Lipases from different sources were screened to determine their relative performance to catalyze omega-pentadecalactone (PDL) ring-opening polymerization from the hydroxyl group of 2-hydroxyethyl methacrylate (2-HEMA) and omega-hydroxyl-omega'-methaerylate-poly(ethylene glycol) [PEGMA (M-n 360)]. Novozym 435 was found to be the most active biocatalyst for 2-HEMA/PEGMA-initiated PDL ring-opening polymerizations at 70 degreesC for 48 h in toluene (1:2 w/v of monomers). Thus, 2-HEMA-terminated PPDL was synthesized in yields of similar to80% and with < 2 mol % carboxyl-terminated PPDL from initiation by water. Similarly, PEGMA-terminated PPDL was prepared. The free radical polymerizations of the corresponding macromers were carried out with AIBN at 70 degreesC in toluene. Thermal analysis of 2-HEMA-co-b-PPDL and PEGMA-co-b-PPDL macromers showed them to be stable and highly crystalline (T. from 80 to 90 degreesC). In PEGMA-co-b-PPDL macromers, X-ray diffraction measurements show that the ethylene oxide units of the PEG block crystallize in the PPDL lattice. The main change observed upon polymerization of the macromers is a decrease of crystallinity (by both DSC and X-ray measurements).