Fluorinated block copolymers containing poly(vinylidene fluoride) or poly(vinylidene fluoride‐co‐hexafluoropropylene) blocks from perfluoropolyethers: Synthesis and thermal properties

PFPE‐b‐PVDF and PFPE‐b‐poly(VDF‐co‐HFP) block copolymers [where PFPE, PVDF, VDF, and HFP represent perfluoropolyether, poly(vinylidene fluoride), vinylidene fluoride (or 1,1‐difluoroethylene), and hexafluoropropylene] were synthesized by radical (co)telomerizations of VDF (or VDF and HFP) with an iodine‐terminated perfluoropolyether (PFPE‐I). Di‐tert‐butyl peroxide (DTBP) was used and was shown to act as an efficient thermal initiator. The numbers of VDF and VDF/HFP base units in the block copolymers were assessed with ¹⁹F NMR spectroscopy. According to the initial [PFPE‐I]₀/[fluoroalkenes]₀ and [DTBP]₀/[fluoroalkenes]₀ molar ratios, fluorinated block copolymers of various molecular weights (1500–30,300) were obtained. The states and thermal properties of these fluorocopolymers were investigated. The compounds containing PVDF blocks with more than 30 VDF units were crystalline, whereas all those containing poly(VDF‐co‐HFP) blocks exhibited amorphous states, whatever the numbers were of the fluorinated base units. All the samples showed negative glass‐transition temperatures higher than that of the starting PFPE. Interestingly, these PFPE‐b‐PVDF and PFPE‐b‐poly(VDF‐co‐HFP) block copolymers exhibited good thermostability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 160–171, 2003     

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     

Synthesis of original para‐sulfonic acid aminoethylthioethylbenzenesulfonic by telomerization,and its grafting onto poly(VDF‐co‐HFP) copolymers for proton exchange membrane for fuel cell

The synthesis of a novel aromatic sulfonic acid bearing an amino function H₂N? C₂H₄? S? C₂H₄? C₆H₄? SO₃Na ( 1 ) from the radical addition of mercaptoethylamine hydrochloride onto styrene sodium sulfonate, and its subsequent grafting onto poly(vinylidene fluoride‐co‐hexafluoropropylene), poly(VDF‐co‐HFP), copolymer are presented. First, the radical telomerization, carried out under radical conditions and in water, led to various products [monoadduct ( 1 ), multiadducts, and polymers], the amounts of which depend on the experimental conditions and [mercaptan]₀/[monomer]₀ initial molar ratio (R₀). An R₀ ≥ 1 led to the monoadduct ( 1 ) only and achieved in ～85% yield. The zwitterionic isomer was obtained mainly and its chemical modification was possible to get an original aromatic sodium sulfonate containing an amino end group. A kinetic study of the telomerization was presented for R₀ < 1. Thermogravimetric analysis of the telomer showed that this compound was stable up to 200 °C. Second, the grafting of ( 1 ) onto poly(VDF‐co‐HFP) copolymer was also investigated. Such a grafting proceeded as expected by a classic mechanism of grafting of amines. Molar percentages of grafted telomer were assessed by ¹H NMR spectroscopy and by elemental analysis. Ion exchange capacity (IEC) values of the membranes were deduced from the mol % grafted telomer. Scanning electron microscopy pictures showed a good homogeneity in the cross‐section of membranes, and energy dispersive X‐ray evidenced that all SO₃Na groups of the grafted amine were changed into SO₃H after treatment with concentrated HCl. Method involving an impedance analyzer, working at increasing high frequencies was used to assess the protonic conductivities, σ. These values were lower than that of Nafion117^®, but σ increased with the IEC to 0.4 mS/cm at room temperature and 95% relative humidity. Water and methanol uptakes were also assessed, and it was shown that σ increased when water uptakes increased. Membranes started to decompose from 170 °C under air. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 121–136, 2009     

