Development and application of latent hydrosilylation catalysts.: 3. Control of activity of platinum catalysts by poly(vinyl ether) having propargyl moieties

A flexible polymer having propargyl moieties ( 2) was prepared by the cationic polymerization of vinyl monomer ( 1) derived from 4-hydroxybutyl vinyl ether and propargyl bromide. In the presence of the polymer, the catalytic activity of H 2PtCl 6 towards the hydrosilylation of triethylsilane and trimethylvinylsilane was found to be retarded effectively at ambient temperature, but not on heating. Compared to the monomeric propargyl derivatives, the polymeric system was quite effective in controlling the catalytic activity. Under the same concentration of acetylene moieties and H 2PtCl 6, the initiating temperature of the present system was ca. 50°C higher than for the catalyst composed of the monomeric propargyl derivatives, but was ca. 20°C lower than for that consisting of the propargylated polystyrene derivative that the authors have reported recently. Effective control of the crosslinking reaction of silicone resin was also achieved using the present latent system.