Synthesis and characterization of novel alternating fluorinated copolymers bearing oligo(ethylene oxide) side chains

The synthesis and characterization of novel poly(CTFE‐g‐oligoEO) graft copolymers [chlorotrifluoroethylene (CTFE) and ethylene oxide (EO)] are presented. First, vinyl ether monomers bearing oligo(EO) were prepared by transetherification of ω‐hydroxyoligo(EO) with ethyl vinyl ether catalyzed by a palladium complex in 70–84% yields. Two vinyl ethers of different molecular weights (three and 10 EO units) were thus obtained. Then, radical copolymerization of the above vinyl ethers with CTFE led to alternating poly(CTFE‐alt‐VE) copolymers that bore oligo(OE) side chains in satisfactory yields (65%). These original poly(CTFE‐g‐oligoEO) graft copolymers were characterized by ¹H, ¹⁹F, and ¹³C NMR spectroscopy. Their molecular weights reached 19,000 g mol^?1, and their thermal properties were investigated while their glass transition temperatures ranged between ?42 and ?36 °C. Their thermogravimetric analyses under air showed decomposition temperatures of 270 °C with 10% weight loss (T_d,10%). These novel copolymers are of potential interest as polymer electrolytes in lithium ion batteries, showing room temperature conductivities ranging from 4.49 × 10^?7 to 1.45 × 10^?6 S cm^?1 for unplasticized material. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Random and block styrenic copolymers bearing both ammonium and fluorinated side‐groups

1H,1H,2H,2H‐Perfluorooctyloxymethylstyrene (FS) was prepared and copolymerized with chloromethylstyrene (CMS). Conventional radical copolymerization of both these aromatic monomers led to poly(CMS‐co‐FS) random copolymers for which CMS was shown to be more reactive than the fluorinated comonomer. Their controlled radical copolymerization based on degenerative transfer, namely iodine transfer polymerization (ITP), led to various poly(CMS)‐b‐poly(FS) block copolymers. Molecular weights of poly(CMS‐co‐FS) copolymers reached 33,000 g mol^?1 while those of poly(CMS)‐b‐ poly(FS) block copolymers were 22,000 g mol^?1. Their composition ranged from 18 to 61 mol.% in FS. These copolymers were modified via a cationization step, aiming at replacing the chlorine atom in CMS unit by a trimethylammonium group, leading to the formation of cationic sites. The resulting functionalized copolymers exhibited different solubilities. If both copolymerization techniques led to water‐insoluble copolymers, the block architecture enabled incorporating lower FS proportion, resulting in more cationic sites. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and characterization of epoxy functionalized cooligomers based on chlorotrifluoroethylene and allyl glycidyl ether

The synthesis of functionalized fluorocooligomers based on chlorotrifluoroethylene (CTFE) and allyl glycidyl ether (AGE) under radical copolymerization is presented. The compositions of comonomers in the cooligomers were determined by three different analyses viz: from ¹H and ¹⁹F NMR spectroscopy by using 1,3‐bis(trifluoromethyl) benzene as the external standard, epoxy equivalent weight value, and elemental analyses. The compositions determined by three methods were matching reasonably well and showed that the resulting poly(CTFE‐co‐AGE) cooligomers exhibit a tendency for alternation. The distribution of the monomers in the cooligomers was proposed based on the assessment of the reactivity ratios, r_i, of both comonomers. These values were determined from the kinetics of radical copolymerization of CTFE with AGE from Fineman‐Ross, Kelen‐Tudos, and extended Kelen‐Tudos methods which led to the assessment of the average reactivity ratios as: r_CTFE = 0.20 ± 0.03 and r_AGE = 0.15 ± 0.08 at 74 °C. The lower M_n values substantiated the formation of cooligomers rather than copolymers. The formation of cooligomers was attributed to the chain transfer to AGE (by hydrogen abstraction from AGE) from the allylic transfer. The poly(CTFE‐co‐AGE) cooligomers were soluble in most of the common organic polar solvents. An optimization of cooligomer yields was investigated by using ethyl vinyl ether as a third comonomer and from different initiators. The thermal stabilities of the cooligomers, obtained by thermal gravimetric analysis, showed a 5% weight loss at temperatures over 225 °C under air. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3587–3595, 2010     

