Comonomer Reactivity Ratios Research Articles

Study of amphiphilic poly(1-dodecene- co- para-methylstyrene)- graft-poly (ethylene glycol): Part I. Preparation of poly(1-dodecene- co- para-methylstyrene) copolymer and its molecular weight regulation

Poly(1-dodecene- co- para-methylstyrene) copolymers with a broad composition range were prepared by an MgCl 2 supported TiCl 4 catalyst. The effects of temperature and hydrogen on catalyst activity were investigated. It was found that catalyst activity reached a maximum at around 60 °C, and then decreased with the rising temperature. Hydrogen showed an activation effect on the Ziegler–Natta catalyst. 1H NMR and 13C NMR spectra showed that para-methylstyrene (pMS) could be effectively and randomly incorporated into the copolymer chains. The single glass transition indicated there was no block sequence in the copolymer. The copolymerization reaction was examined by the reactivity ratios of comonomers and the relatively low reactivity ratios of 1-dodecene and pMS indicated that both of them had little tendency of consecutive insertion and should be homogeneously distributed in the copolymer chains. Furthermore, the molecular weights of copolymers were regulated by chain transfer agents (diethyl zinc and hydrogen) and temperature. The molecular weights reduced greatly with the addition of diethyl zinc and hydrogen and with the increasing temperature.

Studies of silicon-containing maleimide polymers. Part II: Synthesis and properties of poly(styrene-co-brominecontaining maleimide).

AbstractSoluble copolymers of a series of bromine-containing (N-maleimido phenoxy) silane (BMS) monomers with styrene (St) were synthesized by radical polymerization in toluene using 2,2’-azobisisobutyronitrile (AIBN) as initiator. The comonomer reactivity ratios were calculated by the conventional Fineman-Ross and Kelen-Tüdos methods and a nonlinear least-squares Tidwell-Mortimer method. The glass transition temperatures (Tg’s) and thermal degradation of copolymers were determined by differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA) respectively. The introduction of silane side-chain into maleimide (MI) monomers changed the comonomer reactivity ratio with styrene from alternating to azeotropic copolymerization. The curves of Tg’s versus the different compositions of the above synthesized St-BMS copolymers matched a modified Tg’s equation as a increase in the effect of weight ratio on alternating-segment, and an S-shaped curve of deviation in comparison with the Fox’s equation. The MIsegments within these copolymers exhibited a good compatibility and, the flame retardancy of polystyrene could be enhanced via the introduction of Si/Brcontaining maleimide.

Copolymerization of N‐(4‐bromophenyl)‐2‐methacrylamide with n‐butyl methacrylate: Synthesis, characterization and monomer reactivity ratios

AbstractThe monomer, N‐(4‐bromophenyl)‐2‐methacrylamide (BrPMAAm) has been synthesized by reacting 4‐bromoaniline with methacryloyl chloride in the presence of triethylamine (NR3) at 0−5°C. Copolymerization of BrPMAAm with n‐butyl methacrylate (n‐BMA) has been carried out in 1,4‐dioxane by free radical solution polymerization at (70 ± 0.1)°C utilizing 2,2′‐azobisisobutyronitrile (AIBN) as an initiator in different in‐feed ratios. The composition of the copolymer was determined by the elemental analysis. The comonomer reactivity ratios determined by Fineman‐Ross (FR), Kelen‐Tüdös (KT), and extended Kelen‐Tüdös (EKT) methods. The copolymers were characterized by FTIR, 1H‐, and 13C NMR spectroscopic technique. Gel permeation chromatography was employed for estimating the weight–average (Mw) and number–average (Mn) molecular weights and polydispersity index (PDI) of the copolymers. Glass transition temperatures (Tg) were determined by differential scanning calorimetry and found to be characteristic of copolymer composition. As the N‐(4‐bromophenyl)‐2‐methacrylamide content increases, the Tg increases from 339 to 437 K. Thermal stabilities of the homo‐ and copolymers were calculated using thermogravimetric analysis. Thermally stable copolymers were obtained by the incorporation of BrPMAAm units as the initial decomposition temperature of the copolymers increased with the increase in concentration of BrPMAAm units. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Fluorinated copolymers and terpolymers based on vinylidene fluoride and bearing sulfonic acid side‐group