Interphase/interface modification on the dielectric properties of polycarbonate/poly(vinylidene fluoride‐co‐hexafluoropropylene) multilayer films for high‐energy density capacitors

Unique three‐component multilayer films with ATBTATBTA configuration were fabricated using forced assembly multilayer coextrusion for novel dielectric systems. The dielectric breakdown strength, displacement–electric field hysteresis, and dielectric spectroscopy of 65‐layer polycarbonate (PC)/tie/poly(vinylidene fluoride‐co‐hexafluoropropylene) (P(VDF‐HFP)) were investigated with various tie materials. Three different tie materials, poly(methyl methacrylate) (PMMA), styrene‐co‐acrylonitrile copolymer with 30% acrylonitrile content (SAN30), and poly(ethylene terephthalate‐co‐1,4‐cycohexanedimethylene terephthalate) (PETG) were chosen owing to their various degrees of interaction with either P(VDF‐HFP) or PC. The 65‐layer PC/PMMA/P(VDF‐HFP) films exhibited a 25% enhancement in breakdown properties, 50% higher energy density, 40% smaller hysteresis loop areas, and orders of magnitude slower ion migration relative to the 33‐layer PC/P(VDF‐HFP) control. These property improvements are mainly attributed to the localized interactions at PMMA/P(VDF‐HFP) and PMMA/PC interfaces, forming interphase regions. The modified PMMA/P(VDF‐HFP) interphase region can effectively hinder the migration of impurity ions in P(VDF‐HFP), reducing their mobility within the layer. Additionally, a small fraction of PMMA can lead to slightly increased dielectric constant of the composite films owing to strong interaction between PMMA and P(VDF‐HFP). The other two systems with PETG and SAN30 as tie layers exhibited marginal improvements in dielectric properties owing to their weaker interactions with the P(VDF‐HFP) layers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 978–991     

Crystal‐structure dependence of electroactive properties in differently prepared poly(vinylidene fluoride/hexafluoropropylene) copolymer films

The electroactive properties of two random copolymers of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) were studied. The compositions were 95/5 and 85/15 mol % P(VDF/HFP). For each composition, three different film‐preparation methods were used—solvent casting, melt‐pressed quenched, and melt‐pressed slow‐cooled. The ferroelectric properties observed were strongly dependent on the preparation methods of the films as well as the HFP molar content of the samples. The highest remanent polarizations (P_r) obtained from electric displacement versus electric field (D‐E) hysteresis data are 80 and 50 mC/m² for the 5 and 15% HFP solvent‐cast samples, respectively. The slow‐cooled samples do not exhibit any ferroelectric behavior for either the 5 or 15% HFP copolymers. It was also observed that both the 5 and 15% HFP slow‐cooled samples have a smaller electrostrictive response relative to the other two types of samples. Wide‐angle X‐ray diffraction and DSC results suggest that the 5% HFP sample has a higher crystallinity relative to the 15% HFP sample for each preparation method. In addition, different crystal phases form in the samples resulting from the different preparation methods. Fourier transform infrared results suggest that the slow‐cooled samples are in the nonpolar α phase, whereas the quenched and solvent‐cast samples are more likely in the polar β phase. The slow‐cooled samples do not show a switching peak in their nonpolar α‐phase crystalline state. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2793–2799, 2001     

Preparation of densely grafted poly(aniline‐2‐sulfonic acid‐co‐aniline)s as novel water‐soluble conducting copolymers

