Synthesis of unsaturation containing P(VDF‐co‐TrFE‐co‐CTFE) from P(VDF‐co‐CTFE) in one‐pot catalyzed with Cu(0)‐based single electron transfer living radical polymerization system

Poly(vinylidene fluoride‐co‐trifluoroethylene‐co‐chlorotrifluoroethylene) (P(VDF‐co‐TrFE‐co‐CTFE)) with internal double bond has been reported with high dielectric constant and energy density at room temperature, which is expected to serve as a promising dielectric film in high pulse discharge capacitors. An environmentally friendly one‐pot route, including the controllable hydrogenation via Cu(0) mediated single electron transfer radical chain transfer reaction (SET‐CTR) and dehydrochlorination catalyzed with N‐containing reagent, is successfully developed to synthesize P(VDF‐co‐TrFE‐co‐CTFE) containing unsaturation. The resultant polymer was carefully characterized with ¹H NMR, ¹⁹F NMR, and FTIR. The composition of the resultant copolymer is strongly influenced by reaction conditions, including the reaction temperature, catalyst concentration, the types of ligands and solvents. The kinetics data of the chain transfer and elimination reaction demonstrate their well‐controlled feature of the strategy. By shifting the equilibrium between the CTR and elimination reactions dominated by N‐compounds serving as ligands in SET‐CTR and catalyst in the dehydrochlorination of P(VDF‐co‐CTFE), P(VDF‐co‐TrFE‐co‐CTFE) with tunable TrFE and double‐bond content could be synthesized in this one‐pot route. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3429–3440     

Evaluation of piezoelectric poly(vinylidene fluoride) polymers for use in space environments. I. Temperature limitations

Smart materials, such as thin‐film piezoelectric polymers, are interesting for potential applications on Gossamer spacecraft. This investigation aims to predict the performance and long‐term stability of the piezoelectric properties of poly(vinylidene fluoride) (PVDF) and its copolymers under conditions simulating the low‐Earth‐orbit environment. To examine the effects of temperature on the piezoelectric properties of PVDF, poly(vinylidenefluoride‐co‐trifluoroethylene), and poly(vinylidenefluoride‐co‐hexafluoropropylene), the d₃₃ piezoelectric coefficients were measured up to 160 °C, and the electric displacement/electric field (D–E) hysteresis loops were measured from ?80 to +110 °C. The room‐temperature d₃₃ coefficient of PVDF homopolymer films, annealed at 50, 80, and 125 °C, dropped rapidly within a few days of thermal exposure and then remained unchanged. In contrast, the TrFE copolymer exhibited greater thermal stability than the homopolymer, with d₃₃ remaining almost unchanged up to 125 °C. The HFP copolymer exhibited poor retention of d₃₃ at temperatures above 80 °C. In situ D–E loop measurements from ?80 to +110 °C showed that the remanent polarization of the TrFE copolymer was more stable than that of the PVDF homopolymer. D–E hysteresis loop and d₃₃ results were also compared with the deflection of the PVDF homopolymer and TrFE copolymer bimorphs tested over a wide temperature range. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1310‐1320, 2005     

High‐resolution solid‐state NMR study of the domain structure and molecular motion in drawn films of a vinylidene fluoride and trifluoroethylene copolymer with 73 mol % vinylidene fluoride

