectra. The resonance of methylenic protons of the main chain

was observed in the range 0.8–1.5 ppm. The singlet at 2.9 ppm

was attributed to water present in the solvent (DMSO). The

composition of the copolymers can be calculated by measuring

integrals of some characteristic peaks in the 1H NMR spectra.

For example, in poly(AN-co-MATRIF) copolymer, the areas of

the signals of CH3 assigned to MATRIF (I1) in the range 0.8–

1.5 ppm and the methylenic protons CH2 (I2) in the range 1.5–

2.4 ppm show that the calculated percentage of AN in the

copolymer, using equation below, is close to 44.

AN ðmol %Þ ¼ 3I2 � 2I1

3I2

� 100 (1)

The result of elemental analysis (%N = 5.1) of the poly(AN-

co-MATRIF) copolymer is in good agreement within this

incorporation ratio. Table 2 shows the molar percentage of

incorporated cyano monomer calculated from elemental

analyses and assessed by 1H NMR in the copolymers of

MATRIF. The copolymer compositions of acrylonitrile with

non-fluorinated acrylic such as ethyl acrylate [38] and methyl

methacrylate [39] were calculated using elemental analyses.

The incorporation of AN was close to 41 and 53%, respectively,

and shows that the lateral CF3 group affects slightly the

M. Raihane, B. Ameduri / Journal of Fluorine Chemistry 127 (2006) 391–399 393

Fig. 1. Infrared spectrum of poly(AN-co-MATRIF) copolymer.

Table 1

Assignments of 1H NMR chemical shifts /ppm for the copolymers of 2,2,2-trifluoromethacrylate (MATRIF)

Type of proton Poly(AN-co-MATRIF) Poly(MAN-co-MATRIF) Poly(MVCN-co-MATRIF)

CH2 (main chain) 1.5–2.4 1.7–2.4 1.5–2.5 (MATRIF)

CH (AN) 2.6–3.2 – –

CH3 (MATRIF) 0.8–1.5 0.8–1.7 0.5–1.5

CH3 (MVCN) – – 0.5–1.5

CH3 (MAN) – 0.8–1.7 –

CH2CF3 (MATRIF) 4.6 4.6 4.6

CH (MVCN) – – 4.4–4.8

Autho

r's

pers

onal

co

pyreactivity of AN toward MATRIF comonomer. The presence of

methyl in the main chain group in the MATRIF increases the

reactivity comparatively to the corresponding fluorinated

acrylate, MATRIF being considered as a captodative monomer

with a low donor effect arising from the methyl group. The

same conclusion can be proposed for the copolymer of MAN.

Table 2 shows also that the molar percentage of MVCN in the

copolymer is very low (5%). On the other hand, MVCN

monomer is less reactive towards the growing chain terminated

by MATRIF radicals. Due to the presence of the gem dicyano

groups, MVCN is an electron-deficient trisubstituted ethylene,

that copolymerizes easily with such electron-rich monomers as

substituted styrenes [5], vinyl acetate [11] and N-vinylpyrro-

lidone [40] to give high yields of high molecular weight

copolymers. However, it does not copolymerize with poor

electron monomers. As mentioned above, MATRIF is a

captodative monomer which bears, on the same carbon, a

strong electron-withdrawing group (CO2CH2CF3) and a low

donor group (CH3). Overall, this monomer can be qualified as a

poor electron inductive monomer. Hence, MVCN monomer

exhibits repulsive effects [9] when adding MATRIF comono-

mer and contains high proportions of MATRIF monomer

because MVCN does not homopolymerize giving trimer only.

The various resonances in 13C NMR spectra of copolymers

of MATRIF were assigned by comparing them with the spectra

of the homopolymers [24–37]. Table 3 summarizes the 13C

NMR chemical shifts of these copolymers and Fig. 3 shows the13C NMR spectrum of poly(MAN-co-MATRIF) copolymer.

As the percentage of MVCN in the copolymer is low, the

spectrum of the poly(MVCN-co-MATRIF) copolymer is

similar to that of homopolymer of MATRIF [24]. The chemical

shifts of CH3, quaternary carbon C(CH3), CH2 (in the

backbone), and also C O, are very close to those of free

radical poly(methyl methacrylate), while the CF3 is effective on

the resonance of the carbon in the O–CH2 group which is

shifted to lower field [24]. The replacement of H-atom by CF3

group in MATRIF does not seem to affect the interactions

between incoming monomer and the last inserted monomer unit

M. Raihane, B. Ameduri / Journal of Fluorine Chemistry 127 (2006) 391–399394

Fig. 2. 1H NMR spectrum of poly(AN-co-MATRIF) copolymer recorded in deuterated DMSO (DMSO-d6).