Synthesis of methallylic monomers bearing ammonium side‐groups and their radical copolymerization with chlorotrifluoroethylene

Methallylic monomers bearing triethyl or 4‐diazabicyclo[2.2.2]octane (DABCO) ammonium side‐groups are prepared and copolymerized with chlorotrifluoroethylene (CTFE). First, three different monomers are synthesized from chloro‐2‐methylprop‐1‐ene or 3‐chloro‐2‐chloromethylprop‐1‐ene in fair to good yields (57–95%). Then, several parameters (initiators, aqueous or solution processes, temperature) of the radical copolymerization of these monomers with chlorotrifluoroethylene are investigated. Various initiators are tested in the presence of ammonium perfluorooctanoate (APFO) as water‐soluble surfactant, and tert‐butyl peroxypivalate/APFO leads to the best results in a mixed solvent (H₂O/CH₃CN/C₄F₅H₅). In all experiments, the radical copolymerization shows that CTFE is more reactive than the methallylic monomer as evidenced by the characterization of poly(CTFE‐co‐M) copolymer by nuclear magnetic resonance spectroscopy and elemental analysis. Thermal degradation of these copolymers by thermogravimetric analyses indicates that the copolymers are stable up to 180 °C without any degradation and have a T_d,10% above 300 °C. Finally, their ionic exchange capacities range between 0.94 and 1.69 meq g^?1. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1721–1729     

Grafting polymerization of styrene onto alternating terpolymers based on chlorotrifluoroethylene,hexafluoropropylene, and vinyl ethers,and their modification into ionomers bearing ammonium side‐groups

The grafting polymerization of styrene initiated by the alkyl chloride groups of poly(CTFE‐alt‐VE) and poly[(CTFE‐alt‐VE)‐co‐(HFP‐alt‐VE] copolymers (where CTFE, HFP, and VE stand for chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), and vinyl ether (VE), respectively) followed by the chemical modification of the polystyrene grafts are presented. First, the fluorinated alternating copolymers were produced by radical copolymerization of CTFE (with HFP) and VE. Second, atom transfer radical polymerization enabled the grafting polymerization of styrene in the presence of the poly(CTFE‐alt‐VE)‐macroinitiator using the alkyl chloride group of CTFE as the initiation site. Kinetics of the styrene polymerization indicated that such a grafting had a certain controlled character. For the first time, grafting of polystyrene onto alternating fluorinated copolymers has been achieved. Differential scanning calorimetry thermograms of these graft copolymers exhibited two glass transition temperatures assigned to both amorphous domains of the polymeric fluorobackbone (ranging from ?20 to +56 °C) and the polystyrene grafts (ca. 95 °C). The thermostability of these copolymers increased on grafting. Thermal degradation temperatures at 5% weight loss were ranging from 193 to 305 °C when the polystyrene content varied from 81 to 27%. Third, chloromethylation of the polystyrene grafts followed by the cationization of the chloromethyl dangling groups led to original ammonium‐containing graft copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis of functional polymers bearing cyclic carbonate groups from (2-oxo-1,3-dioxolan-4-yl) methyl vinyl ether

(2-Oxo-1,3-dioxolan-4-yl) methyl vinyl ether (OVE) was synthesized with high yield by addition reaction of glycidyl vinyl ether with carbon dioxide using tetrabutylammonium bromide (TBAB) as a catalyst. OVE was also prepared by reaction with β-butyrolactone or sodium hydrogencarbonate in the presence of TBAB as the catalyst. Poly [(2-oxo-1,3-dioxolan-4-yl) methyl vinyl ether] [P(OVE)] was obtained with high yield by cationic polymerization of OVE catalyzed using boron trifluoride diethyl ether complex in dichloromethane. Polymers bearing pendant 5-membered cyclic carbonate groups were also prepared by radical copolymerization of OVE with some electron-accepting monomers. Furthermore, addition reaction of P(OVE) with alkyl amines yielded the corresponding polymer having pendant 2-hydroxyethyl carbamate residue with high conversions. © 1994 John Wiley & Sons, Inc.     