AbstractThe radical co‐ and terpolymerization of perfluoro(4‐methyl‐3,6‐dioxaoct‐7‐ene) sulfonyl fluoride (PFSVE) with 1,1‐difluoroethylene (or vinylidene fluoride, VDF or VF2), hexafluoropropene (HFP), chlorotrifluoroethylene (CTFE), and bromotrifluoroethylene (BrTFE) is presented. Although PFSVE could not homopolymerize under radical initiation, it could be copolymerized in solution under a radical initiator with VDF, while its copolymerizations with HFP or CTFE led to oligomers in low yields. The terpolymerizations of PFSVE with VDF and HFP, with VDF and CTFE, or with VDF and BrTFE also led to original fluorinated terpolymers bearing sulfonyl fluoride side‐groups. The conditions of co‐ and terpolymerization were optimized in terms of the nature and the amount of the radical initiators, of the nature of solvents (fluorinated or nonhalogenated), and of the initial amounts of fluorinated comonomers. The different mol % contents of comonomers in the co‐ and terpolymers were assessed by 19F NMR spectroscopy. A wide range of co‐ and terpolymers containing mol % of PFSVE functional monomer ranging from 10 to 70% was produced. The kinetics of copolymerization of VDF with PFSVE enabled to assess the reactivity ratios of both comonomers: rVDF = 0.57 ± 0.15 and rPFSVE = 0.07 ± 0.04 at 120 °C. The thermal and physicochemical properties were also studied. Moreover, the glass transition temperatures (Tgs) of poly(VDF‐co‐PFSVE) copolymers containing different amounts of VDF and PFSVE were determined and the theoretical Tg of poly(PFSVE) homopolymer was deduced. Then, the hydrolysis of the SO2F into SO3H function was investigated and enabled the synthesis of fluorinated copolymers bearing sulfonic acid functions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1814–1834, 2007

Programmed Synthesis of Copolymer with Controlled Chain Composition Distribution via Semibatch RAFT Copolymerization

It is well-known that controlled/living radical copolymerization (CLRcoP) yields gradient copolymer with the composition varying along chain length. The composition distribution of the as-synthesized product is solely determined by the comonomer reactivity ratios and is thus not well controlled. This work reports the first experimental example of the control over the copolymer composition distribution through semibatch operations. Using styrene (St)/butyl acrylate (BA) as a model system, we synthesized uniform and linear gradient copolymers via semibatch reverse addition−fragmentation chain transfer radical polymerization (RAFT) mediated by benzyl dithioisobutyrate. The comonomer feeding rate profiles for the targeted distributions were designed from a newly developed computer model that was trained from the batch RAFT copolymerizations of St and BA at different monomer compositions. The semibatch copolymerization yielded precise copolymer products having their composition distributions exactly as targeted and the polymerization rate and molecular weight profiles as predicted by the model.

Microstructure determination and thermal studies ofn‐acryloylcarbazole/vinyl acetate copolymers

AbstractCopolymers ofN‐acryloylcarbazole (A) and vinyl acetate (V) were synthesized by bulk polymerization using benzoyl peroxide (BPO) as free‐radical initiator at 65°C in different in‐feed ratios. The composition of the copolymer was determined by1H‐NMR spectrum. The comonomer reactivity ratios, determined by Kelen–Tudos (KT) and nonlinear error‐in‐variables (EVM) methods, wererA= 16.75 ± 1.38,rV= 0.015 ± 0.002, andrA= 16.36,rV= 0.015, respectively. Complete spectral assignments of the1H and13C{1H} NMR spectra of the copolymers were done by the help of distortionless enhancement by polarization transfer (DEPT) and two‐dimensional NMR techniques such as heteronuclear single quantum coherence (HSQC) and total correlation spectroscopy (TOCSY). The methine and methylene carbon resonances were found to be compositional as well as configurational sensitive. The signals obtained were broad pertaining to the restricted rotation of bulky carbazole group. The thermal stability and glass‐transition temperatures (Tg) of the copolymers were found to be dependant on polymer composition and characteristic of rotational rigidity of the polymer chain. Variation in the values ofTgwith the copolymer composition was found to be in good agreement with theoretical values obtained from Johnston and Barton equations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2720–2733, 2007

