High-molecular-weight (co) polymers of trimethylene carbonate and D, L-lactide are efficiently crosslinked using PETA during gamma irradiation. Form-stable networks with gel contents of 86 +/- 5 to 96 +/- 1 are obtained from non-crystalline (co) polymers. Glass transition temperatures and elastic moduli of the networks can be varied by adjusting the copolymer composition. The PETA-containing (co) polymer networks are not cytotoxic. Upon incubation in macrophage cultures for 14 d, all (co) polymer films and PETA-containing network films erode to varying extents, showing that these materials can be degraded by cell-mediated erosion processes. This method is very useful for the facile preparation of TMC- and DLLA-containing form-stable networks from high-molecular-weight polymers.