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31 results on '"Lei, Yanda"'

11. Immobilization of Xanthate Agent on Titanium Dioxide and Surface Initiated RAFT Polymerization

Author

Lei, Yanda, Wang, Tongxin, Mitchell, James W, and Chow, Laurence C

Subjects
technology, industry, and agriculture, macromolecular substances, Article
Abstract

Surface modification of titanium dioxide (TiO2) nanoparticle is essential to control its surface properties, thereby to enhance its cell penetration capability, reduce its cytotoxicity, or improve its biocompatibility. In order to graft polyvinyl acetate onto TiO2 nanoparticles, xanthate was chemically immobilized on the surface of TiO2 by acylation followed by nucleophilic substitution with a carbodithioate salt. Reversible addition fragmentation chain transfer polymerization was conducted to graft vinyl acetate onto the surface of TiO2. Both the TiO2-xanthate and TiO2-polyvinyl acetate hybrids were characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The chemical immobilization of xanthate on the surface of TiO2 and the subsequent controlled polymerization provide useful insight for decoration and modification of TiO2 and other nanoparticles.

Published
2014

30. Thiol-containing ionic liquid for the modification of styrene-butadiene rubber/silica composites.

Author

Lei, Yanda, Tang, Zhenghai, Zhu, Lixin, Guo, Baochun, and Jia, Demin

Subjects
THIOLS, IONIC liquids, STYRENE-butadiene rubber, SILICA, HYDROGEN bonding
Abstract

To introduce thiol-ene chemistry in the modification of composites by ionic liquid (IL), a novel functional IL, 1-methylimidazolium mercaptopropionate (MimMP), was synthesized and investigated as a modifier for styrene-butadiene rubber/silica composites. MimMP could be hydrogen-bonded with silica and react with the double bonds of rubber chains via thiol-ene chemistry. The filler networking, curing behavior, filler dispersion, crosslink density, and mechanical performance were fully studied. The filler networking in the uncured rubber compounds was effectively restrained. The vulcanization was largely accelerated by MimMP. The interfacial interaction was quantitatively evaluated and found to consistently increase with increasing MimMP. The mechanical performance and abrasion resistance of the modified vulcanizates improved considerably. The remarkable improvements were mainly ascribed to the improved interfacial structure comprised of MimMP-silica hydrogen bonding and MimMP-rubber covalent bonds via thiol-ene chemistry. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Published
2012
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31. Immobilization of Xanthate Agent on Titanium Dioxide and Surface Initiated RAFT Polymerization.

Author

Lei Y, Wang T, Mitchell JW, and Chow LC

Abstract

Surface modification of titanium dioxide (TiO 2 ) nanoparticle is essential to control its surface properties, thereby to enhance its cell penetration capability, reduce its cytotoxicity, or improve its biocompatibility. In order to graft polyvinyl acetate onto TiO 2 nanoparticles, xanthate was chemically immobilized on the surface of TiO 2 by acylation followed by nucleophilic substitution with a carbodithioate salt. Reversible addition fragmentation chain transfer polymerization was conducted to graft vinyl acetate onto the surface of TiO 2 . Both the TiO 2 -xanthate and TiO 2 -polyvinyl acetate hybrids were characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The chemical immobilization of xanthate on the surface of TiO 2 and the subsequent controlled polymerization provide useful insight for decoration and modification of TiO 2 and other nanoparticles.

Published
2014

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