1-(Bromoacetyl)pyrene, a novel photoinitiator for the copolymerization of styrene and acrylonitrile

A comparative study on photoinitiated solution copolymerization of Styrene (Sty), with acrylonitrile (AN) using pyrene, 1-acetylpyrene, and 1-(bromoacetyl)pyrene (BrPy) as initiators, showed that the introduction of a chromophoric moiety, bromoacetyl (–COCH2Br), significantly increased the photoinitiating ability of pyrene. The kinetics and mechanism of copolymerization of Sty with AN (Sty–co–AN) using BrPy as photoinitiator has been studied in detail. The kinetic data, inhibiting effect of benzoquinone, and electron spin resonance (ESR) studies suggest that the polymerization proceeds via a free radical mechanism. The system followed non-ideal kinetics (R p α[BrPy]0.7[Sty]1.09[AN]1.01) and degradative solvent transfer reasonably explained these kinetic non-idealities. The co-monomer reactivity ratios calculated by using the Finemann–Ross and Kelen–Tudos models were r 1 (Sty) = 0.39 and r 2 (AN) = 0.05. The reactivity ratios strongly indicate that the two monomers enter in almost alternating arrangement along the copolymer chain.

Supported titanium–magnesium catalysts with different titanium content: Kinetic peculiarities at ethylene homopolymerization and copolymerization and molecular weight characteristics of polyethylene

AbstractThe effect of Ti content on the activity of titanium–magnesium catalysts (TMC) and molecular weight distribution (MWD) of polyethylene (PE) produced has been studied. It was found that the activity enhances sharply as Ti content decreases from 0.6 to 0.07 wt %, and shows no significant changes in the Ti content range of 0.6–5.0 wt %. The maximum activity (36 kg PE/mmol Ti × h × bar C2H4) was observed for TMC with the lowest Ti content. The catalyst with low titanium content (∼ 0.1 wt % of Ti) produced PE with narrower MWD (Mw/Mn = 3.1–3.5) as compared to catalysts with higher titanium content (3–5 wt % of Ti; Mw/Mn = 4.8–5.0). New data on the effect of hydrogen on MWD of PE have been found. Increasing hydrogen concentration results in broadening the MWD of PE, especially in the case of TMC with high titanium content. The data presented indicate the heterogeneity of active centers of TMC in the reaction of chain transfer with hydrogen. The data on the ethylene–hexene‐1 copolymerization over TMC with different titanium content are presented. Comonomer reactivity ratios were shown to be independent of the Ti content in TMC. Presumably the difference in activity of these catalysts is mainly caused by the difference in the number of active centers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5436–5442, 2006

Synthesis, Characterization, and Gene Transfer Application of Poly(ethylene glycol-b-ethylenimine) with High Molar Mass Polyamine Block