The heterogeneous higher order structure and molecular motion in a single crystalline film of a vinylidene fluoride (VDF) and trifluoroethylene (TrFE) copolymer with 73 mol % VDF was investigated with the ¹H–¹³C cross‐polarization/magic‐angle spinning NMR technique. A transient oscillation was observed in plots of the ¹³C peak intensity versus the contact time for the CH₂, CHF, and CF₂ groups. On the basis of the extended cross‐relaxation theory of spin diffusion, we determined that the oscillation behavior was caused by the TrFE‐rich segments in the chain and that the crystal consisted of VDF‐rich and TrFE‐rich domains. The former had TrFE‐rich segments in VDF and TrFE fractions of 0.24 and 0.27, respectively, and the latter had VDF‐rich segments in a VDF fraction of 0.49. The spin–lattice relaxation time T_1ρH in the rotating frame for each group was minimal in the three temperature regions of β, α_b, and α_c (↑) on heating and in the two temperature regions of α_1D and α_c (↓) on cooling. The α_c (↑) and α_c (↓) processes depended on the first‐order ferroelectric phase‐transition regions on heating and cooling, respectively. The motional modes for the other processes were confirmed by the T_1ρH minimum behavior of the VDF and TrFE groups in the TrFE‐rich domain and the VDF‐rich segments in the VDF‐rich domain. The β and α_b processes were attributed to the flip–flop motion of the TrFE‐rich segments and the competitive motion of the TrFE‐ and VDF‐rich segments in the ferroelectric phase, respectively. The α_1D process was due to the one‐dimensional diffusion motion of the conformational defects along the chain in the paraelectric phase, accompanied by the trans and gauche transformation of the VDF conformers of ttg⁺tg^? and g⁺tg^?tt. The effect of the competitive motion of the TrFE‐rich segment on the thermal stability of the VDF‐rich segment in the chain near the Curie temperature was examined. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1026–1037, 2002     

Miscibility and ferroelectric behavior in blends of poly(vinylidene fluoride/trifluoroethylene) and poly(vinyl acetate)

The blend system containing a poly(vinylidene fluoride/trifluoroethylene) [P(VDF/TrFE)] copolymer (68/32 mol %) and poly(vinyl acetate) (PVAc) was miscible from the results of differential scanning calorimetry (DSC) studies that exhibit the presence of a single, composition‐dependent glass transition temperature (T_g) and a strong melting point depression for the semicrystalline P(VDF/TrFE) component. However, differences between the DSC and dielectric measurements, which showed a separate P(VDF/TrFE) T_g peak, suggests that the P(VDF/TrFE)/PVAc blends are actually partially miscible. Because of the lower dielectric constant of PVAc and the reduced sample crystallinity caused by the addition of PVAc, both the dielectric constant and the remanent polarization of the copolymer blends decrease with increasing PVAc content. The presence of a small amount of PVAc stabilized the anomalous ferroelectric behavior of ice–water‐quenched P(VDF/TrFE), and the blend portrayed normal polarization reversal behavior after adding only 1 wt % PVAc. The piezoelectric response suggests small changes with an increasing number of poling cycles. It is believed that PVAc affects the D‐E hysteresis behavior at the interface between crystalline and amorphous phases, although much work remains to be done to confirm this hypothesis. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 927–935, 2003     

Poling influence on the mechanical properties and molecular mobility of highly piezoelectric P(VDF‐TrFE) copolymer

The calorimetric, dielectric, and mechanical responses of highly piezoelectric 70/30 P(VDF‐TrFE) displaying homogenous d₃₃ of ?19 pC N^?1 are studied. This work aims at better understanding the influence of poling on the mechanical properties of this copolymer. To explain the one decade mechanical modulus drop observed across the Curie transition, a stiffening process of the amorphous phase due to the local electric fields in the ferroelectric crystals is proposed. In poled P(VDF‐TrFE), these fields are preferentially aligned resulting in a more stable and higher modulus below the Curie transition. This hypothesis accounts for the lower dielectric signals obtained with the poled sample. Through the Curie transition, the vanishing of these local electric fields, stemming from progressive disorientation and conversion of ferroelectric crystals to paraelectric ones, releases the constraints on the amorphous phase, leading to a storage modulus drop typical of a viscoelastic transition. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 1414–1422     

Evaluation of piezoelectric PVDF polymers for use in space environments. III. Comparison of the effects of vacuum UV and gamma radiation

