Ring‐opening copolymerization of L‐lactide (LLA) and 1,3‐trimethylene carbonate (TMC) blends with LLA/TMC feed ratios from 90/10 to 50/50 was realized at 110 or at 180 °C for various time periods, using low toxic zirconium (IV) acetylacetonate (Zr(Acac)4) as initiator. The resulting copolymers exhibit different chain microstructures. Copolymers obtained at 110 °C exhibit a gradient chain structure with the presence of lactidyl sequences next to very short ones, and are semicrystalline. In contrast, copolymers obtained at 180 °C are amorphous because of a more random chain microstructure with the presence of larger amounts of medium sequences. Degradation of the copolymers was carried out in pH 7.4 phosphate buffer at 37 °C. Analytical techniques such as 1H NMR, DSC, GPC, and XRD were used to monitor the degradation. Initially amorphous copolymers can remain amorphous during degradation because of the highly random unit's distribution, and equivalent LLA and TMC contents. However, initially amorphous copolymers containing larger amounts of lactidyl units are able to crystallize during degradation because of the presence of relatively long LLA blocks. Insofar, as initially semicrystalline copolymers are concerned, degradation occurs preferentially in the amorphous zones. Therefore, various degradation behaviors and degradation rates can be obtained by varying the chemical composition, chain microstructure, and morphology of PLLA‐PTMC copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3869–3879, 2009

The adsorption of proteinase K on PLLA and PDLA films was studied by CA, surface tension, and microscopic measurements. ESEM clearly shows that proteinase K can irreversibly adsorb on PLLA film. In contrast, no enzyme adsorption was detected on PDLA film under the same conditions. The CA of PLLA film rapidly decreases after immersion in Tris buffer containing proteinase K, whereas that of PDLA remains unchanged. These findings indicate that enzyme adsorption may be a prerequisite for enzymatic degradation of polylactide substrates. Surface tension measurements allow calculation of the average area occupied per proteinase K molecule. The results show that the enzyme molecules exhibit a more compact conformation at higher temperature.