Changjie Yin

Fast and facile fabrication of porous polymer particles via thiol–ene suspension photopolymerization

A fast and facile method of preparing porous polymer particles via thiol–ene suspension photopolymerization was studied. The porous particles were fabricated by adding the porogen to the click chemistry system. In this paper, the photopolymerization of dipentaerythritol hexakis (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptopropionate), 1,3,5-tri-2-propenyl-1,3,5-triazine- 2,4,6(1H,3H,5H)-trione, sodium dodecyl sulfate, chloroform and different amounts of linear polymer porogen (polymethyl methacrylate, PMMA) was discussed in detail. The two crucial factors, polymerization time and amount of porogen, were investigated. It was demonstrated that the conversion of monomers could reach 80% within 15 s of irradiation, which further verified the high efficiency of click chemistry. By varying the amount of PMMA, we were able to tailor the particle size, pore diameters and morphology of the porous particles. Results of the mercury porosimetry indicated that the median pore diameter of particles was about 12.39 μm and the surface area was 4.393 m2 g−1. Moreover, the Tg of the particles given by DSC was about 45 °C.

Synthesis and characterization of brush-like multigraft copolymers PnBA-g-PMMA by a combination of emulsion AGET ATRP and emulsion polymerization

In this paper, poly(n-butyl acrylate)-g-poly(methyl methacrylate) multigraft copolymers were synthesized by macromonomer technique and miniemulsion copolymerization. The PMMA macromonomers were obtained by an activator generated by electron transfer atom transfer radical polymerization (AGET ATRP) in emulsion system and subsequent allylation. Then the copolymerization of different macromonomers with nBA was carried out in miniemulsion system, obtaining multigraft copolymers with high molecular weight. The latex particles and distribution of emulsion AGET ATRP and miniemulsion copolymerization were characterized using laser light scattering. The molecular weight and polydispersity indices of macromonomers and multigraft copolymers were analyzed by gel permeation chromatography, and the number-average molecular weight range is 187,600-554,800 g/mol for PnBA-g-PMMA copolymers. In addition, the structural characteristics of macromonomer and brush-like copolymers were determined by infrared spectra and (1)H nuclear magnetic resonance spectroscopy. The thermal performance of brush-like copolymers were characterized by differential scanning calorimetry and thermogravimetric analysis. Atomic force microscopy results showed that the degree of microphase separation was varying with increasing PMMA content in PnBA-g-PMMA. The dynamic rheometer analysis revealed that multigraft copolymer with PMMA content of 31.4% exhibited good elastomeric properties to function as a TPE. These multigraft copolymers show a promising low cost and environmental friendly thermoplastic elastomer.

Effects of Carbon Black on the Properties of HNBR Reinforced by in-situ Prepared ZDMA

Hydrogenated nitrile rubber (HNBR) filled with carbon black (CB) and in-situ prepared zinc dimethacrylate (ZDMA) was prepared by mechanical mixing method. The effects of carbon black on the vulcanization characteristics, physical and dynamic mechanical properties, thermal stability and the fracture surface morphologies of HNBR reinforced by in-situ prepared ZDMA (HNBR/ZDMA) were investigated. The results showed that, for given ZDMA loading (50 phr), with the increasing CB content, the scorch time extended, tensile strength, tear strength and elongation at break increased at first and then decreased, while the modulus at 100% and hardness increased. The comprehensive properties of the HNBR/ZDMA/CB was optimal, when the content of CB was 10 phr. DMA analysis showed that the addition of CB could enhance the storage modulus (E’) & loss modulus (E”), and decreased the glass transition temperature (Tg) of HNBR/ZDMA. TGA analysis revealed that the addition of CB could improve the thermal stability of HNBR/ZDMA. SEM analysis showed that the CB dispersed well in the HNBR/ZDMA, and the CB could improve the dispersion of ZDMA effectively.

Cure Characteristics and Mechanical Properties of Vinyltriethoxysilane Grafted Styrene-Butadiene Rubber/Silica Blends

Graft polymerization of vinyltriethoxysilane (VTES) onto styrene-butadiene rubber (SBR) was carried out in latex using potassium peroxydisulfate as an initiator. Then SBR-g-VTES/silica, SBR/TESPT/silica and SBR-g-VTES/TESPT/silica were prepared by mechanical mixing with different silica loading. The silica particles dispersed uniformly in the SBR-g-VTES networks. Among the three composites, the SBR-g-VTES/Silica blends show the highest of all. The t90 of SBR-g-VTES/TESPT/Silica composites is the shortest of all. On the other hand, the SBR-g-VTES/TESPT/silica composites exhibit highest tensile strength and hardness of all. The SBR-g-VTES/silica composites show higher tensile strength and hardness than SBR/TESPT/silica. The tanδ value (loss tangent) at −20-0°C of SBR-g-VTES/silica is slightly higher than that of SBR/TESPT/silica.