Abstract
An incompletely condensed cage silsesquioxane (IC-POSS)-based AB3-type monomer, tris(dimethylsilyl)-p-vinylhexaisobutyl-IC-POSS (3), was prepared by the corner-cleaved reaction of vinylheptaisobutyl-POSS (1) and subsequent capping reaction with chlorodimethylsilane. The structure of 3 was confirmed by FT-IR; 1H-, 13C-, and 29Si-NMR; and HR-FAB-MS analyses. These analyses also suggested 12.5 mol% contamination of tris(dimethylsilyl)-heptaisobutyl-IC-POSS (4). The hydrosilylation polymerization of 3 as an AB3-type IC-POSS monomer in the presence of Karstedt’s catalyst in toluene at 80 °C overnight provided a soluble polymer with a number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) of the polymer that are 3.9 × 103 and 1.39, respectively. The resulting hyperbranched polymer (HB) reacted with two molar equivalents of isoprenol or allylheptaisobutyl-POSS against the Si–H groups in the presence of Karstedt’s catalyst in toluene at 80 °C for 7 h. The HB polymers before and after post functionalization with isoprenol or allylheptaisobutyl-POSS showed 1% weight loss at 298, 285, and 358 °C, respectively, under N2. Introducing POSS units at the terminus significantly increased the thermal stability. The XRD pattern of the HB polymers showed a denser structure formed in the allylheptaisobutyl-POSS-terminated HB polymer. The refractive index of the HB polymer before post functionalization was 1.4376. Post functionalization with isoprenol and allylheptaisobutyl-POSS increased the refractive index to 1.4464 and 1.4573, respectively. An incompletely condensed cage silsesquioxane (IC-POSS)-based AB3-type monomer, tris(dimethylsilyl)-p-vinylhexaisobutyl-IC-POSS (3), was prepared by the corner-cleaved reaction of vinylheptaisobutyl-POSS (1) and subsequent capping reaction with chlorodimethylsilane. The hydrosilylation polymerization of 3 in the presence of Karstedt’s catalyst in toluene provided a soluble polymer. The refractive index of the unmodified polymer film was 1.4376. Post functionalization with isoprenol increased the dispersibility in polar organic solvents and significantly increased the glass-transition temperature. Post functionalization with allylheptaisobutyl-POSS significantly increased the thermal stability. Their refractive index varied from 1.4464 to 1.4573 upon post functionalization.
Published Version
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