Table 2

Percentage of MATRIF incorporated in various copolymers calculated from elemental analyses or 1H NMR

Copolymers Elemental analyses 13H NMR % molar (cyano monomer)

% of atom % molara (cyano monomer)

N (%) O (%) F (%)

Poly(AN-co-MATRIF) 5.1 15.4 27.5 43.3 44.0

Poly(MAN-co-MATRIF) 5.4 46.8 46.9 46.8 45.0

Poly(MVCN-co-MATRIF) 0.9 18.5 33 5.1 4.6

a Values of the percentage of incorporated cyano monomer calculated from arithmetic mean of nitrogen, oxygen and fluor percentage.

Autho

r's

pers

onal

co

py

side chains in spite of the change of polarity involved [24]. The

triads concentration for syndiotactic (rr), heterotactic (mr) and

isotactic (mm) can be assessed from numerical integral of the

resonance from C O, I3, I4 and I5, respectively.

rr ð%Þ ¼ I3

I3 þ I4 þ I5

� 100 (2)

The expansion of the 166–183 ppm region assigned to the

carbonyl group in the 13C NMR spectrum of poly(MVCN-co-

MATRIF) copolymer (Fig. 4) gives 58% (rr), 37% (mr) and 5%

(mm).

By comparing the chemical shifts of the 13C NMR in

poly(MATRIF) with those of poly(MAN-co-para-methylstyr-

ene) copolymer [39], the expansion of the resonance of the CN

in the 13C NMR of poly(MAN-co-MATRIF) copolymer in the

range 110–130 ppm (Fig. 3) shows five peaks: four signals

attributed to CF3 of MATRIF at 118, 122, 125 and 129 ppm, and

one peak at 124 ppm assigned to the resonance of CN of MAN

[39], with I6 and I7 integrals, respectively. The MAN molar

fraction in the poly(MAN-co-MATRIF) was calculated as

follows:

MAN ðmol %Þ ¼ I7

I6 þ I7

� 100 (3)

The measurement of the corresponding integrals of two CN

groups gives 46% of MAN and 54% of MATRIF and is in good

agreement with the results of 1H NMR and elemental analyses

(Table 2). The expanded resonance of the carbonyl group of

poly(MAN-co-MATRIF) showed three broad peaks at 174, 175

and 175 ppm (Fig. 3) corresponding to MATRIF-centered

M. Raihane, B. Ameduri / Journal of Fluorine Chemistry 127 (2006) 391–399 395

Table 3

Assignments of 13C NMR chemical shifts/ppm for the copolymers of MATRIF

Type of carbon Poly(AN-co-MATRIF) Poly(MAN-co-MATRIF) Poly(MVCN-co-MATRIF)

CH2 (main chain) 32.5–37.0 (AN) 45.0–53.0 50.0–55.0

47.0–53.0 (MATRIF)

CH (AN or MVCN) 21.1–28.0 – 29.0–31.0

CH3 (MATRIF) 15.2–20.0 15.0–21.0 16.8–19.5

CH3 (MVCN or MAN) – 21.0–27.0 10.0

CH2CF3 (MATRIF) 59.9–63.0 60.6–62.5 60.0–63.0

CO (MATRIF) 172.9–176.0 172.5–176.0 174.6–178.0

CN and CF3 117.9–131.0 116.0–130.0 116.0–130.0

C(CH3) (MAN, MATRIF) 42.5–46.0 44.5 (MATRIF) 44.7 (MATRIF)

C(CN)2 (MVCN) 30.7–32.3 (MAN) 38.0–40.0 (MVCN)

Fig. 3. 13C NMR spectrum of poly(MAN-co-MATRIF) copolymer recorded in deuterated DMSO (DMSO-d6).

Autho

r's

pers

onal

co

py

triads MAN-MATRIF-MAN as it was observed in the

copolymers based on MAN and methyl a-acetoxylacrylate

[19,33] or MAN and a-cyano vinyl acetate [40]. These peaks

are not well separated compared with those of the alternating

copolymer. Therefore, poly(MAN-co-MATRIF) copolymer

could exhibit a statistical structure.

