MESOPOROUS MOLECULAR SIEVES IMMOBILIZED CATALYSTS FOR POLYMERIZATION OF PHENYLACETYLENE AND ITS DERIVATIVES

摘要

New hybrid catalysts for polymerization of phenylacetylene and its derivatives into high-molecular-weight polyphenylacetylenes were prepared by anchoring [Rh(cod)X]_2 (X = Cl, OCH_3) on siliceous mesoporous molecular sieves MCM-41 and SBA-15. The polymerization proceeds on the catalyst surface and the polymer formed is continuously released into the liquid phase from which it can be easily isolated. In comparison with homogeneous analogues, the hybrid catalysts exhibit comparable or even higher polymerization activity. Especially, the immobilization of Rh-complexes brings about increase in molecular weight of polymers formed and parallel reduction in formation of oligomeric by-products. The stereoselectivity of Rh homogeneous catalysts leading to the formation of high-cis-polyacetylenes is preserved. Although hybrid catalysts are resistant to Rh leaching, a significant catalysts deactivation was observed during polymerization that strongly reduces the possibility of an efficient reusing of tested hybrid catalysts. This deactivation most probably consists in liberation of cod ligand from anchored Rh species during polymerization.