Various densely grafted polymers containing poly(aniline‐2‐sulfonic acid‐co‐aniline)s as side chains and polystyrene as the backbone were prepared. A styryl‐substituted aniline macromonomer, 4‐(4‐vinylbenzoxyl)(N‐tert‐butoxycarbonyl)phenylamine (4‐VBPA‐^tBOC), was first prepared by the reaction of 4‐aminophenol with the amino‐protecting moiety di‐tert‐butoxyldicarbonate, and this was followed by substitution with 4‐vinylbenzyl chloride. 4‐VBPA‐^tBOC thus obtained was homopolymerized with azobisisobutyronitrile as an initiator, and this was followed by deprotection with trifluoroacetic acid to generate poly[4‐(4‐vinylbenzoxyl)phenylamine] (PVBPA) with pendent amine moieties. Second, the copolymerization of aniline‐2‐sulfonic acid and aniline was carried out in the presence of PVBPA to generate densely grafted poly(aniline‐2‐sulfonic acid‐co‐aniline). Through the variation of the molar feed ratio of aniline‐2‐sulfonic acid to aniline, various densely grafted copolymers were generated with different aniline‐2‐sulfonic acid/aniline composition ratios along the side chains. The copolymers prepared with molar feed ratios greater than 1/2 were water‐soluble and had conductivities comparable to those of the linear copolymers. Furthermore, these copolymers could self‐dope in water through intermolecular or intramolecular interactions between the sulfonic acid moieties and imine nitrogens, and this generated large aggregates. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1090–1099, 2005     

Synthesis of functional polymers—Vinylidene fluoride based fluorinated copolymers and terpolymers bearing bromoaromatic side‐group

The radical co‐ and terpolymerization of 4‐[(α,β,β‐trifluorovinyl)oxy]bromo benzene (TFVOBB) with 1,1‐difluoroethylene (or vinylidene fluoride, VDF, or VF₂), hexafluoropropene (HFP), perfluoromethyl vinyl ether (PMVE), and chlorotrifluroroethylene (CTFE) is presented. Although TFVOBB could be thermocyclodimerized, it could not homopolymerize under radical initiation. TFVOBB could be copolymerized in solution under a radical initiator with VDF or CTFE comonomers, while its copolymerization with HFP or PMVE were unsuccessful. The terpolymerization of TFVOBB with VDF and HFP, or VDF and PMVE, or VDF and CTFE also led to original fluorinated terpolymers bearing bromoaromatic side‐groups. The conditions of co‐ and terpolymerization were optimized in terms of the nature of the radical initiators, and of the nature of solvents (fluorinated or nonhalogenated). Various monomer concentrations in the co‐ and terpolymers were assessed by ¹⁹F and ¹H‐NMR spectroscopy. The thermal and physico chemical properties were also studied. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5077–5097, 2004     

Grafting of polymers onto a carbon‐fiber surface by ligand‐exchange reaction of poly(vinyl ferrocene‐co‐vinyl monomer) with polycondensed aromatic rings of the surface

To improve the surface of carbon fiber, the grafting reaction of copolymer containing vinyl ferrocene (VFE) onto a carbon‐fiber surface by a ligand‐exchange reaction between ferrocene moieties of the copolymer and polycondensed aromatic rings of carbon fiber was investigated. The copolymer containing VFE was prepared by the radical copolymerization of VFE with vinyl monomers, such as methyl methacrylate (MMA) and styrene, using 2,2′‐azobisisobutyronitrile as an initiator. By heating the carbon fiber with poly(VFE‐co‐MMA) (number‐average molecular weight: 2.1 × 10⁴) in the presence of aluminum chloride and aluminum powder, the copolymer was grafted onto the surface. The percentage of grafting reached 46.1%. On the contrary, in the absence of aluminum chloride, no grafting of the copolymer was observed. Therefore, it is considered that the copolymer was grafted onto the carbon‐fiber surface by a ligand‐exchange reaction between ferrocene moieties of the copolymer and polycondensed aromatic rings of carbon fiber. The molar number of grafted polymer chain on the carbon‐fiber surface decreased with increasing molecular weight of poly(VFE‐co‐MMA) because the steric hindrance of grafted copolymer on the carbon‐fiber surface increases with increasing molecular weight of poly(VFE‐co‐MMA). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1868–1875, 2002     

