Biodegradable polymeric compositions that are liquids or pastes at temperatures below 37° C. are described. Immersion of the compositions in aqueous medium, such as body fluids, increases the viscosity of the composition resulting in the formation of a semisolid material. The polymeric material is a hydroxyalkanoic acid polyester derived from the copolymerization of at least one unsaturated hydroxy fatty acid copolymerized with hydroxyalkanoic acids of 2-6 carbons.