For the poly(AN-co-MATRIF) copolymer, the percentage of

monomers incorporated was calculated by measuring the

integrals of signals in 13C NMR spectrum of methyl group of

MATRIF (I8) in the range 15–21 ppm and the CN and CF3

peaks (I9) in the 115–130 ppm range, using the relation below:

AN mol % ¼ I9 � I8

I9

� 100 (4)

The copolymer contains approximately a 42:58 mol ratio of

AN:MATRIF in good agreement with the elemental analyses

(Table 2). In the alternating copolymers of poly(VCN-alt-

methyl a-acetoxylacrylate) [13,33] and poly(VCN-alt-methyl

methacrylate) copolymers [41], the resonance of carbonyl

carbon shows three peaks in 0.25:0.50:0.25 ratio arising from

the triad sequences centered in methyl a-acetoxylacrylate. The

expansion of the C O band in poly(AN-co-MATRIF)

copolymer in the range 172–176 ppm shows four multiplets

centred at 173, 174, 175 and 175 ppm confirming the statistical

structure of this copolymer, as it was observed in poly(AN-co-

methyl a-acetoxyacrylate) copolymer [19].

The results of the Alfrey–Price Q–e parameters [42] where

Q and e take into account the stabilization by resonance and the

polar effects of the monomer are commonly used to predict the

monomer reactivity ratios. The Alfrey–Price parameters are

known for AN (Q1 = 0.48, e1 = 1.24) [43], MAN (Q1 = 0.85,

e1 = 0.79) [43], MVCN (Q1 = 0.2, e1 = 2.766) [44] and

MATRIF (Q2 = 1.13, e2 = 0.98) [27]. The values of r1 of cyano

monomers and r2 of MATRIF were determinated from the

following equations, where Q1 and e1 represent the parameters

for cyano monomer while Q2 and e2 are those attributed to

MATRIF:

r1 ¼Q1

Q2

exp½�e1ðe1 � e2Þ� (5)

r2 ¼Q2

Q1

exp½�e2ðe2 � e1Þ� (6)

The calculated values of the reactivity ratios and the product

(r1 � r2) are summarized in Table 4. The values of the product

(r1 � r2) for poly(AN-co-MATRIF) and poly(MAN-co-

MATRIF) copolymers are close to 1, explaining the statistical

structures. This result is in good agreement with the NMR

characterization above. The reactivity ratio of MVCN is close

to zero and means that MVCN does not homopolymerize. The

reactivity ratio of MATRIF is rather high (r2 = 32.5) compared

to some comonomers of MVCN such as vinyl acetate

(r2 = 0.07) or p-chlorostyrene (r2 = 0.78) [45]. As r2 constant

is defined as the ratio between the homopolymerization rate

constant of MATRIF (k22) and the propagation rate of MATRIF

radical onto MVCN monomer (k21), the higher value of r2

indicates that the probability of homopolymerization of

MATRIF is quite high. This result explains the low percentage

M. Raihane, B. Ameduri / Journal of Fluorine Chemistry 127 (2006) 391–399396

Fig. 4. Expansion of the 166–183 ppm zone in the 13C NMR spectrum of poly(MVCN-co-MATRIF) copolymer.

Table 4

Reactivity ratios of cyano monomers (r1) and MATRIF (r2) and the values of the

product (r1 � r2) calculated from the Alfrey–Price parameters

Copolymers r1 r2 r1 � r2

Poly(AN-co-MATRIF) 0.31 3.04 0.93

Poly(MAN-co-MATRIF) 0.87 1.10 0.96

Poly(MVCN-co-MATRIF) 0 32.52 0

ri represents the ratio of the homopropagation rate to the crosspropagation rate.

Autho

r's

pers

onal

co

pyof incorporation of MVCN in the poly(MVCN-co-MATRIF)

copolymer (5%) calculated from elemental analyses and NMR

characterization.

Table 5 shows also the average molecular weights, Mn and

Mw, and polydispersity indices (PDI). The values of the PDI are

in the range 1.58–1.71 corresponding to the radical polymer-

ization without any transfer reaction.

