Synthesis And Characterization Of Biodegradable Poly (ester-amide)s Containing L-amino Acid Residues

In order to improve the hydrophilic and degradation of poly(s-caprolactone)[PCL], four amino acids (L-alanine, L-leucine, L-glutamic acid and L-lysine) were introduced into PCL, and four poly(ester-amide)s containing L-amino acid residue were synthesized.To impart the L-amino acide residues to poly(p-dioxanone)[PPDO] and PCL, the preparation of intermediate or oligomer was critical. The ring-opening of PDO and CL proceeded by the primary amino group of amino acid sodium, and four depsipeptides were prepared by subsequent acidification. Optimal conditions of this reaction have been studied, and the structure of depsipeptide was confirmed by1H-NMR and FT-IR. At140℃when the feed ratio of amino acid sodium and CL was1:4, no amino acid was left, which contributed to the preparation of amino acid-terminated PCL with narrow molecular weight distribution. The1H-NMR and FT-IR spectra indicated that the amino acid sodium effectively initiated the ring-opening of PDO and CL, and the depsipeptides were prepared. By controling the feed ratio of amino acid sodium and CL, L-leucine-terminated-PCL and L-alanine-terminated-PCL oligomers with different molecular weight were prepared.Based on that, four PCL oligomers with different amino acid residue were prepared, and the structure was confirmed by1H-NMR and GPC. Four poly(ester-amide)s were synthesized by using these oligomers as macromonomers and HDI as chain extender. The poly(ester-amide)s were characterized by FT-IR, water contact angle measurement, water uptake and hydrolysis experiment. The results indicated that the hydrophilic of the amino acid-derived PCL was improved, and that the hydrophilic and the biodegradation rate of the poly(ester-amide) with L-lysine residue were highest.