SYNTHESIS AND RING-OPENING POLYMERIZATION OF 2-ACETOXYMETHYL-2-ALKYLTRIMETHYLENE CARBONATES AND OF 2-METHOXYCARBONYL-2-METHYLTRIMETHYLENE CARBONATE - A COMPARISON WITH THE POLYMERIZATION OF 2,2-DIMETHYLTRIMETHYLENE CARBONATE

The polymerization of 2-acetoxymethyl-2-alkyltrimethylene carbonates ( alkyl methyl: AMTC, alkyl = ethyl: AETC) and of 2-methoxycarbonyl-2-me thyltrimethylene carbonate (MMTC) in toluene with sec-butyllithium as initiator results in the respective polymer with yields between 78% an d 88%. The analysis of the polymer microstructure by means of NMR spec troscopy reveals linear chains without branching due to an attack of t he active chain end at the ester moiety of the repeating units. Poly(M MTC) and poly(AETC) afford crystalline materials upon precipitation fr om solution while poly- (AMTC) is amorphous; after quenching from the melt all materials are amorphous. Copolymerization of AMTC, AETC and M MTC with 2,2-dimethyltrimethylene carbonate (DTC) results in random co polymers. The kinetics of the polymerization of AETC and MMTC revealed that the ester side chain enhances the rate of propagation compared t o the polymerization of DTC. The apparent rate constants of propagatio n in toluene with lithium alcoholate as active sites at 23 degrees C w ere determined to be k(app)(DTC) = 4 . 10(-3) S-1, k(app)(AETC) = 4,28 . 10(-2) s(-1), and k(app)(MMTC) = 2,57 . 10(-2) s(-1). Studies of ri ng-chain equilibria in solution of tetrahydrofuran revealed that on th e basis of the theory of Jacobson-Stockmayer the characteristic ratios of the polymers are C-infinity(PDTC) = 7,1, C-infinity(PMMTC) = 8,6, C-infinity(PAETC) = 9,9, and C-infinity(PAMTC) = 13,4.