2.3. Thermal properties of the copolymers

Two key thermal properties were studied, glass transition

temperature, Tg, and thermal degradation, Td, determined by

differential scanning calorimetry (DSC) and by thermogravi-

metry analysis (TGA), respectively.

First, all the copolymers analyzed show a sharp transition

from the glassy domain to the viscoelastic one, as evidenced

by the presence of only a neat Tg [28]. Although DSC was

also realized on all samples from 25 to 180 8C, the absence of

any crystallization or melting temperature was noted. The Tg

range, between 77 and 86 8C (Table 6), indicates that the

copolymer exhibited amorphous behavior. As expected, the

Tgs of copolymers of MAN were higher than those of the

copolymers of AN (the replacement of the H-bond by a

methyl group increasing the Tg due to steric effect of CH3).

This result is in good agreement with the Tgs of the

copolymers of vinyl acetate (VAc) with AN and MAN

since the corresponding Tgs were 86 and 102 8C, respectively

[10].

Generally, the copolymers of MVCN exhibit high Tg when

those of poly(MVCN-alt-VAc) (172 8C) [11], poly(MVCN-

alt-styrene) (Tg = 167 8C) [40] or poly(MVCN-alt-vinylpyr-

rolidone) (Tg = 210 8C) copolymers [40] are considered. The

incorporation of polar cyano groups in the copolymer

backbone resulted in an increase of Tg due to chain stiffening

and marked inhibition or rotation about C–C bonds. The

presence of strong CN dipoles in the backbone increases the

interaction between the chains [46]. The low Tg value in the

poly(MVCN-co-MATRIF) copolymer arises from the low

incorporation of MVCN which reduces the interaction

between the main chains.

The thermal degradation of three copolymers, poly(AN-co-

MATRIF), poly(MAN-co-MATRIF) and poly(MVCN-co-

MATRIF) copolymers, was studied by means of thermogra-

vimetry. Table 6 lists their temperatures when the copolymers

start to decompose and their degradation temperature

corresponding to 10% of weight loss. Thermogravimetric

analyses showed that thermal decomposition occurred from

200, 230 and 240 8C for copolymers containing MVCN, MAN

and AN, respectively (Fig. 5). TGA thermograms of these

fluoropolymers indicated that the process of degradation

depends on the nature of the cyano monomer as it was

observed in AN or MAN with methyl a-acetoxylacrylate

copolymers [46].

3. Conclusion

Copolymers containing 2,2,2-trifluoroethyl methacrylate

and cyano monomers (AN, MAN and MVCN) were

synthesized by radical copolymerization initiated by AIBN.

These copolymers were characterized by 1H, 19F and 13C NMR

as well as FT-IR spectroscopies. The copolymer compositions

were determined by NMR spectroscopy and elemental

analyses. The molar percentages of incorporation of AN and

MAN were 44 and 45%, respectively. However, only 5%

MVCN was incorporated in MVCN with MATRIF copolymer.

The values of the product (r1 � r2) calculated from Alfrey–

Price Q–e parameters were 0.93 and 0.96 for poly(AN-co-

MATRIF) and poly(MAN-co-MATRIF) copolymers, respec-

tively, which explain the statistical structures of these

copolymers. The calculated values of the reactivity ratios of

MVCN (r1 = 0) and of MATRIF (r2 = 32.52) explain the low

reactivity of MVCN towards the MATRIF radicals in

poly(MVCN-co-MATRIF) copolymer. DSC and TGA showed

that the copolymers were amorphous and stable up to 200, 230

and 240 8C for copolymers of MVCN, AN and MAN,

respectively.

M. Raihane, B. Ameduri / Journal of Fluorine Chemistry 127 (2006) 391–399 397

Table 5

Average molecular weight, Mn, and Mw, and polydispersity indices (PDI)

Copolymers Mn Mw PDI

Poly(AN-co-MATRIF) 24000 38000 1.58

Poly(MAN-co-MATRIF) 14000 24000 1.71

Poly(MVCN-co-MATRIF) 13000 22000 1.69

Mn and Mw represent the average molecular weights in number and in weight of

the copolymer, respectively.

Table 6

Glass transition and decomposition temperatures of poly(M-co-MATRIF)

copolymers

Copolymer Tg (8C) Td (8C)a T 0d (8C)b

Poly(AN-co-MATRIF) 77 240 345

Poly(MAN-co-MATRIF) 86 230 264

Poly(MVCN-co-MATRIF) 69 200 221

a Td: temperature of beginning of degradation; copolymers heated under

nitrogen at 10 8C min�1.b T 0d: temperature of degradation at 10% of loss weight; copolymers heated

under nitrogen at 10 8C min�1.