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

The 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: r_VDF = 0.57 ± 0.15 and r_PFSVE = 0.07 ± 0.04 at 120 °C. The thermal and physicochemical properties were also studied. Moreover, the glass transition temperatures (T_gs) of poly(VDF‐co‐PFSVE) copolymers containing different amounts of VDF and PFSVE were determined and the theoretical T_g 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     

Radical copolymerization of vinylidene fluoride with 1‐bromo‐2,2‐difluoroethylene

The radical copolymerization of vinylidene fluoride (VDF) and 1‐bromo‐2,2‐difluoroethylene (BDFE) in 1,1,1,3,3‐pentafluorobutane solution at different monomer molar ratios (ranging from 96/4 to 25/75 mol %) and initiated by tert‐butylperoxypivalate (TBPPI, mainly) is presented. Poly(VDF‐co‐BDFE) copolymers of various aspects (from white powders to yellow viscous liquids) were produced depending on the copolymer compositions. The microstructures of the obtained copolymers were characterized by ¹⁹F and ¹H NMR spectroscopy and by elementary analysis and these techniques enabled one to assess the contents of both comonomers in the produced copolymers. VDF was shown to be more incorporated in the copolymer than BDFE. From the extended Kelen and Tudos method, the kinetics of the radical copolymerization led to the determination of the reactivity ratios, r_i, of both comonomers (r_VDF = 1.20 ± 0.50 and r_{BDFE =} 0.40 ± 0.15 at 75 °C) showing that VDF is more reactive than BDFE. Alfrey‐Price's Q and e values of BDFE monomer were calculated to be 0.009 (from Q_VDF = 0.008) or 0.019 (from Q_VDF = 0.015) and +1.22 (vs. e_VDF = 0.40) or +1.37 (vs. e_VDF = 0.50), respectively, indicating that BDFE is an electron‐accepting monomer. Statistic cooligomers were produced with molar masses ranging from 1,800 to 5,500 g/mol (assessed by GPC with polystyrene standards). A further evidence of the successful copolymerization was shown by the selective reduction of bromine atoms in poly(VDF‐co‐BDFE) cooligomers that led to analog PVDF. The thermal properties of the poly(VDF‐co‐BDFE) cooligomers were also determined and those containing a high VDF amount exhibited a high thermal stability. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3964–3976, 2010.     

Iridium‐Catalyzed Regioselective Silylation of Aromatic and Benzylic CH Bonds Directed by a Secondary Amine

Reported herein is an iridium‐catalyzed, regioselective silylation of the aromatic C? H bonds of benzylamines and the benzylic C? H bonds of 2,N‐dialkylanilines. In this process, (hydrido)silyl amines, generated in situ by dehydrogenative coupling of benzylamine or aniline with diethylsilane, undergo selective silylation at the C? H bond γ to the amino group. The products of this silylation are suitable for subsequent oxidation, halogenation, and cross‐coupling reactions to deliver benzylamine and arylamine derivatives.     

Polymers from renewable resources. II. A study in the radio chemical grafting of poly(styrene‐alt‐maleic anhydride) onto cellulose extracted from pine needles

A binary mixture of styrene and maleic anhydride has been graft copolymerized onto cellulose extracted from Pinus roxburghii needles. The reaction was initiated with gamma rays in air by the simultaneous irradiation method. Graft copolymerization was studied under optimum conditions of total dose of radiation, amount of water, and molar concentration previously worked out for grafting styrene onto cellulose. Percentage of total conversion (Pg), grafting efficiency (%), percentage of grafting (Pg), and rates of polymerization (R_p), grafting (R_g), and homopolymerization (R_h) have been determined as a function of maleic anhydride concentration. The high degree of kinetic regularity and the linear dependence of the rate of polymerization on maleic anhydride concentration, along with the low and nearly constant rate of homopolymerization suggest that the monomers first form a complexomer which then polymerizes to form grafted chains with an alternating sequence. Grafting parameters and reaction rates achieve maximum values when the molar ratio of styrene to maleic anhydride is 1 : 1. Further evidence for the alternating monomer sequence is obtained from quantitatively evaluating the composition of the grafted chains from the FT‐IR spectra, in which the ratio of anhydride absorbance to aromatic (CC) absorbance for the stretching bands assigned to the grafted monomers remained constant and independent of the feed ratio of maleic anhydride to styrene. Thermal behaviour of the graft copolymers revealed that all graft copolymers exhibit single stage decomposition with characteristic transitions at 161–165°C and 290–300°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1763–1769, 1999     