The study of ethyloxazoline/methyloxazoline (EtOXZ/MeOXZ) copolymerization, initiated by methyl tosylate (MeOTs), showed that (i) incorporation of MeOXZ units into random copolymer becomes effective over DP = 100 and (ii) propagation process proceeds with negligible transfer to monomer up to a DP of 400 despite the presence of MeOXZ in the polymerization medium. These results produced random poly(EtOXZ-co-MeOXZ) copolymers with various molar composition ratios in alkyloxazoline units. The close values found for the comonomer reactivity ratios in acetonitrile (r(1MeOXZ) = 1.18; r(2EtOXZ) = 0.34) implied a random chain organization in short sequences of each repeating unit, which was an important parameter in view of the optimization of their subsequent modification: the alkaline hydrolysis was successfully achieved when the MeOXZ unit content of the polyoxazoline chains reached 75%. Using these results, the diblock copolymer poly(ethylene glycol-b-(ethyloxazoline-co-methyloxazoline)) (poly(EG-b-(EtOXZ-co-MeOXZ))) with high DP was synthesized by cationic copolymerization of EtOXZ/MeOXZ comonomers using CH(3)-PEG(2kDa)-Ts as macroinitiator. The comonomer composition of this new compound was adjusted in order to optimize the hydrolysis step and obtain finally the diblock copolymer poly(ethylene glycol-b-ethylenimine) (poly(EG-b-EI)). The high molar mass of this copolymer was confirmed both by (1)H NMR and SANS measurements. Gene delivery experiments showed that the copolymer has significant DNA transfection capacities.

Studies of novel copolymers for deep‐UV photoresists. I. Synthesis and properties of poly(styrene‐co‐silicon‐containing maleimide)

AbstractSoluble copolymers of a series of (N‐maleimido phenoxy) silane monomers with styrene (St) were synthesized by radical polymerization in toluene using 2,2′‐azobisisobutyronitrile as initiator. The comonomer reactivity ratios were calculated by the conventional Fineman–Ross and Kelen–Tüdos methods and a nonlinear least‐squares Tidwell–Mortimer method. The glass transition temperatures (Tg's) and thermal degradation of copolymers were determined by differential scanning calorimetric and thermogravimetric analysis methods respectively. The introduction of silane side‐chain into maleimide (MI) monomers changed the comonomer reactivity ratio with styrene from an alternating to azeotropic copolymerization. The curves of Tg's versus the different compositions of the synthesized St‐MI copolymers (mentioned earlier) matched a modified Johnston's equation as increasing the effect of weight ratio on alternating segment, and exhibited an S‐shaped curve of deviation in comparison with the Fox's equation. The MI segments within these copolymers exhibited a good compatibility, and the thermal stability and flame retardancy of polystyrene could be enhanced simultaneously via the introduction of silicon‐containing MI. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3369–3375, 2006

1-(Bromoacetyl)pyrene, a novel photoinitiator for the copolymerization of styrene and methylmethacrylate

The photopolymerization of styrene (Sty) with methylmethacrylate (MMA) induced by pyrene (Py), 1-acetylpyrene (APy) and 1-(bromoacetyl)pyrene (BrPy) has been investigated. Py was found to be completely ineffective while APy could just initiate the copolymerization in 15 h. Introduction of a Br in α-methyl group of APy significantly enhanced the polymerization efficiencies. The kinetics and mechanism of bulk copolymerization of Sty with MMA (Sty–co-MMA) using BrPy as a sole photoinitiator has been studied in detail. The kinetic data, inhibiting effect of benzoquinone and ESR studies suggest that the polymerization proceeds via a free radical mechanism. The system follows non-ideal kinetics ( R p α[BrPy] 0.7[Sty] 1[MMA] 1.04) and degradative solvent transfer reasonably explains these kinetic non-idealities. The co-monomer reactivity ratios calculated by using the Finemann–Ross and Kelen–Tudos models were r 1 (MMA)=0.48 and r 2 (Sty)=0.52. The value of k p 2 / k t for the present system is found to be 2.28×10 −5 l/mol/s. IR and NMR analysis confirms the random structure of the copolymer.

