| 초록 |
Preparation and selective ring-opening polymerization of 5-membered exo methylene cyclic acetals were performed. Unsaturated cyclic acetals were prepared by dehydrochlorination of 2-alkenyl-4-chloromethyl-1,3-dioxolanes obtained from acrolein derivatives and epichlorohydrin, with sodium methoxide at ambient temperature. The cationic polymerizations of cyclic acetals with BF3OEt2 or CF3SO3H at -78°C produced only crosslinked polymers. The polymerization by CH3SO3H gave soluble poly(keto-ether) which consisted of units containing an alkenyl group in the side chain and units containing a carbon-carbon double bond in the main chain. In the polymerization of one exo acetal, unexpected signals around δ1.0 ppm in 1H-NMR spectrum appeared with elapse of time, while the content of carbon-carbon double bonds in the polymer decreased. In the polymerization of the other acetal, however, the signal around δ1.0 ppm could not be observed, and the signal intensities did not decrease with time.
|