Templated synthesis of silver nanoparticles in amphiphilic poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) comb copolymer

In this study, poly(vinylidene fluoride‐co‐chlorotrifluoroethylene)‐graft‐poly(oxyethylene methacrylate), P(VDF‐co‐CTFE)‐g‐POEM, an amphiphilic comb copolymer with hydrophobic P(VDF‐co‐CTFE) backbone and hydrophilic POEM side chains at 73:27 wt % was synthesized. The POEM side chains were grafted from the P(VDF‐co‐CTFE) mainchain backbone via atom transfer radical polymerization (ATRP) using direct initiation of the chlorine atoms in CTFE units. Synthesis of microphase‐separated P(VDF‐co‐CTFE)‐g‐POEM comb copolymer was successful, as confirmed by nuclear magnetic resonance (¹H NMR), FTIR spectroscopy, and transmission electron microscopy (TEM). Nanocomposite films were prepared using the comb copolymer as a template film and the in situ reduction of AgCF₃SO₃ precursor to silver nanoparticles under UV irradiation. Silver nanoparticles with 4–8 nm in average size were in situ created in the solid state template film, as revealed by TEM, UV–visible spectroscopy, and wide angle X‐ray scattering (WAXS). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) presented the selective incorporation and the in situ growth of silver nanoparticles within the hydrophilic POEM domains of microphase‐separated comb copolymer film. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 702–709, 2008     

Correlations between microstructure and crystallization of the fluorinated terpolymer of tetrafluoroethylene,hexafluoropropylene, and vinylidene fluoride

Random THV terpolymers consisting of tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and vinylidene fluoride (VDF) are viable alternatives to polytetrafluoroethylene (PTFE) combining excellent chemical stability and thermoplastic processability. Although the properties of THV may be modified by crystallization, little is known on how crystallization is influenced by the chain microstructure of THV. We analyzed the chain microstructure of THV‐221G by solid‐state ¹⁹F NMR spectroscopy under fast magic angle spinning, revealing that THV‐221G contains 43.8 mol % TFE, 46.0 mol % VDF, and 10.2 mol % HFP. Sequence analysis revealed that the TFE units are preferentially located next to other TFE units. The HFP units, which are obstacles to crystallization because of their bulky CF₃ side groups, are preferentially located next to VDF units. WAXS measurements correspondingly revealed the presence of THV‐221G crystals with PTFE‐like packing and of further THV‐221G crystal populations with widened d‐spacings caused by the incorporation of certain amounts of HFP units into the THV‐221G crystals. Under confinement imposed by the cylindrical nanopores of self‐ordered alumina, the THV‐221G melting point decreased with decreasing pore diameter. Although direct impingement of the growing THV‐221G crystals on the pore walls is unlikely, the geometric confinement limits the access of growing THV‐221G crystals to crystallizable THV‐221G chain segments. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 1402–1408     

SEC with UV and ELSD detection for analysis of gamma-irradiated PS-radiation-grafted P(VDF/HFP) films

