D,L-lactide was prepared from D,L-lactic acid by means of polymerization and depolymerization at low vacuum level.Morpholine-2,5-dione(MD) was synthesized from the cyclization of chloroacetyl glycine which was made from chloroacetyl chloride and glycine in the basic condition.A novel copolymer(PLAMD) with D,L-lactide(D,L-LA) and morpholine-2,5-dione(MD) was synthesized using stannous octoate as initiator,and characterized with FT-IR and 1HNMR.The biocompatibility of PLAMD and PLA was investigated by MTT and microscope.The results show that amino acid is introduced into PDLLA main chain.PLAMD has better cell affinity than PLA,so it is a promising biomaterial.
With sol-gel method,nanometer La-Ti composite oxides were prepared.By means of atomic force microscope,the surface pattern,particle size distribution and specific surface area were studied.The newly prepared nanocrystals of La-Ti composite oxides were used as the catalysts to catalyze the dehydration of external compensated lactic acid to lactide.The lactide product was measured by polarimeter and micropolariscope.The results demonstrate that the ratio between D-lactide and L-lactide will not be equal to 1-1 if nanocrystals of La-Ti composite oxides are used as the catalysts,which implies,that nanocrystals of La-Ti composite oxides may be potential catalysts with a good selectivity.