Convenient synthesis of cyclic carbonates from CO2 and epoxides by simple secondary and primary ammonium iodides as metal‐free catalysts under mild conditions and its application to synthesis of polymer bearing cyclic carbonate moiety

Hydroiodides of secondary and primary amines effectively catalyzed the reaction of carbon dioxide and epoxides under mild conditions such as ordinary pressure and ambient temperature, to obtain the corresponding five‐membered cyclic carbonates in moderate to high yields. Detailed investigation showed that the catalytic activity was highly affected by the counter anions of the ammonium salts; the iodides catalyzed efficiently the carbonate‐forming reactions, whereas the bromide and chloride counterparts exhibited almost no catalysis. We also revealed that two important factors on the amine moieties that affected the catalytic reactions. First, the catalytic activity increased with increasing bulkiness of the substituents on the ammonium nitrogen atoms. Second, the catalysis became more efficient as the parent amines become more basic. Dicyclohexylammonium iodide was the best catalyst among the ammonium salts investigated in this study. As an application of this reaction system, we synthesized homo‐ and copolymers bearing epoxide pendant groups as substrates, which were converted with high efficiency into the corresponding homo‐ and copolymers bearing cyclic carbonate pendant groups under 1 atm at 45 °C. All polymers were easily purified simply by precipitation in water, and were isolated in high yields (>95%). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis and characterization of donor–bridge–acceptor alternating copolymers containing perylene diimide units and their application to photovoltaic cells

We have used Suzuki coupling to prepare a series of alternating copolymers featuring coplanar cyclopentadithiophene and hole‐transporting carbazole units. We observed quenching in the photoluminescence spectra of our polymers after incorporating pendent electron‐deficient perylene diimide ( PDI ) moieties on the side chains, indicating more efficient photoinduced electron transfer. Electrochemical measurements revealed that the PDI ‐containing copolymers displayed reasonable and sufficient offsets of the energy levels of their lowest unoccupied molecular orbitals for efficient charge dissociation. The performance of bulk heterojunction photovoltaic cells incorporating the copolymer/[6,6]‐phenyl‐C₆₁‐butyric acid methyl ester blends (1:4, w/w) was optimized when the active layer had a thickness of 70 nm. The photocurrents of the devices were enhanced as a result of the presence of the PDI moieties, thereby leading to improved power conversion efficiencies. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1298–1309, 2010     

Synthesis and reversible hydration–dehydration system of copolymers bearing a vicinal tricarbonyl structure

Novel copolymers composed of a styrene (St) derivative bearing a vicinal tricarbonyl moiety and various vinyl monomers such as St, methyl methacrylate (MMA), and N‐vinylpyrrolidone (NVP) were synthesized by (1) radical copolymerization of a St derivative with a 1,3‐diketone structure with St, MMA, and NVP and (2) successive oxidation of the resulting copolymers with N‐bromosuccinimide in DMSO to convert their 1,3‐diketone moieties in the side chains into the corresponding vicinal tricarbonyl moieties. Their tricarbonyl moieties were readily hydrated in water‐containing acetone to generate the corresponding copolymers bearing geminal diol structures in the side chains. On the other hand, heating the resulting copolymers bearing the geminal diol structures in vacuo‐enabled successful recovery of the vicinal tricarbonyl moieties to demonstrate the reversible nature of this system. The hydration behavior in powdery state under air atmosphere saturated by water was also investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis of poly(vinylene arsine)s through the ring‐collapsed radical alternating copolymerization of an organoarsenic homocycle with aliphatic acetylenes and their properties