Summary Thin poly(vinylidene fluoride/hexafluoropropylene) (P(VDF/HFP)) films ahve been irradiated with gammarays to induce the initiation of styrene grafting by the indirect method. To obtain a better understanding of the radiation-grafting process we have used size exclusion chromatography (SEC) to study the effect of irradiation of this polymer and the evolution of the molecular weights of the polystyrene (PS) grafted chains as a function of the grafting time. Pristine, irradiated and PS radiation-grafted samples have been compared. We present evidence that the gamma irradiation induces both scission and crosslinking of the P(VDF/HFP) chains. We show that the average molecular weights of the PS grafted chains increase with grafting time and that the asymmetry of the chromatographic peak increases also. These grafted chains have molecular weights much higher than those of pristine P(VDF/HFP) and they cannot be confused with PS homopolymer chains, which have higher molecular weights as both, pristine and radiation-grafted P (VDF/HFP). Reversed-phase high-performance liquid chromatography (RPHPLC) has shown the absence of additives in pristine P(VDF/HFP) and has provided evidence of the presence of oligomers.     

Grafting of poly(ε‐caprolactone) onto maghemite nanoparticles

We report the coating of maghemite (γ‐Fe₂O₃) nanoparticles with poly(ε‐caprolactone) (PCL) through a covalent grafting to technique. ω‐Hydroxy‐PCL was first synthesized by the ring‐opening polymerization of ε‐caprolactone with aluminum isopropoxide and benzyl alcohol as a catalytic system. The hydroxy end groups of PCL were then derivatized with 3‐isocyanatopropyltriethoxysilane in the presence of tetraoctyltin. The triethoxysilane‐functionalized PCL macromolecules were finally allowed to react on the surface of maghemite nanoparticles. The composite nanoparticles were characterized by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Effects of the polymer molar mass and concentration on the amount of polymer grafted to the surface were investigated. Typical grafting densities up to 3 μmol of polymer chains per m² of maghemite surface were obtained with this grafting to technique. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6011–6020, 2004     

Dispersion of silica nanoparticles bearing perfluorohexyl units into fluorinated copolymers

This study aims at determining the compatibility behavior of nanoparticles surface with fluorinated matrices to obtain a homogenous dispersion and better composites properties. First, modified silica nanoparticles by C₆F₁₃I and C₆F₁₃‐C₂H₄‐SH led to various fluorinated silica of different massic concentrations and grafting rates. The dispersion of these nanoparticles (in 5 wt %) into molten poly(VDF‐co‐HFP) and poly(TFE‐co‐HFP) matrices were studied as well as the hydrophobic, mechanical, and thermal properties of both fluorinated copolymers and resulting composites. In both series, the storage modulus of nanocomposites increased while the melting (T_m) and decomposition (T_10%) temperatures varied with the polymer matrix. They increased for poly(VDF‐co‐HFP) composites (T_m= 134 to 144 °C and T_10%= 441 to 464 °C) but decreased for poly(TFE‐co‐HFP) nanocomposites (T_m= 276 to 268 °C and T_10%= 488 to 477 °C). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1512–1522     

Synthesis of poly(vinylidene fluoride)‐b‐poly(styrene sulfonate) block copolymers by controlled radical polymerizations

Block copolymers based on poly(vinylidene fluoride), PVDF, and a series of poly(aromatic sulfonate) sequences were synthesized from controlled radical polymerizations (CRPs). According to the aromatic monomers, appropriate techniques of CRP were chosen: either iodine transfer polymerization (ITP) or atom transfer radical polymerization (ATRP) from PVDF‐I macromolecular chain transfer agents (CTAs) or PVDF‐CCl₃ macroinitiator, respectively. These precursors were produced either by ITP of VDF with C₆F₁₃I or by radical telomerization of VDF with chloroform, respectively. Poly(vinylidene fluoride)‐b‐poly(sodium styrene sulfonate), PVDF‐b‐PSSS, block copolymers were produced from both techniques via a direct polymerization of sodium styrene sulfonate (SSS) monomer or an indirect way with the use of styrene sulfonate ethyl ester (SSE) as a protected monomer. Although the reaction led to block copolymers, the kinetics of ITP of SSS showed that PVDF‐I macromolecular CTAs were not totally efficient because a limitation of the CTA consumption (56%) was observed. This was probably explained by both the low activity of the CTA (that contained inefficient PVDF‐CF₂CH₂? I) and a fast propagation rate of the monomer. That behavior was also noted in the ITP of SSE. On the other hand, ATRP of SSS initiated by PVDF‐CCl₃ was more controlled up to 50% of conversion leading to PVDF‐b‐PSSS block copolymer with an average number molar mass of 6000 g·mol^?1. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Nanofiltration membranes based on poly(vinylidene fluoride‐co‐chlorotrifluoroethylene)‐graft‐poly(styrene sulfonic acid)