Fig. 5. TGA thermograms under nitrogen of copolymers of MATRIF: (a)

poly(AN-co-MATRIF), (b) poly(MAN-co-MATRIF) and (c) poly(MVCN-co-

MATRIF).

Autho

r's

pers

onal

co

py

4. Experimental

4.1. Materials

Methacrylonitrile and acrylonitrile are commercial pro-

ducts (Aldrich Chimie, 38299 St. Quentin, Fallavier, France)

and were distilled under reduced pressure, then stored below

5 8C prior to use. a,a0-Azobisisobutyronitrile (AIBN) was

provided by Aldrich and was purified by recrystallization in

ethanol. Acetonitrile of analytical grade (Aldrich) was

distilled over calcium hydride prior to use. Methylvinylidene

cyanide was synthesized from acetaldehyde and malononitrile

in presence of b-alanine as a base (the details of the procedure

for the preparation of MVCN were reported elsewhere

[34,35]). 2,2,2-Trifluoroethyl methacrylate was used as

fluorinated comonomer, kindly offered by Atofina (now

Arkema), France, and was distilled prior to use in the reaction

mixture.

4.2. Synthesis of copolymers

The radical copolymerization of cyano monomers (AN,

MAN or MVCN) with MATRIF were performed in thick

borosilicate Carius tubes (length 130 mm, internal diameter

10 mm, thickness 2.5 mm, total volume 8 cm3). After introdu-

cing initiator (AIBN, 1 wt.% relative for the monomer

mixture), cyano monomer, MATRIF and acetonitrile under

inert atmosphere, the tube was connected to a vacuum line and

purged several times by evacuating and flushing with helium.

After six thaw–freeze cycles to remove oxygen, the tube was

cooled into liquid nitrogen, sealed under vacuum and placed

into a shaking oven heated at 80 8C for 12 h. After reaction, the

tube was cooled into liquid nitrogen, opened and the total

product mixture was solubilized in dimethyl formamide,

chloroform or tetrahydrofuran and then precipitated from

methanol or pentane. The copolymer formed was isolated by

filtration and dried under vacuum at 80 8C. These copolymers

were characterized by 1H, 13C and 19F NMR, IR, DSC, TGA,

GPC and elemental analysis.

4.3. Analysis

Elemental analyses were performed by the Service Central

d’Analyses (Vernaison, France) and the 1H NMR spectra were

recorded on Bruker Advance DRX 400 (400 MHz service de

RMN de la FR 2151, Vernaison, France). The copolymers were

dissolved in deuterated dimethyl sulfoxide DMSO-d6 or

CDCl3 (20 mg in 0.6 ml of DMSO or CDCl3), with

tetramethylsilane (TMS) as internal reference. The probe

temperature was 90 8C and typical analysis conditions were

as follows: acquisition time 2.7 s and number of scans 200–

300.

The 19F spectra were recorded on Bruker AC 200

(Montpellier, France). The experimental conditions were the

following: flip angle 308, acquisition time 0.7 s, number of

scans 64, pulse delay 5 s and pulse width 5 ms. Chemical shifts

are given in ppm with CFCl3 as the reference.

Infrared spectroscopy measurements were performed in

transmittance with a spectrometer Nicolet 510 P. The accuracy

was �2 cm�1.

Differential scanning calorimetry measurements were

conducted using a Perkin-Elmer Pyris 1 instrument connected

to a micro-computer. The apparatus was calibrated with indium

and n-decane. After its insertion into the DSC apparatus, the

sample was cooled initially to �100 8C for 15 min. Then, the

first scan was made at a heating rate of 20 8C min�1 up to

100 8C, where it remained for 2 min. It was then cooled to

�100 8C at the rate of 320 8C min�1 and left for 10 min at that

temperature before a second scan was started at a heating rate of

20 8C min�1, giving the values of Tg reported herein, taken at

the half-height of the capacity jump of the glass transition.

Thermogravimetry analyses were performed with a Texas

Instrument TGA 51-133 apparatus in nitrogen at a heating rate

of 10 8C min�1 from room temperature up to 500 8C.

