Synthesis of Norbornene Block Copolymers Containing Polyhedral Oligomeric Silsesquioxane by Sequential Ring-Opening Metathesis Polymerization

摘要

The synthesis of a series of poly(POSS-NBE-b-MTD)copolymers was successfully accomplished,taking advantage of sequential,ring-opening,metathesis block copolymerization using RuCl_2(=CHPh)(PCy_3)_2 catalyst.By using cyclopentyl-POSS-norbornene(POSS-NBE)monomer as the first block in the block copolymer,living poly(POSS-NBE)with controlled molecular weight and narrow molecular weight distribution was produced.Then,poly(POSS-NBE-b-MTD)copolymers were successfully prepared,in which sequential monomer addition of meth-yltetracyclododecene(MTD)to the living poly(POSS-NBE)chain ends was utilized to achieve quantitative crossover efficiency.Characterization by ~1H NMR spectroscopy and GPC confirmed the high definition and structural integrity of the poly(POSS-NBE-b-MTD)copolymers.Thermal properties and morphologies of the POSS-containing block copolymer nanocomposites were also investigated by using thermogravimetric analysis(TGA),transmission electron microscopy(TEM),and wide-angle X-ray scattering(WAXS).