Synthesis of biodegradable material poly(lactic acid‐co‐aspartic acid) via direct melt polycondensation and its characterization

Directly starting from L‐lactic acid (LA) and L‐aspartic acid (Asp), biodegradable material poly(lactic acid‐co‐aspartic acid) [P(LA‐co‐Asp)] was synthesized via melt polycondensation. The synthetic conditions, including type and dosage of catalyst, temperature, and time of copolymerization, and influence of molar feed ratio were discussed. The structure and properties of the copolymer were systematically characterized with FTIR, 1H‐NMR, GPC, DSC, and XRD. With the increase of Asp in the feed, [η] and Mw decreased, and the crystallinity of the copolymer disappeared gradually. Compared to the homopolymer, poly(L‐lactic acid) synthesized via melt polycondensation and the copolymer P(LA‐co‐Asp) had a higher glass‐transition temperature (Tg). The copolymer P(LA‐co‐Asp) with Mw of 4400–24300 Da was obtained, which could meet the demand as a drug‐delivery carrier material. Compared to the ring‐opening polymerization of the cyclic intermediates, including lactide, the novel direct copolycondensation method was a cheap and practical method for the synthesis of copolymer P(LA‐co‐Asp) as biomedical materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011