Solution and aqueous miniemulsion polymerizations of vinyl chloride (VC) mediated by (3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl-2-((ethoxycarbonothioyl)thio) propanoate) (X1) were studied. The living characters of X1-mediated solution and miniemulsion polymerizations of VC were confirmed by polymerization kinetics. The miniemulsion polymerization exhibits higher rate than solution polymerization. Final conversions of VC in the reversible addition-fragmentation chain transfer (RAFT) miniemulsion polymerization reach as high as 87% and are independent of X1 concentration. Initiation process of X1-mediated RAFT miniemulsion polymerization is controlled by the diffusion–adsorption process of prime radicals. Due to the heterogeneity of polymerization environments and concentration fluctuation of RAFT agent in droplets or latex particles, PVCs prepared in RAFT miniemulsion exhibit relatively broad molecular weight distribution. Furthermore, chain extensions of living PVC (PVC-X) with VC, vinyl acetate (VAc), and N-vinylpyrrolidone (NVP) reveal that PVC-X can be reinitiated and extended, further confirming the living nature of VC RAFT polymerization. PVC-b-PVAc diblock copolymer is successfully synthesized by the chain extension of PVC-X in RAFT miniemulsion polymerization. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2092–2101

A straightforward strategy is described to synthesize poly(ϵ-caprolactone)-graft-poly(N-isopropylacrylamide) (PCL-g-PNIPAAm) amphiphilic graft copolymers consisting of potentially biodegradable polyester backbones and thermoresponsive grafting chains. PCL with pendent chlorides was prepared by ring-opening polymerization, followed by conversion of the pendent chlorides to azides. Alkyne-terminated PNIPAAm was synthesized by atom transfer radial polymerization. Then, the alkyne end-functionalized PNIPAAm was grafted onto the PCL backbone by a copper-catalyzed azide–alkyne cycloaddition. PCL-g-PNIPAAm graft copolymers self-assembled into spherical micelles comprised of PCL cores and PNIPAAm coronas. The critical micelle concentrations of the graft copolymers were in the range 7.8–18.2 mg L⁻¹, depending on copolymer composition. Mean hydrodynamic diameters of micelles were in the range 65–135 nm, which increased as the length of grafting chains grew. PCL-g-PNIPAAm micelles were thermosensitive and aggregated upon heating. © 2014 Society of Chemical Industry

The crystallization kinetics and crystalline structure of the biodegradable polymorphic polymers, poly(butylene adipate) (PBA) and poly(butylene adipate-co-hexamethylene adipate), in the microparticles and nanoparticles covered by poly(vinyl alcohol) (PVA), and those on the PVA substrate were investigated by differential scanning calorimetry, wide-angle X-ray diffraction, and Fourier transform infrared spectroscopy. Both the polymers crystallized in the particle state and on the PVA substrate showed higher crystallization temperatures in the nonisothermal melt crystallization and shorter crystallization times in the isothermal crystallization; this indicated a faster crystallization of the polymer in the particle state and on the PVA substrate than that of the bulk sample. Furthermore, the polymers in the particle state and on the PVA substrate showed the preferential formation of the β-type crystalline form of PBA compared to the bulk one. The mechanism for the effects of the PVA layer or substrate on the crystallization kinetics and crystalline structure of PBA and its copolyesters are discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39600.

Thermoresponsive graft copolymers of ε-caprolactone and N-isopropylacrylamide were synthesized by a combination of ring-opening polymerization and the sequential atom transfer radical polymerization (ATRP). The copolymer composition, chemical structure, and the self-assembled structure were characterized. The graft length and density of the copolymers were well controlled by varying the feed ratio of monomer to initiator and the fraction of chlorides along PCL backbone, which is acting as the macroinitiator for ATRP. In aqueous solution, PCL-g-PNIPAAm can assemble into the spherical micelles which comprise of the biodegradable hydrophobic PCL core and thermoresponsive hydrophilic PNIPAAm corona. The critical micelle concentrations of PCL-g-PNIPAAm were determined under the range of 6.4–23.4 mg/L, which increases with the PNIPAAm content increasing. The mean hydrodynamic diameters of PCL-g-PNIPAAm micelles depend strongly on the graft length and density of the PNIPAAm segment, allowing to tune the particle size within a wide range. Additionally, the PCL-g-PNIPAAm micelles exhibit thermosensitive properties and aggregate when the temperature is above the lower critical solution temperature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41115.

The epoxide-terminated low-molecular-weight poly(phenylene oxide) (PPO), EPPO, was synthesized by modifying the terminal hydroxyl group of PPO and it was reactively blended with epoxy-novolac resin (EPN). The curing kinetics, phase morphology, thermal stability, dielectric property, and water absorption behavior of the cured EPN/EPPO blends were investigated and compared with the unmodified EPN/PPO blends. As revealed by the FTIR and DSC analysis, EPPO takes part in the curing reaction and forms a reactive blend with EPN. The curing rate of both EPN/PPO and EPN/EPPO blends first increases and then decreases with increasing the PPO or EPPO fraction. The blends have lower degree of curing than neat EPN, due to the steric hindrance effects of PPO or EPPO. Because of the reaction between blend components, EPN/EPPO blends show faster curing rate and higher degree of curing than the corresponding EPN/PPO blends. The reactive blending improves the dispersion of EPPO in EPN matrix and the EPN/EPPO blend forms a co-continuous morphology even at a low EPPO content, compared to the typical sea-island morphology of the EPN/PPO blend. The EPN/EPPO blend has remarkable smaller dielectric constant, dissipation factor, and water absorption than neat EPN. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Effects of cyanuric acid (CA) on nonisothermal and isothermal crystallization, melting behavior, and spherulitic morphology of bacterial copolyesters of poly(3-hydroxybutyrate), i.e., poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), have been investigated. CA has excellent acceleration effectiveness on the melt crystallization of bacterial PHB, PHBV, and PHBH, better than the nucleating agents reported in the literatures, such as boron nitride, uracil, and orotic acid. PHBV and PHBH do not crystallize upon cooling from the melt at 10°C/min, while they are able to complete crystallization under the same conditions with an addition of 1% CA, with a presence of sharp crystallization exotherm at 75–95°C. Isothermal crystallization kinetics of neat and CA-containing PHBV and PHBH were analyzed by Avrami model. Crystallization half-times (t_1/2) of PHBV and PHBH decrease dramatically with an addition of CA. The melting behavior of isothermally melt-crystallized PHBV and PHBH is almost not influenced by CA. Spherulitic numbers of PHBV and PHBH increase and the spherulite sizes reduce with an incorporation of CA. Nucleation densities of PHBV and PHBH increase by 3–4 orders of magnitude with a presence of 1% CA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013