Films of piezoelectric PVDF and P(VDF‐TrFE) were exposed to vacuum UV (115–300 nm VUV) and γ‐radiation to investigate how these two forms of radiation affect the chemical, morphological, and piezoelectric properties of the polymers. The extent of crosslinking was almost identical in both polymers after γ‐irradiation, but surprisingly, was significantly higher for the TrFE copolymer after VUV‐irradiation. Changes in the melting behavior were also more significant in the TrFE copolymer after VUV‐irradiation due to both surface and bulk crosslinking, compared with only surface crosslinking for the PVDF films. The piezoelectric properties (measured using d₃₃ piezoelectric coefficients and D‐E hysteresis loops) were unchanged in the PVDF homopolymer, while the TrFE copolymer exhibited more narrow D‐E loops after exposure to either γ‐ or VUV‐radiation. The more severe damage to the TrFE copolymer in comparison with the PVDF homopolymer after VUV‐irradiation is explained by different energy deposition characteristics. The short wavelength, highly energetic photons are undoubtedly absorbed in the surface layers of both polymers, and we propose that while the longer wavelength components of the VUV‐radiation are absorbed by the bulk of the TrFE copolymer causing crosslinking, they are transmitted harmlessly in the PVDF homopolymer. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3253–3264, 2006     

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.     

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     

Evaluation of piezoelectric PVDF polymers for use in space environments. II. Effects of atomic oxygen and vacuum UV exposure

The effects of atomic oxygen (AO) and vacuum UV radiation simulating low Earth orbit conditions on two commercially available piezoelectric polymer films, poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride‐trifluoroethylene) P(VDF‐TrFE), have been studied. Surface erosion and pattern development are significant for both polymers. Erosion yields were determined as 2.8 × 10^?24 cm³/atom for PVDF and 2.5 × 10^?24 cm³/atom for P(VDF‐TrFE). The piezoelectric properties of the residual material of both polymers were largely unchanged after exposure, although a slight shift in the Curie transition of the P(VDF‐TrFE) was observed. A lightly cross‐linked network was formed in the copolymer presumably because of penetrating vacuum ultraviolet (VUV) radiation, while the homopolymer remained uncross‐linked. These differences were attributed to varying degrees of crystallinity and potentially greater absorption, and hence damage, of VUV radiation in P(VDF‐TrFE) compared with PVDF. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2503–2513, 2005     

Synthesis and characterization of poly(vinylidene fluoride‐co‐chlorotrifluoroethylene)‐grafted‐poly(acrylonitrile) via single electron transfer–living radical polymerization process

Preparation of functional fluoromaterials through chemical modification of traditional fluoropolymers has been recognized as an economic and convenient strategy to expand the application areas of fluoropolymers. Poly(vinylidene fluoride‐co‐chlorotrifluoroethylene)‐grafted‐polyacrylonitrile (P(VDF‐co‐CTFE)‐g‐PAN) has been successfully synthesized via single electron transfer–living radical polymerization (SET–LRP) process initiated with macroinitiator P(VDF‐co‐CTFE) in the presence of trace amount of Cu(0)/tris(2(dimethylamino)ethyl)amine (Me₆‐TREN) in dimethyl sulfoxide (DMSO) at ambient temperature. The typical side reactions happened on P(VDF‐co‐CTFE) induced by the nitrogen‐containing solvents and high reaction temperature in atom transfer radical polymerization process could be avoided in SET–LRP process by using the mild reaction conditions. Well‐controlled polymerization features were observed under varied reaction conditions including the different reaction temperature, catalyst concentration, as well as monomer amount in feed. An induction period of 0.5–1.0 h in the polymerization procedure was observed at low temperature, which may be attributed to the Cu₂O from the surface of the Cu(0) powder. When Cu(0) catalyst is activated, the introduction period is eliminated. The polymerization rates were decelerated by adding excessive Me₆‐TREN for the formation of more stable CuCl₂/(Me₆‐TREN)₂. The structure of P(VDF‐co‐CTFE)‐g‐PAN was demonstrated by FTIR, NMR, DSC, and TGA. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Hydrophobic/hydrophilic P(VDF‐TrFE)/PHEA polymer blend membranes

