Cationic Ring-Opening Isomerization Polymerization of Bicyclo Ortho Esters Initiated by Carbon Black

Abstract

The cationic ring-opening isomerization polymerization of bicyclo ortho esters (BOE) such as 1-phenyl-4-ethyl-2,6,7-trioxabicyclo[2.2.2]octane and 1,4-diethyl-2,6,7-trioxabicyclo[2.2.2]octane initiated by carbon black was investigated. The polymerization scarcely proceeded in the absence of carbon black. But in the presence of channel black having carboxyl groups, the polymerization of BOE was initiated at 130°C to give a polyether containing an ester group in the side chain. The initiating ability of carbon black increased with increase in its carboxyl group content. Furnace black having no carboxyl group was unable to initiate the polymerization. Based on these results, it was concluded that the carboxyl group on carbon black is capable of initiating the polymerization of BOE. During the polymerization, a part of the polymers formed was grafted onto carbon black via the termination of growing polymer chain. Furthermore, the ring-opening isomerization polymerization of BOE was found to be initiated by an acylium perchlorate group introduced onto the carbon black surface. The polyether containing ester group in side chain was effectively grafted from carbon black, because the propagation of the polymer proceeded from the acylium perchlorate group on carbon black.