Poly(vinylene arsine)s with no aromatic substituent ([? CH?CR? AsMe? ]_n) were prepared through a radical alternating copolymerization of acetylenic compounds having an alkyl substituent with an organoarsenic homocycle as an arsenic‐atomic biradical equivalent. The radical reaction between 1‐octyne and pentamethylcyclopentaarsine, with a catalytic amount of 2,2′‐azobisisobutyronitrile without a solvent (60 °C, 10 h), produced the corresponding poly(vinylene arsine)s (45% yield). The copolymers obtained were soluble in tetrahydrofuran, chloroform, hexane, and so on. The copolymers were characterized with ¹H and ¹³C NMR spectra. The number‐average molecular weights of the copolymers were estimated with gel permeation chromatography (chloroform and polystyrene standards) to be 6500. The copolymers showed an emission property attributable to the n–π* transition in the main chain. Irradiation by an incandescent lamp of a mixture of 1‐octyne and 1 also produced poly(vinylene arsine)s. The conversion rate of 1‐octyne during the copolymerization with 2,2′‐azobisisobutyronitrile was measured with gas chromatography analysis and was found to be much slower than that of phenylacetylene. A radical terpolymerization of cyclo‐(AsMe)₅ with 1‐octyne and styrene was carried out to yield the terpolymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3604–3611, 2004     

Synthesis and characterization of donor–acceptor poly(3‐hexylthiophene) copolymers presenting 1,3,4‐oxadiazole units and their application to photovoltaic cells

We have used Grignard metathesis polymerization to prepare poly(3‐hexylthiophene)‐based copolymers containing electron‐withdrawing 4‐tert‐butylphenyl‐1,3,4‐oxadiazole‐phenyl moieties as side chains. We characterized these copolymers using ¹H and ¹³C nuclear magnetic resonance spectroscopy, thermogravimetric analysis, and gel permeation chromatography. The band gap energy of copolymer was determined from the onset of the optical absorption. The quenching effects were observed in the photoluminescence spectra of the copolymers incorporating pendant electron‐deficient 1,3,4‐oxadiazole moieties on the side chains. The photocurrents of devices were enhanced in the presence of an optimal amount of the 1,3,4‐oxadiazole moieties, thereby leading to improved power conversion efficiencies. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3331–3339, 2010     

Synthesis and characterization of poly(phenylacetylenes) featuring activated ester side groups

Four monomers based on 4‐ethynylbenzoic acid have been synthesized, one of those featuring an activated ester. With the metathesis catalytic system WCl₆/Ph₄Sn, these acetylenic monomers could successfully be polymerized yielding conjugated polymers with molecular weights of around 10,000 to 15,000 g/mol and molecular weight distributions M_w/M_n ≤ 2.1. Also the copolymerization of phenylacetylene or methyl 4‐ethynylbenzoate with pentafluorophenyl 4‐ethynylbenzoate as reactive unit was conducted. Polymer analogous reactions of the reactive polymers and copolymers with amines have been investigated and it was found that poly(pentafluorophenyl 4‐ethynylbenzoate) featured a significant reactivity, such that reactions proceeded quantitatively even with aromatic amines. Moreover the UV‐Vis spectra of the activated ester based polymer before and after conversion with aliphatic amines showed a change, indicating an effect on the conjugated backbone of the polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis and characterization of hyperbranched polystyrene copolymers by atom transfer radical self‐condensing vinyl copolymerization