Polymer blend membranes have been obtained consisting of a hydrophilic and a hydrophobic polymers distributed in co‐continuous phases. In order to obtain stable membranes in aqueous environments, the hydrophilic phase is formed by a poly(hydrohyethyl acrylate), PHEA, network while the hydrophobic phase is formed by poly(vinylidene fluoride‐co‐trifluoroethylene) P(VDF‐TrFE). To obtain the composites, in a first stage, P(VDF‐TrFE) is blended with poly(ethylene oxyde) (PEO), the latter used as sacrificial porogen. P(VDF‐TrFE)/PEO blend membranes were prepared by solvent casting at 70°C followed by cooling to room temperature. Then PEO is removed from the membrane by immersion in water obtaining a P(VDF‐TrFE) porous membrane. After removing of the PEO polymer, a P(VDF‐TrFE) membrane results in which pores are collapsed. Nevertheless the pores reopen when a mixture of hydroxethyl acrylate (HEA) monomer, ethyleneglycol dimethacrylate (as crosslinker) and ethanol (as diluent) is absorbed in the membrane and subsequent polymerization yields hybrid hydrophilic/hydrophobic membranes with controlled porosity. The membranes are thus suitable for lithium‐ion battery separator membranes and/or biostable supports for cell culture in biomedical applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 672–679     

Effect of biaxial orientation on dielectric and breakdown properties of poly(ethylene terephthalate)/poly(vinylidene fluoride‐co‐tetrafluoroethylene) multilayer films

Polymer films with enhanced dielectric and breakdown properties are essential for the production of high energy density polymer film capacitors. By capitalizing on the synergistic effects of forced assembly nanolayer coextrusion and biaxial orientation, polymer multilayer films using poly(ethylene terephthalate) (PET) and a poly(vinylidene fluoride‐co‐tetrafluoroethylene) [P(VDF‐TFE)] copolymer were produced. These films exhibited breakdown fields, under a divergent field using needle/plane electrodes, as high as 1000 kV mm^?1. The energy densities of these same materials, under a uniform electric field measured using plane/plane electrodes, were as high as 16 J cm^?3. The confined morphologies of both PET and P(VDF‐TFE) were correlated to the observed breakdown properties and damage zones. On‐edge P(VDF‐TFE) crystals induced from solid‐state biaxial stretching enhanced the effective P(VDF‐TFE) layer dielectric constant and therefore increased the dielectric contrast between the PET and P(VDF‐TFE) layers. This resulted in additional charge buildup at the layer interface producing larger tree diameters and branches and ultimately increasing the breakdown and energy storage properties. In addition to energy storage and breakdown properties, the hysteresis behavior of these materials was also evaluated. By varying the morphology of the P(VDF‐TFE) layer, the low‐field dielectric loss (or ion migration behavior) could be manipulated, which in turn also changed the observed hysteresis behavior. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 882–896     

Infrared spectroscopic investigation of chain conformations and interactions in P(VDF‐TrFE)/PMMA blends

The blending between poly(methyl methacrylate) (PMMA) and ferroelectric (vinylidene fluoride‐trifluorethylene) [P(VDF‐TrFE)] copolymer chains has been investigated by Fourier transform infrared (FTIR) spectroscopy over the full range of composition, for the copolymer with 50 mol % of trifluorethylene [TrFE]. The FTIR spectra revealed an absorption band at 1643 cm⁻¹, characteristic of the blend and absent in the individual constituents. We attributed this band to the interaction of the carbonyl group of the PMMA side chains with the disordered helical chains present in the amorphous region of the P(VDF‐TrFE). We investigated the consequences of adding PMMA onto the formation of the all trans conformation of the copolymer chains and we demonstrated that the effects of thermal heating on the spectra are relevant only for the samples where the ferroelectric semicrystalline phase is present. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 34–40, 2000     

