Synthesis and characterization of degradable copoly( trans ‐4‐hydroxy‐ L ‐proline/ϵ‐caprolactone)

The melt polycondensation reaction of N ‐protected trans ‐4‐hydroxy‐ L ‐proline ( N ‐Z‐Hpr) and ϵ‐caprolactone (ϵ‐CL) over a wide range of molar fractions in the feed produced new and degradable poly( N ‐Z‐Hpr‐ co ‐ϵ‐CL)s with stannous octoate as a catalyst. The optimal reaction conditions for the synthesis of the copolymers were obtained with 1.5 wt % stannous octoate at 140°C for 24 h. The synthesized copolymers were characterized by IR spectrophotometry, 1 H NMR, differential scanning calorimetry, and Ubbelohde viscometry. The values of the inherent viscosity (η inh ) and glass‐transition temperature ( T g ) of the copolymers depended on the molar fractions of N ‐Z‐Hpr. With an increase in the trans ‐4‐hydroxy‐ N ‐benzyloxycarbonyl‐ L ‐proline ( N ‐CBz‐Hpr) feed from 10 to 90 mol %, a decrease in η inh from 2.47 to 1.05 dL/g, and an increase in T g from −48 to 49°C were observed. The in vitro degradation of these poly( N ‐CBz‐Hpr‐ co ‐ϵ‐CL)s was evaluated from weight‐loss measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3176–3182, 2003