Graft copolymers comprising poly(vinylidene fluoride‐co‐chlorotrifluoroethylene) backbone and poly(styrene sulfonic acid) side chains, i.e. P(VDF‐co‐CTFE)‐g‐PSSA were synthesized using atom transfer radical polymerization (ATRP) for composite nanofiltration (NF) membranes. Direct initiation of the secondary chlorinated site of CTFE units facilitates grafting of PSSA, as revealed by FT‐IR spectroscopy. The successful “grafting from” method and the microphase‐separated structure of the graft copolymer were confirmed by transmission electron microscopy (TEM). Wide angle X‐ray scattering (WAXS) also showed the decrease in the crystallinity of P(VDF‐co‐CTFE) upon graft copolymerization. Composite NF membranes were prepared from P(VDF‐co‐CTFE)‐g‐PSSA as a top layer coated onto P(VDF‐co‐CTFE) ultrafiltration support membrane. Both the rejections and the flux of composite membranes increased with increasing PSSA concentration due to the increase in SO₃H groups and membrane hydrophilicity, as supported by contact angle measurement. The rejections of NF membranes containing 47 wt% of PSSA were 83% for Na₂SO₄ and 28% for NaCl, and the solution flux were 18 and 32 L/m² hr, respectively, at 0.3 MPa pressure. Copyright © 2008 John Wiley & Sons, Ltd.     

Biosensing of Aromatic Amines in Reversed Micelles with Self‐Generation of Hydrogen Peroxide at Glucose Oxidase‐Peroxidase Bienzyme Electrodes

The amperometric biosensing of aromatic amines using a composite glucose oxidase (GOD)‐peroxidase (HRP) biosensor in reversed micelles is reported. Rigid composite pellets of graphite and Teflon, in which GOD and HRP were coimmobilized by simple physical inclusion, were employed for the biosensor design. This design allows the in situ generation of the H₂O₂ needed for the enzyme reaction with the aromatic amines, thus preventing the negative effect that the presence of a high H₂O₂ concentration in solution has on HRP activity. The H₂O₂ in situ generation is performed by oxidation of glucose catalyzed by GOD. The effect of the composition of the reversed micelles, i.e., the nature of the organic solvent used as the continuous phase, the nature and concentration of the surfactant used as emulsifying agent, the aqueous 0.05 mol L^?1 phosphate buffer percentage used as the dispersed phase, and the glucose concentration in the aqueous phase, on the biosensor response was evaluated. Reversed micelles formed with ethyl acetate, a 5% of phosphate buffer (pH 7.0) containing 3.0×10^?3 mol L^?1 glucose, and 0.1 mol L^?1 AOT (sodium dioctylsulfosuccinate), were selected as working medium. Well‐defined and reproducible amperometric signals at 0.00 V were obtained for p‐phenylenediamine, 2‐aminophenol, o‐phenylenediamine, m‐phenylenediamine, 1‐naphthylamine, o‐toluidine and aniline. The useful lifetime of one single biosensor was of 60 days. The trend in sensitivity observed for the aromatic amines is discussed considering the effect of their structure on the stabilization of the radicals formed in the enzyme reaction which are electrochemically reduced. The behavior of the composite bienzyme electrode was also evaluated in a FI (flow injection) system using reversed micelles as the carrier. The suitability of the composite bienzyme electrode for the analysis of real samples was demonstrated by determining aniline in spiked carrots.