Gel permeation chromatography (GPC) or size exclusion

chromatography (SEC) was carried out in tetrahydrofuran at

30 8C, at a flow of 0.8 ml min�1, by means of spectra Physics

Winner Station, a Waters Associate R 401 differential

refractometer and a set of four columns connected in series:

Styragel (Waters) HR4 5m, HR3 analyses, PL Gel (Polymer

Laboratories) 5m, 100 A. Poly(methyl methacrylate) mono-

dispersed standards were used for calibration. Aliquots were

sampled from the reaction medium, diluted with tetrahydro-

furan up to a known concentration (Cp,t) (ca. 4 wt.%), filtered

through a 20 mm PTFE Chromafil membrane and finally

analyzed by GPC under the conditions described above.

Acknowledgements

The authors thank the Agence Universitaire de la

Francophonie (project AUF: 6301PS336), the CNRST (Mor-

occo)–CNRS (France) programme (Chimie 07/05/No. 17691)

and PROTARS III (D13/16), for their financial supports.

References

[1] R. Gerhard-Multhaup, Ferroelectrics 75 (1987) 385–392.

[2] S. Miyata, M. Yoshikawa, S. Tasaka, M. Ko, Polym. J. 12 (1980) 857–860.

[3] Y. Ohta, Y. Inoue, R. Chujo, M. Kishimoto, I. Seo, Polymer 31 (1990)

1581–1588.

[4] Y. Inoue, A. Kashiwasaki, Y. Maruyama, Y.S. Jo, R. Chujo, I. Seo, M.

Kishimoto, Polymer 30 (1989) 698–704.

[5] J.P. Montheard, B. Boinon, A. Belfkira, M. Raihane, Q.T. Pham, Makro-

mol. Chem. 194 (1993) 2839–2850.

[6] Y. Maruyama, Y.S. Jo, Y. Inoue, R. Chujo, S. Tasaka, S. Miyat, Polymer 28

(1987) 1087–1092.

[7] M. Kishimoto, K. Nakajima, I. Seo, European Patent 0264240 Mitsubishi

Petro Chemical Co. Ltd., Chem. Abstr., 109 (1988) 171102h.

[8] A. Belfkira, A. Sadel, J.P. Montheard, G. Boiteux, J.M. Lucas, G. Seytre,

Polymer 34 (1993) 4015–4019.

[9] T.F. Way, H.K. Hall Jr., Polym. Bull. 24 (1990) 151–156.

[10] H.K. Hall Jr., A.B. Padias, G. Chu, H.-Y. Lee, I. Kalinin, M. Sansone, G.

Breckenridge, J. Polym. Sci., Part A: Polym. Chem. 30 (1992) 2341–2347.

[11] J.P. Montheard, B. Boinon, M. Raihane, Q.T. Pham, Polym. Commun. 32

(1991) 567–569.

[12] M. Raihane, J.P. Montheard, G. Boiteux, Macromol. Chem. Phys. 201

(2000) 2365–2370.

M. Raihane, B. Ameduri / Journal of Fluorine Chemistry 127 (2006) 391–399398

Autho

r's

pers

onal

co

py

[13] J.P. Montheard, A. Zerroukhi, I. Ouillon, M. Raihane, J. Macromol. Sci,

Part A: Pure Appl. Chem. A34 (2) (1997) 291–313.

[14] H. Tanaka, T. Okazaki, Y. Tezuka, T. Hongo, Y. Takahashi, Polymer 43

(2002) 1189–1195.

[15] A.J. Lovinger, G.T. Davis, T. Furukawa, M.G. Broadhurst, Macromole-

cules 15 (1982) 323–328.

[16] M. Uchidari, T. Iwamoto, K. Iwata, M. Tamur, Rep. Prog. Phys. Jpn. 22

(1979) 345–361.

[17] R. Seilers, in: J. Scheirs (Ed.), Modern Fluoropolymers, Wiley, New York,

1997 , pp. 487–506 (Chapter 25).

[18] B. Ameduri, B. Boutevin, Well Architectured Fluoropolymers: Synthesis,

Properties and Applications, Elsevier, Amsterdam, 2004.

[19] J.P. Montheard, A. Zerroukhi, I. Ouillon, B. Boinon, Q.T. Pham, Macro-

mol. Rep. A32 (Suppl. 1 and 2) (1995) 1–11.

