Nanocomposites through copolymerization of a polyhedral oligomeric silsesquioxane and methyl methacrylate

The mechanical properties and thermal stability of polymers can be enhanced through the formation of nanocomposites. Nanocomposites consisting of hybrid copolymers of methacrylcyclohexyl polyhedral oligomeric silsesquioxane (POSS-1) and methyl methacrylate (MMA) with up to 92 wt % (51 mol %) POSS-1 and with superior thermal properties were synthesized using solution polymerization. The POSS-1 contents of the copolymers were similar to or slightly higher than those in the feeds, the polydispersity indices were relatively low, and the degree of polymerization decreased with increasing POSS-1 content. POSS-1 enhanced the thermal stability, increasing the degradation temperature, reducing the mass loss, and preventing PMMA-like degradation from propagating along the chain. The mass loss was reduced in a high POSS-1 content copolymer since the polymerization of POSS-1 with itself reduced sublimation. Exposure to 450 degrees C produced cyclohexyl-POSS-like remnants in the POSS-1 monomer and in all the copolymers. The degradation of these remnants, for the copolymers and for the POSS-1 monomer, yielded 75% SiO2 and an oxidized carbonaceous residue. (c) 2007 Wiley Periodicals, Inc.