High molecular weight biodegraded poly(lactic acid-glycolic acid-e-caprolactam) copolymer: direct polycondensation of lactic acid, glycolic acid and ε-caprolactam using Sn(II)-organic anhydride as catalysts

摘要

High molecular weight poly(lactic acid-glycolic acid-ε-caprolactam) (PLGC) copolymer was synthesized by simply heating a mixture of DL-lactic acid aqueous, glycolic acid, and ε-caprolactam (CLM) using organic anhydride and tin (II) chloride dihydrate (SnCl{sub}2·2H{sub}2O) or metal powder as catalysts without organic solvents. At the same time, in order to investigate the effects of the structure of amino acid on the properties of copolymers, poly(lactic acid-glycolic acid-glycine) (PLGG), poly(lactic acid-glycolic acid-L-alanine) (PLGA-1), poly(lactic acid-glycolic acid-β-alanine). (PLGA-2), poly(lactic acid-glycolic acid-γ-aminobutyric acid) (PLGA-3), and poly(lactic acid-glycolic acid-L-phenylalanine) (PLGP) were synthesized under the same conditions, respectively. The structure of PLGC was confirmed by FT-IR and NMR spectra. The average molecular weight of PLGC was determined by the Ubbelohde model (corrected by 1{sup left}H-NMR end-group analysis). The results indicated that compounds of organic anhydride and SnCl{sub}2 · 2H{sub}2O were active, and the highest average molecular weights could achieve 9800 Da. The thermal properties were evaluated using differential scanning calorimetry (DSC) and the results indicated that the glass transition temperatures (T{subg}gs) of polyesteramide increased with the increase in the carbon atom numbers between carboxyl and amino-groups of amino acid. The T{sub}gs were higher when α-carbon atom of amino acid linked with a "rigid" group than a "soft" group. The solubility and hydrolytic degradation of PLGC copolymers were investigated.