Study On Copolymerization Of γ-Benzyl Ester Of L-Glutamic Acid And L-Alanine

Poly(amino acids) are a kind of biodegradable polymer materials with low toxicity, excellent biocompatibility, biodegradability and bioabsorbability in vivo. They are very widely used, especially in pharmaceutical and biomedical areas such as drug delivery systems and tissue engineering.Reaction of copolymerization based on L-glutamic acid and L-alanine was systematically studied. The γ-carboxyl was protected by L-glutamic acid reacted with benzyl alcohol, which could produce the γ-benzyl ester of L-glutamic acid. The excess of gaseous phosgene passed into the suspensions of L-alanine and the γ-benzyl ester of L-glutamic acid respectively at 0℃ and then heated to 30℃ slowly. The N-carboxyanhydride of γ-benzyl ester of L-glutamic acid and N-carboxyanhydride of L-alanine was synthesized, and the IR spectrums show that reactantive products are γ-benzyl ester of L-glutamic acid, L-carboxyanhydride of γ-benzyl ester of L-glutamic acid and N-carboxyanhydride of L-alanine. In addition, the attempt to use trichloromethyl instead of phosgene simplifed experiment apparatus and shortened reaction time to a great extent.Copolymer of N-carboxyanhydride of γ-benzyl ester of L-glutamic acid and N-carboxyanhydride of L-alanine was prepared in the way of ring-opening in nitrobenzene with triethylamine as initiator at 40℃ and the structural characteristics of copolymer were illuminated through solid state ¹³C NMR. The intrinsic viscosities of the copolymers were measured in dichloroacetic acid at 30℃ with an Ubblohd capillary viscometer. The copolymers were reacted with hydrochloric acid(0.2 M) for removing benzyl ,filtered and dried under vacuum after being filtered. The obtained copolymers which didn't contained benzyl were dissolved in sodium hydroxide solution (V_acetone :V_water =1:1) by heating. Superfluous hydrochloric acid(0.2 M) was added into the above solution and dried in the help of rotary evaporator and the obtained polymers were dissolved again in pyridine. The mole ratios of two units in...