A series of hyperbranched polystyrene copolymers were synthesized by atom transfer radical self‐condensing vinyl copolymerization (ATR‐SCVCP) of p‐chloromethylstyrene (CMS) and styrene using the complex CuCl/2,2′‐bipyridyl as catalyst. The composition and structures of these hyperbranched polystyrene copolymers were characterized by ¹H‐NMR and ¹³C‐NMR spectroscopy, gel permeation chromatography (GPC), and elemental analysis. The thermal properties were studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The influence of the reaction conditions, including comonomer ratios, reaction time, and polymerization temperature, on the molecular weight and degree of branching (DB) of the resulting copolymers were investigated in detail. With increasing ratios of styrene in total monomers from 10 to 90%, the resulting copolymers have number‐average molecular weights that change from 6.0 to 10.5 kDa, polydispersities from 2.96 to 4.74, and a degree of branching from 0.01 to 0.45. The experimental results indicated that the structures and properties can be controlled by adjusting the reaction conditions. The concentrations of styrene in the copolymers slightly affect the copolymer structures and T_g when they are less than 50 mol%, but have a large effect at greater concentrations. The results also show that the ATR‐SCVP reaction does not follow a complete ATRP feature, but has some characteristics of step‐growth polymerization. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and self‐assembly of diblock copolymers bearing 2‐nitrobenzyl photocleavable side groups

The light‐responsive behavior in solution and in thin films of block copolymers bearing 2‐nitrobenzyl photocleavable esters as side groups is discussed in this article. The polymers were synthesized by grafting 2‐nitrobenzyl moieties onto poly(acrylic acid)‐block‐polystyrene (PAA‐b‐PS) precursor polymers, leading to poly(2‐nitrobenzyl acrylate‐random‐acrylic acid)‐block‐polystyrene (P(NBA‐r‐AA)‐b‐PS) block copolymers. The UV irradiation of the block copolymers in a selective solvent for PS led to the formation of micelles that were used to trap hydrophilic molecules inside their core (light‐induced encapsulation). In addition, thin films consisting of light‐responsive P(NBA‐r‐AA) cylinders surrounded by a PS matrix were achieved by the self‐assembly of P(NBA‐r‐AA)‐b‐PS copolymers onto silicon substrates. Exposing these films to UV irradiation generates nanostructured materials containing carboxylic acids inside the cylindrical nanodomains. The availability of these chemical functions was demonstrated by reacting them with a functional fluorescent dye. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis of novel copolymers obtained from acceptor/donor radical copolymerization of phosphonated allyl monomers and maleic anhydride

A series of four phosphonated‐bearing allyl monomers, that is, diethyl‐1‐allylphosphonate ( AP ), dimethyl‐1‐allyloxymethylphosphonate ( AOP ), 5‐ethyl‐5‐(allyloxymethyl)‐2‐oxo‐1,3,2‐dioxaphosphorinane ( AEDPH ), and 2‐benzyl‐5‐ethyl‐5‐(allyloxymethyl)‐2‐oxo‐1,3,2‐dioxaphosphorinane ( AEDPBn ) were synthesized. These monomers were then copolymerized by free radical polymerization in the presence of maleic anhydride, thus leading to alternated copolymers with phosphonate moieties. It was shown that both monomer conversion and reaction rate were dependent on the phosphonate moieties carried out by the allyl monomer: the bulkier the phosphonate group, the higher the polymerization rate. Thermogravimetric analysis of the copolymers revealed a high content of residue, also varying with the nature of the phosphonate moieties. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and characterization of poly(ethylene glycol) diacrylate copolymers containing azobenzene groups prepared by frontal polymerization

