New functional aliphatic polyesters by chemical modification of copolymersof epsilon-caprolactone with gamma-(2-bromo-2-methylpropionate)-epsilon-caprolactone, gamma-bromo-epsilon-caprolactone, and a mixture of beta- and gamma-ene-epsilon-caprolactone

New functional aliphatic polyesters were prepared by chemical modification of brominated copolyesters. Poly(epsilon -caprolactone)-co-poly(gamma-(2-br omo-2-methylpropionate)-epsilon -caprolactone) copolymer was prepared and s uccessfully converted into copolyester bearing methacrylate double bonds by dehydrohalogenation of the pendant tertiary alkyl bromides, thus leading t o cross-linkable polyester. The tertiary alkyl bromide groups of the origin al copolyester were also quaternized by reaction with pyridine, although so me side reactions occurred which Limited the reaction yield. Nevertheless, quaternization of the bromide groups of the poly(epsilon -caprolactone)-co- poly(gamma -bromo-epsilon -caprolactone) copolymer proved to be quantitativ e and to occur without degradation of the polyester chains. This general st rategy paves the way to either amphiphilic copolyesters or water-soluble po lyesters. The poly(epsilon -caprolactone)-co-poly(gamma -bromo-epsilon -cap rolactone) lactone) copolymer was also quantitatively converted into unsatu rated copolyester by dehydrohalogenation with formation of double bonds inc luding acrylic-type double bonds. As an alternative, gamma -bromo-epsilon - caprolactone was first dehydrohalogenated, and the unsaturated cyclic monom er was copolymerized with epsilon -caprolactone. Finally, the nonconjugated double bonds of the copolyesters were oxidized into epoxides, except for t he acrylic-type unsaturations which remained unchanged.