Synthesis and characterization ofN‐acryloylcarbazole/methyl methacrylate copolymers

AbstractCopolymers ofN‐acryloylcarbazole (A) and methyl methacrylate (M) were synthesized in different in‐feed ratios. The composition of the copolymer was determined by the help of1H NMR spectrum. The comonomer reactivity ratios determined by Kelen‐Tudos (KT) and nonlinear error‐in‐variables methods wererA= 1.12 ± 0.16,rM= 0.94 ± 0.14, andrA= 1.05,rM= 0.90, respectively. Complete spectral assignments of the1H and13C1H NMR spectra of the copolymers were done by the help of distortionless enhancement by polarization transfer (DEPT) and two‐dimensional NMR techniques, such as heteronuclear single quantum coherence (HSQC), total correlation spectroscopy (TOCSY), and heteronuclear multiple bond correlation (HMBC). The methine, α‐methyl, and carbonyl carbon resonances were found to be sequence sensitive. The signals obtained were broad because of the restricted rotation of bulky carbazole group and the quadrupolar effect of nitrogen present in carbazole moiety. Glass transition temperatures (Tg) were determined by differential scanning calorimetry and were found to be characteristic of copolymer composition. As theN‐acryloylcarbazole content increases, theTgincreases from 378.3 K for poly(methyl methacrylate) to 430.4 K for poly(N‐acryloylcarbazole). Variation inTgwith the copolymer composition were found to be in good agreement with theoretical values obtained from Johnston and Barton equations. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2667–2676, 2006

Synthesis of styrene/methyl methacrylate copolymers by atom transfer radical polymerization: 2D NMR investigations

AbstractCopolymers of styrene and methyl methacrylate were synthesized by atom transfer radical polymerization using methyl 2‐bromopropionate as initiator and CuBr/N,N,N′,N′,N″‐pentamethyldiethylenetriamine as catalyst. Molecular weight distributions were determined by gel permeation chromatography. The composition of the copolymer was determined by 1H NMR. The comonomer reactivity ratios, determined by both Kelen–Tudos and nonlinear error‐in‐variables methods, were rS = 0.64 ± 0.08, rM = 0.63 ± 0.08 and rS = 0.66, rM = 0.65, respectively. The α‐methyl and carbonyl carbon resonances were found to be compositionally and configurationally sensitive. Complete spectral assignments of the 1H and 13C NMR spectra of the copolymers were done by distortionless enhancement by polarization transfer and two‐dimensional NMR techniques such as heteronuclear single quantum coherence and heteronuclear multiple quantum coherence. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2076–2085, 2006

Homopolymer and copolymers of 4‐methacrylamidophenyl‐4‐methoxystyryl ketone with methyl methacrylate: Synthesis, characterization, reactivity ratios, and photocrosslinkable properties

Abstract4‐Aminophenyl‐4‐methoxystyryl ketone (APMSK) was prepared by reacting 4‐aminoacetophenone and 4‐methoxybenzaldehyde in the presence of sodium hydroxide as base catalyst. The methacrylamide monomer, 4‐methacrylamidophenyl‐4‐methoxystyryl ketone (MPMSK), was synthesized by reacting APMSK with methacryloyl chloride in the presence of triethylamine. Free‐radical solution polymerization technique was used to prepare the homo‐ and copolymers of different feed compositions of MPMSK with methyl methacrylate in methyl ethyl ketone solution at 70°C, using benzoyl peroxide as the initiator. The polymers were characterized by UV, IR, 1H‐NMR, and 13C‐NMR spectral techniques. The reactivity ratios of both comonomers were calculated using Fineman–Ross, Kelen–Tüdös, extended Kelen–Tüdös, and a nonlinear error‐in‐variables model (EVM) method using a computer program, RREVM. The molecular weights (M̄w and M̄n) and polydispersity indices of the polymers were determined using size exclusion chromatography. The glass‐transition temperatures of the polymers were determined by differential scanning calorimetry. The thermal stability of the polymers was measured by thermogravimetric analysis in air. The photoreactivity of the polymers was studied in chloroform solutions in the presence and absence of various triplet sensitizers. The effect of concentration of homopolymer and composition of the copolymers on the rate of photocrosslinking of the polymers was investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2006

Synthesis and copolymerisation of fluorinated monomers bearing a reactive lateral group: Part 21. Radical copolymerisation of vinylidene fluoride with 2-hydroperfluorooct-1-ene