A novel polymer matrix containing amino–nitro substituted azobenzene groups was obtained by frontal polymerization. (E)‐2‐(Ethyl(4‐((4‐nitrophenyl)diazenyl)phenyl)amino)ethyl methacrylate (MDR‐1) was copolymerized with poly(ethylene glycol) diacrylate (PEGDA) using this easy and fast polymerization technique. The effect of the amount of the incorporated azo‐monomer into the polymer matrix was studied in detail and correlated to front velocity, maximum temperature, initiator concentration, and monomer conversion. The obtained materials were characterized by infrared spectroscopy (Fourier transform infrared), and their thermal properties were studied by thermogravimetric analysis and differential scanning calorimetry. Moreover, the optical properties of the polymers were studied by absorption spectroscopy in the UV–Vis region. Absorption spectra of the copolymers exhibit a significant blue shift of the absorption bands with respect to the azo‐monomer, due to the presence of H‐aggregates. Cubic nonlinear optical (NLO) characterizations of the PEGDA/MDR‐1 copolymers were performed according to the Z‐Scan technique. It has been proven that samples with higher MDR‐1 content (0.75 mol %) exhibited outstandingly high NLO‐activity with negative NLO‐refractive coefficients in the promising range of n₂ = ?8.057 × 10^?4 esu. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and characterization of graft copolymers containing poly(p-phenylene) main chains and mesogen-jacketed liquid-crystalline polystyrene side chains

A series of novel comblike mesogen-jacketed liquid-crystalline graft copolymers, poly(p-phenylene)-g-poly{2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrene} (PPP-g-PMPCS) copolymers, have been designed and successfully synthesized by a Yamamoto coupling reaction and subsequent atom transfer radical polymerization (ATRP). ¹H NMR spectroscopy, ultraviolet–visible spectra, and gel permeation chromatography (GPC) have been used to confirm the molecular structure of the macroinitiator and the copolymers. A study of the polymerization kinetics of ATRP has shown that the molecular weight of the copolymer increases linearly with the conversion of the monomer, whereas the polydispersity remains narrow (≤1.28), indicating that the ATRP of 2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrene is well controlled. Thermogravimetric analysis and differential scanning calorimetry (DSC) measurements have indicated that the PPP-g-PMPCS copolymers have better thermal stabilities than the macroinitiator, and their thermal stabilities increase with increasing molecular weight. The liquid-crystalline behavior has been examined with polarized optical microscopy, DSC, one-dimensional wide-angle X-ray diffraction (1D WAXD), and two-dimensional wide-angle X-ray diffraction (2D WAXD). The results show that all the comblike copolymers exhibit obvious liquid-crystalline behaviors, even though the GPC molecular weight of the segments of poly{2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrene} (PMPCS) have been determined to be far less than the critical value of linear PMPCS. Moreover, 1D WAXD measurements show that the temperature at which the comblike mesogen-jacketed liquid-crystalline copolymers can transform into a liquid-crystalline phase is low; about 20 °C in comparison with the linear ones. 2D WAXD analysis has revealed that these comblike copolymers should be assigned to a hexatic columnar nematic (Φ_HN) phase. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2543–2555, 2007     

Synthesis and characterization of block copolymers from 2‐vinylnaphthalene by anionic polymerization

The anionic polymerization of 2‐vinylnaphthalene (2VN) has been studied in tetrahydrofuran (THF) at ?78 °C and in toluene at 40 °C. 2VN polymerization in THF, toluene, or toluene/THF (99:1 v/v) initiated by sec‐butyllithium (sBuLi) indicates living characteristics, affording polymers with predefined molecular weights and narrow molecular weight distributions. Block copolymers of 2VN with methyl methacrylate (MMA) and tert‐butyl acrylate (tBA) have been synthesized successfully by sequential monomer addition in THF at ?78 °C initiated by an adduct of sBuLi–LiCl. The crossover propagation from poly(2‐vinylnaphthyllithium) (P2VN) macroanions to MMA and tBA appears to be living, the molecular weight and composition can be predicted, and the molecular weight distribution of the resulting block copolymer is narrow (weight‐average molecular/number‐average molecular weight < 1.3). Block copolymers with different chain lengths for the P2VN segment can easily be prepared by variations in the monomer ratios. The block copolymerization of 2VN with hexamethylcyclotrisiloxane also results in a block copolymer of P2VN and poly(dimethylsiloxane) (PDMS) contaminated with a significant amount of homo‐PDMS. Poly(2VN‐b‐nBA) (where nBA is n‐butyl acrylate) has also been prepared by the transesterification reaction of the poly(2VN‐b‐tBA) block copolymer. Size exclusion chromatography, Fourier transform infrared, and ¹H NMR measurements indicate that the resulting polymers have the required architecture. The corresponding amphiphilic block copolymer of poly(2VN‐b‐AA) (where AA is acrylic acid) has been synthesized by acidic hydrolysis of the ester group of tert‐butyl from the poly(2VN‐b‐tBA) copolymer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4387–4397, 2002     

