A series of novel copolymers of trans-4-hydroxy-L-proline (Hpr) and (alpha -hydroxy acids [D,L-mandelic acid (DLMA) and D,L-lactic acid (DLLA)I were synthesized via direct melt copolymerization with stannous octoate as a catalyst. These new copolymers had pendant amine functional groups along the polymer backbone chain. The optimal reaction conditions for the synthesis of the copolymers were obtained with 4 wt % stannous octoate at 140 degreesC under vacuum for 16 h. The synthesized copolymers were characterized by IR spectrophotometry, proton nuclear magnetic resonance, differential scanning calorimetry, and Ubbelohde viscometry. The effects of the kinds of comonomers and the comonomer molar ratio on the polycondensation and glass-transition temperature (T-g) were investigated. The T-g's of the copolymers shifted to lower temperatures with an increasing comonomer molar ratio. As expected, the T-g's of the N-Z-Hpr/DLMA copolymers were higher than the N-Z-Hpr/DLLA copolymers, the pendant groups on the monomers (N-Z-Hpr) became larger and more flexible, and the T-g's of the resulting polymers declined. (C) 2001 John Wiley & Sons, Inc.