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     

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     

Effects of electron irradiation on poly(vinylidene fluoride–trifluoroethylene) copolymers studied by solid‐state nuclear magnetic resonance spectroscopy

The effects of electron irradiation on the molecular chemical structure, conformation, mobility, and phase transition of vinylidene fluoride (VDF) and trifluoroethylene (TrFE) copolymer have been investigated with variable‐temperature, solid‐state ¹⁹F nuclear magnetic resonance (NMR). It has been found that electron irradiation converts all‐trans conformations of both VDF‐rich and TrFE‐containing segments into dynamically mixed trans–gauche conformations accompanied by a simultaneous ferroelectric‐to‐paraelectric (or amorphous) transition. The variable‐temperature ¹⁹F magic‐angle‐spinning spectra results show that the paraelectric phase melts at much lower temperatures in irradiated films than in an unirradiated sample. Moreover, ¹⁹F NMR relaxation data (spin–lattice relaxation times in both the laboratory and rotating frames) reveal that electron irradiation enhances the molecular motion in paraelectric regions, whereas the molecular motion in a high‐temperature amorphous melt (>100 °C) is more constrained in irradiated films. Besides these physical changes, electron irradiation also induces the formation of several CF₃ groups. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1714–1724, 2006     

Oxygen‐sensing properties of 5,10,15,20‐tetraphenylporphinato platinum(II) and palladium(II) covalently bound on poly(isobutyl‐co‐2,2,2‐trifluoroethyl methacrylate)

A novel methacrylate monomer bearing 5,10,15,20‐tetraphenylporphyrinato palladium(II) (PdTPP) (monomer 1a ) was synthesized and copolymerized with isobutyl methacrylate (IBM) and 2,2,2‐trifluoroethyl methacrylate (TFEM) to give poly (IBM‐co‐TFEM) bearing PdTPP (copolymer 2a ) as a dye‐conjugated oxygen‐permeable polymer for pressure‐sensitive paint applications. The introduction of PdTPP into copolymer 2a was confirmed by UV–vis spectroscopy and extended X‐ray absorption fine structure analysis. The Stern–Volmer plots of the copolymer 2a and a mixture of PdTPP and poly(IBM‐co‐TFEM) both showed downward curvature, unlike that of the platinum complex analogue (copolymer 2b ) previously reported. The plots were successfully fitted with a two‐site model to give two distinct Stern–Volmer constants (K_SV1 and K_SV2) and the partition ratio f₁. Interestingly, the f₁ values for the copolymer 2a were almost constant at about 0.98, whereas those of the mixture of PdTPP and poly(IBM‐co‐TFEM) increased from 0.889 to 0.967 as the temperature was increased. This finding suggests that there are two distinct microheterogeneities, one temperature‐dependent and the other temperature‐independent, in the mixture of PdTPP and poly(IBM‐co‐TFEM). The dye‐conjugation approach effectively eliminates the temperature‐dependent, but not the temperature‐independent microheterogeneity. The luminescence decays of copolymers 2a and 2b and the corresponding mixtures in the absence of oxygen indicated that the temperature‐dependent microheterogeneity involves an oxygen diffusion process, whereas the temperature‐independent one appears to be inherent nature in PdTPP. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 663–670, 2010     

Combination of nitroxide‐mediated polymerization and SET‐LRP for the synthesis of high molar mass branched and star‐branched poly(n‐butyl acrylate) characterized by size exclusion chromatography and rheology

