Absorbable heterochain polymers carrying acid or basic groups, capable of ionic conjugation with basic or acidic bioactive agents, respectively, are produced by free-radical addition of unsaturated functional monomers onto absorbable liquid polymers and subsequent generation of reactive functionality or by direct copolymerization of a carboxylic initiator with cyclic monomers to produce liquid carboxyl-bearing copolyesters or polyester carbonates.