The synthesis and the radical copolymerisation of 2-hydroperfluorooct-1-ene (HPO) with vinylidene fluoride (VDF), initiated by tertio-butyl peroxypivalate (TBPPI) at 75 °C, are presented. That fluorinated alkene (HPO) was synthesised in two steps starting from the thermal or redox telomerisation of VDF with C 6F 13I (after purification of the monoadduct compound by rectification) followed by a dehydroiodination in the presence of various alkalies. Their influences are discussed toward the yield of the reaction. The compositions of the resulting random-type copolymers were calculated by means of 19F NMR spectroscopy and allowed one to quantify the respective amounts of each monomeric unit in the copolymer. From the Tidwell and Mortimer method, the reactivity ratios ( r i ) of both comonomers for this copolymerisation were determined showing a higher incorporation of VDF: r VDF = 12.0 ± 3.0 and r F 2 C CH C 6 F 13 = 0.9 ± 0.4 at 74 °C.

Radical copolymerization of vinylidene fluoride with perfluoroalkylvinyl ethers

The radical copolymerization of perfluoromethylvinyl ether (PMVE) and perfluoropropylvinyl ether (PPVE) with vinylidene fluoride (VDF), initiated by tertiobutyl peroxypivalate (TBPPI) and di tertiobutyl peroxide (DTBP), respectively, are presented. The kinetics of copolymerization were investigated for each monomer from series of at least eight reactions for which the initial [VDF] 0/[fluorinated vinyl ether] 0 molar ratios ranged between 20/80 and 80/20. The copolymer compositions of these random-type copolymers were calculated by means of 19F NMR spectroscopy and allowed one to quantify the respective amounts of each monomeric unit in the copolymer. According to the Tidwell and Mortimer method, the reactivity ratios ( r i ) of both comonomers for each type of copolymerization were obtained : r VDF = 3.40 ± 0.40 and r PMVE = 0 at 74 °C; and r VDF = 1.15 ± 0.36 and r PPVE = 0 at 120 °C. Moreover, the glass transition temperatures ( T g’s) of poly(VDF-co-PMVE) and poly(VDF-co-PPVE) copolymers containing different amounts of VDF and PMVE or PPVE, were determined and the theoretical glass transition temperatures of poly(PMVE) and poly(PPVE) homopolymer were deduced.

Photocrosslinkable copolymers based on 4‐acryloyloxyphenyl‐3′‐chlorostyryl ketone and methyl methacrylate: synthesis, comonomer reactivity ratios and UV photosensitivity

AbstractA new photosensitive acrylate monomer having a pendant chlorocinnamoyl moiety (APCSK) was copolymerized with methyl methacrylate (MMA) in different feed compositions in ethyl acetate solution at 70°C using benzoyl peroxide as a free‐radical initiator. The newly synthesized copolymers were characterized by FTIR, 1H and 13C nuclear magnetic resonance (NMR) spectral techniques, as well as by size‐exclusion chromatography. Their thermal behaviour was assessed by thermogravimetric analysis in air and differential scanning calorimetry under nitrogen atmosphere. The copolymers exhibit no phase separation since there is only one glass transition temperature (Tg) value in the region of copolymer composition studied. The reactivity ratios of the comonomers were calculated by adopting linearization methods such as the Fineman–Ross (F‐R), Kelen–Tudos (K‐T) and extended Kelen–Tudos (ExtK‐T) methods, and by a non‐linear error‐in‐variables model method (EVM) using a computer program (RREVM). The results suggest that MMA is more reactive than APCSK and that their copolymerization leads to the formation of random copolymers. The photosensitivity of the copolymer samples was studied in solution as well as in thin films through UV irradiation. The influence of different factors, including solvent nature, concentration, temperature, photosensitizer and copolymer composition, on the rate of photocrosslinking of the photoreactive copolymers was investigated for effective industrial application of these polymers as negative photoresists. Copyright © 2004 Society of Chemical Industry

Reactivity ratios and sequence determination of methacrylonitrile/butyl acrylate copolymers by NMR spectroscopy

