Polymerization of propiolaldehyde. IV. Synthesis of a functional polymer having an ethynyl group

The cationic homopolymerization and copolymerization of propiolaldehyde were carried out with use of boron trifluoride etherate as an initiator at the temperatures of 0 to ?78°C. Poly(ethynyl)oxymethylene was prepared by the homopolymerization at ?78°C, but it was readily depolymerized to the monomer. The cationic copolymerization with styrene at ?78°C proceeded almost exclusively through the aldehyde addition and a new functional copolymer was obtained. With a rise in polymerization temperature, the ethynyl addition was mixed slightly.