[20] O. Chiantore, M. Lazzari, M. Aglietto, V. Castelvetro, F. Ciardelli, Polym.

Degrad. Stab. 67 (2000) 461–467.

[21] M. Lazzari, O. Chiantore, V. Castelvetro, Polym. Int. 50 (2001) 863–868.

[22] G. Alessandrini, M. Aglietto, V. Castelvetro, F. Ciardelli, R. Peruzzi, L.

Toniolo, J. Appl. Polym. Sci. 76 (2000) 962–977.

[23] A. Okawara, T. Maekawa, Y. Ishida, M. Matsuo, Polym. Prepr. Jpn. 40

(1991) 3098–3105.

[24] E. Passiglia, M. Aglietto, F. Ciardelli, B. Mendez, Polym. J. 26 (1994)

1118–1123.

[25] V. Castelvetro, L. Montagnini di Mirabello, M. Aglietto, E. Passaglia, J.

Polym. Sci. Polym. Chem. Ed. A (39) (2001) 32–45.

[26] V. Castelvetro, M. Aglietto, F. Ciardelli, M. Lazzari, O. Chiantore, L.

Toniolo, J. Coat. Technol. 74 (2002) 57–66.

[27] B. Boutevin, Y. Pietrasanta, Les Acrylates et Polyacrylates Fluores, Erec,

Paris, 1989.

[28] B. Ameduri, B. Boutevin, G. Kostov, Prog. Polym. Sci. 26 (2001) 105–

187.

[29] B. Guyot, B. Ameduri, B. Boutevin, M. Melas, M. Viguier, A. Collet,

Macromol. Chem. Phys. 199 (1998) 1879–1885.

[30] B. Guyot, B. Boutevin, Eur. Polym. J. 32 (1996) 751–756.

[31] S. Saıda, F. Guittard, S. Geribaldi, Polym. Int. 51 (2002) 1058–1062.

[32] S. Koizumi, K. Tadano, Y. Tanaka, T. Shimidzu, S. Kutsumizu, S. Yano,

Macromolecules 95 (1992) 6563–6567.

[33] J.P. Montheard, A. Zeroukhi, I. Ouillon, M. Raihane, Q.T. Pham, Polym.

Bull. 36 (1996) 709–716.

[34] A.B. Conciatore, L.E. Trapasso, R.W. Stackman, Vinylidene Cyanide

Polymers, Encyclopedia of Polymer Science and Technology, vol. 14, first

ed., John Wiley and Sons, Inc., New York, 1971, p. 581.

[35] J.P. Montheard, B. Boinon, F. Rodriguez, Q.T. Pham, H. Waton, Makro-

mol. Chem. 192 (1991) 341–349.

[36] M.R.S. Weir, J.B. Hyne, Can. J. Chem. 41 (1963) 2905–2908.

[37] Q.T. Pham, R. Petiaud, H. Waton, N.F. Lauros-Darricades, Proton

and Carbon NMR Spectra of Polymers, Prenton Press, New York,

1991 .

[38] A.S. Brar, Sunita, Eur. Polym. J. 7 (1992) 803–808.

[39] A.S. Brar, Sunita, Polymer 34 (1993) 3391–3396.

[40] J.P. Montheard, A. Mesli, A. Belfkira, M. Raihane, Q.T. Pham, Macromol.

Rep. 31A (1&2) (1994) 1–8.

[41] Y. Maruyama, Y.S. Jo, R. Chujo, Y. Inoue, S. Tasaka, S. Miyata, Polymers

28 (1987) 1087–1092.

[42] T. Alfrey, C.C. Price, J. Polym. Sci. 2 (1974) 101–114.

[43] R.Z. Greenley, J. Macromol. Sci. Chem. A9 (4) (1975) 505–516.

[44] J.P. Montheard, B. Boinon, M. Raihane, Q.T. Pham, Macromol. Chem.

193 (1992) 2273–2281.

[45] I. Ouillon, M. Raihane, A. Zerroukhi, B. Boinon, Macromol. Chem. Phys.

198 (1997) 3425–3439.

[46] G.B. Kharas, C.B. Feinberg, Polym. Prepr. Am. Chem. Soc., Polym. Div.

29 (1988) 180–181.

M. Raihane, B. Ameduri / Journal of Fluorine Chemistry 127 (2006) 391–399 399