Synthesis and characterization of side-chain liquid-crystalline poly(ether ester)s having p-substituted biphenyl mesogenic side groups

Several novel mesogenic spiro-orthoester monomers such as 1,6,10-trioxaspiro[4,5]decanes 4 , containing biphenyl mesogens at the C-8 positions of the five- and six-membered spirocyclic ring, through the alkylene spacers of different lengths were prepared by condensation reaction of the corresponding biphenyl mesogenic 1,3-propanediol 3 with 2,2-diethoxytetrahydrofuran, with 50–75% yields. Through cationic double ring-opening polymerization, carried out with boron trifluoride etherate as an initiator (5 mol % vs. monomer) in bulk at 150°C, spiro-orthoester monomers 4 afforded a novel class of side-chain thermotropic LC polymers with a poly(ether ester) as the main chain 8 . The liquid-crystalline properties of the spiro-orthoester monomers and the resulting polymers were examined by differential scanning calorimetry and optical polarized microscopy. Biphase separation was observed in the side-chain liquid-crystalline poly(ether ester)s upon annealing in the broad isotropic region. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2439–2455, 1998     

Synthesis and characterization of fluorinated telomers containing vinylidene fluoride and hexafluoropropene from 1,6‐diiodoperfluorohexane

The synthesis of original fluorinated (co)telomers containing vinylidene fluoride (VDF) or VDF and hexafluoropropene (HFP) was achieved by radical telomerizations and (co)telomerizations of VDF (or VDF and HFP) in the presence of 1, 6‐diiodoperfluorohexane via a semisuspension process. tert‐Butyl peroxypivalate (TBPPi) was used as an efficient thermal initiator. The numbers of VDF and VDF/HFP base units in the (co)telomers were determined by ¹⁹F and ¹H NMR spectroscopy. They ranged from 10 to 190 VDF base units. Fluorinated telomers of various molecular weights (1200–12,600 g/mol) were obtained by the alteration of the initial [1,6‐diiodoperfluorohexane]₀/[fluoroalkenes]₀ and [TBPPi]₀/[fluoroalkenes]₀ molar ratios. The thermal properties of these fluorinated (co)telomers, such as the glass‐transition temperature and melting temperature, were examined. As expected, these telomers exhibited good thermal stability. They were stable at least up to 350 °C. The compounds containing more than 30 VDF units were crystalline, whereas all those containing VDF‐co‐HFP were amorphous with elastomeric properties, whatever the number was of the fluorinated base units. The structures of I–(VDF)_n–R_F–(VDF)_m–I and I–(HFP)_x(VDF)_n–R_F–(VDF)_m(HFP)_y–I (co)telomers were obtained, and the defects of the VDF chain and the ? CH₂CF₂I and ? CF₂CH₂I functionalities were studied successfully (where R_F = C₆F₁₂). The functionality in the iodine atoms was modified: the higher the VDF content in the telomers, the lower the normal end functionality (? CH₂CF₂I) and the higher the reversed extremity (? CF₂CH₂I). In addition, the percentage of defects increased when the number of VDF units increased. The molecular weights and molecular weight distributions of different telomers and cotelomers were also studied. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1470–1485, 2006