Branched and star‐branched polymers were successfully synthesized by the combination of two successive controlled radical polymerization methods. A series of linear and star poly(n‐butyl acrylate)‐co‐poly(2‐(2‐bromoisobutyryloxy) ethyl acrylate) statistical copolymers, P(nBA‐co‐BIEA)_x, were first synthesized by nitroxide‐mediated polymerization (NMP at T > 100 °C). The subsequent polymerization of n‐butyl acrylate by single electron transfer‐living radical polymerization (SET‐LRP at T = 25 °C), initiated from the brominated sites of the P(nBA‐co‐BIEA)_x copolymer, produced branched or star‐branched poly(n‐butyl acrylate) (PnBA). Both types of polymerizations (NMP and SET‐LRP) exhibited features of a controlled polymerization with linear evolutions of logarithmic conversion versus time and number‐average molar masses versus conversion for final M_n superior to 80,000 g mol^?1. The branched and star‐branched architectures with high molar mass and low number of branches were fully characterized by size exclusion chromatography. The Mark–Houwink Sakurada relationship and the analysis of the contraction factor (g′ = ([η]_branched/[η]_linear)_M) confirmed the elaboration of complex PnBA. The zero‐shear viscosities of the linear, star‐shaped, branched, and star‐branched polymers were compared. The modeling of the rheological properties confirmed the synthesis of the branched architectures. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis,characterization, and properties of tunable thermosensitive amphiphilic dendrimer‐star copolymers with Y‐shaped arms

Novel and well‐defined amphiphilic dendrimer‐star copolymer poly(ε‐caprolactone)‐block‐(poly(2‐(2‐methoxyethoxy)ethylmethacrylate‐co‐oligo(ethylene glycol) methacrylate))₂ with Y‐shaped arms were synthesized by the combination of ring‐opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The investigation of thermal properties and the analysis of crystalline morphology indicate that the high‐branched structure of dendrimer‐star copolymers with Y‐shaped arms and the presence of amorphous P(MEO₂MA‐co‐OEGMA) segments together led to the complete destruction of crystallinity of the PCL segments in the dendrimer‐star copolymer. In addition, the hydrophilicity–hydrophobicity transition of the dendrimer‐star copolymer film can be achieved by altering the external temperatures. The amphiphilic copolymers can self‐assemble into spherical nanomicelles in water. Because the lower critical solution temperature of the copolymers can be adjusted by varying the ratio of MEO₂MA and OEGMA, the tunable thermosensitive properties can be observed by transmittance, dynamic laser light scattering, and transmission electron microscopy (TEM). The release rate of model drug chlorambucil from the micelles can be effectively controlled by changing the external temperatures, which indicates that these unique high‐branched amphiphilic copolymers have the potential applications in biomedical field. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Electrosynthesis and electrochromic properties of free‐standing copolymer based on oligo(oxyethylene) cross‐linked 2,2’‐bithiophene and 3,4‐ethylenedioxythiophene

Oligo(oxyethylene) chains cross‐linked 2,2’‐bithiophene (BT‐E5‐BT) has been synthesized successfully. A free‐standing copolymer film based on BT‐E5‐BT and 3,4‐ethylenedioxythiophene (P(BT‐E5‐BT‐co‐EDOT)) has been synthesized by electrochemical polymerization. The electrical conductivity of P(BT‐E5‐BT‐co‐EDOT) copolymer (16 S m^?1) has improved by four orders of magnitude compared to the homopolymer of BT‐E5‐BT (P(BT‐E5‐BT), 5 × 10^?3 S m^?1) at room temperature. Both homopolymer and copolymer films exhibit well‐defined redox and satisfied coloration efficiency. Spectroelectrochemistry studies indicate that the P(BT‐E5‐BT‐co‐EDOT) has a lower band gap in the range of 1.83–1.90 eV and shows more plentiful electrochromic colours (green, blue, purple and salmon pink) compared with the homopolymer P(BT‐E5‐BT). The Copolymer P(BT‐E5‐BT‐co‐EDOT) shows the moderate optical contrast (26% of 480 nm) and coloration efficiency (205.41 cm^?1 C^?2). The copolymer method provides a novel way to fabricate a free‐standing organic electrochromic device. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1583–1592