Abstract
In this work, a series of hydrosilanes including phenylsilane, diphenylsilane, triethylsilane (TES), and tris(trimethylsilyl)silane combined with catalytical amount of platinum complex such as dichloro(1,5-cyclooctadiene) platinum (COD) and dichloro(dicyclopentadienyl)platinum have been used to initiate the polymerization of vinyl acetate (VAc) at 70-95 ℃. An ultrahigh molecular weight PVAc with number-average molecular weight (M<SUB>n</SUB>) up to 1.17×10<SUP>6</SUP> Da and polydispersity index (PDI) of 2.59 has been synthesized using TES as an initiator in the presence of 9.7 ppm of COD. A kinetic study indicates that the polymerization at VAc/TES/COD molar ratio = 3.0×10<SUP>5</SUP> : 60 : 1 smoothly reached 81.0% conversion in 28.0 h at 85 ℃, producing PVAc with M<SUB>n</SUB> increasing linearly from 1.41×105 to 6.01×10<SUP>5</SUP> Da with the increase of monomer conversion. A mechanistic investigation revealed that COD was firstly reduced by reductive TES, producing Pt nanoparticles and corresponding silane radicals to initiate the polymerization of VAc.
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