Cationic copolymerization of 1,3‐dioxolanes and 1,3‐dioxanes with 3,4‐dihydro‐2H‐pyran‐2‐methyl(3,4‐dihydro‐2H‐pyran‐2‐carboxylate). Nonfriable pyranyl foams

摘要

AbstractVarious substituted difunctional 1,3‐dioxolanes and 1,3‐dioxanes were copolymerized with a cyclic vinyl ether, 3,4‐dihydro‐2H‐pyran‐2‐methyl(3,4‐dihydro‐2H‐pyran‐2‐carboxylate), in the presence of boron trifluoride etherate catalyst. The copolymerizations proceeded rapidly and exothermally when initiated at room temperature and produced thermosetting resins. The copolymer products possess improved abrasion resistance and toughness as compared with homopolymer of the di(dihydropyranyl) monomer. As a practical consequence of these copolymerizations it is possible to prepare low‐density pyranyl rigid foams with impro