Preparation of Biodegradable Polymer Copolyesteramides from L-Lactic Acid Oligomers and Polyamide Monomers

Biodegradable copolyesteramide was synthesized from L-lactic acid oligomers and polyamide monomers to improve the properties of poly(lactic acid). The oligomer was synthesized from L-lactic acid using direct polycondensation process at 170 oC, 30 torr for 7 h. p-Toluenesulfonic acid used as a catalyst. From 1H NMR analysis the oligomers have degree of polymerization of ca. 5. The L-lactic acid oligomer (OLLA) was subjected to reacted with ɛ-caprolactam (CLM) with different ratios: 90:10, 80:20, 70:30 and 60:40 using SnCl2·2H2O as a catalyst at 130, 150 and 170 oC pressure 30 torr for 3 h. The synthesized polymers were subjected to thermal property analysis using DSC technique and analyzed the functional groups with FT-IR. It was found that the melting temperature of the polymers increased with increasing amounts of CLM but decreased when the amount of CLM exceeded 30 percent. FT-IR analysis confirmed structure of copolyesteramide comprised of amide ide units and lactate unit.