Methacrylonitrile/butyl acrylate (M/B) copolymers were prepared by bulk polymerization using benzoyl peroxide as an initiator. The Distortionless Enhancement by Polarization Transfer spectra were used to differentiate between the carbon resonance signals of methyl, methine, methylene and oxymethylene groups in the 13C{ 1H} NMR spectrum of the copolymer (M/B). Comonomer reactivity ratios were determined using Kelen–Tudos and non-linear error in variable methods. Two-dimensional Heteronuclear Single Quantum Coherence and Total Correlated Spectroscopy were used to resolve the complex 1H NMR spectrum and to determine the compositional and configurational sequences of M/B copolymers.

Synthesis and characterization of original functional polymers of tetrafluoroethylene and 4,5,5‐trifluoro‐4‐ene pentyl acetate

AbstractThe bulk radical copolymerization of tetrafluoroethylene (TFE) with 4,5,5‐trifluoro‐4‐ene pentyl acetate (FAc), initiated by tert‐butyl peroxypivalate to synthesize original, functionalized fluorinated poly(TFE‐co‐FAc), was investigated. FAc monomer was prepared from a five‐step process. The copolymerization was carried out in batch at different initial monomer molar ratios ([TFE]o/[FAc]o ranging from 95/5 to 10/90 mol %) and at different initiator concentrations (ranging between 0.075 and 1.100 mol % about the monomers) at 70 °C. All the experiments revealed the production of fluorooligomers as evidenced by an allylic‐transfer reaction from FAc. The microstructure of these copolymers (i.e., the molar percentage of both monomers in the copolymers) was assessed by 19F NMR spectroscopy. From the kinetics of copolymerization, two key characteristics were determined. First, the reaction order to the initiator (being 1.07) and that of FAc monomer (0.85) showed a heterogeneous character of the copolymerization and monomolecular chain‐transfer reaction to FAc. Second, from the Tidwell and Mortimer method, the reactivity ratios of both comonomers were determined, showing a tendency to alternance in a wide range of initial monomeric ratios (30/70–70/30): rFAc = 0.20 ± 0.26 and rTFE = 0.18 ± 0.15. Alfrey and Price's Q and e values of FAc were calculated by Greenley's technique [QFAc = 0.098 (from QTFE = 0.032) and eFAc = 1.23 (vs eTFE = 1.63)], indicating that FAc is a strong electron‐withdrawing monomer as TFE. The normalized monomer‐diad and triad fractions as a function of the polymer composition were obtained from the comonomer sequence‐distribution procedure. The average molecular weights and molecular weight distributions as well as the thermal properties (glass‐transition temperature and decomposition temperature) of the fluorocopolymers were assessed and are discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1693–1706, 2004

Photoresponsive polymers having pendant chlorocinnamoyl moieties: synthesis, reactivity ratios and photochemical properties

New photoreactive homo- and copolymers containing pendant chlorocinnamoyl moieties were respectively synthesized by homopolymerization of corresponding acrylic monomer and copolymerization with glycidyl methacrylate. The diverse structures were characterized by different spectroscopic techniques. The thermal properties of the photosensitive polymers were investigated by thermogravimetric analysis in air and differential scanning calorimetry under nitrogen atmosphere. The compositions of polymers were determined by 1H-NMR analysis. The reactivity ratios of both comonomers were calculated using the conventional linearization methods such as Fineman–Ross, Kelen–Tudos, extended Kelen–Tudos and a non-linear error-in-variables model (EVM) method using a computer program, RREVM, in order to optimize the reaction conditions for industrial applications. The photoreactivity of newly synthesized homo- and copolymers containing pendant chlorocinnamoyl moieties was investigated in solution as well as in thin films. The effects of solvent nature, concentration, temperature, copolymer compositions and photosensitizers on the rate of photocrosslinking of these new photoresponsive polymers were evaluated. Suitable conditions were discussed for using as negative photoresists in industries.