Synthesis And Exploration Of Poly (Lactide-lactide)-Poly (Glutamic Acid Benzyl Ester)block Copolymers

Over the past two decades,poly(lactide-lactide)(PLGA)has been among the most promising biodegradable polymer materials for drug delivery and tissue engineering,PLGA have been widely used in the delivery of small molecule drugs,proteins,and other macromolecules,showing great research value and commercial value with good biocompatibility,degradable,adjustable mechanical properties.Many years ago,it has been used as medical excipients by the US FDA.People have been working on the research of PLGA and its block copolymers in recent years.The polyglutamic acid benzyl ester(PBLG)has a very good prospect in the field of drug controlled release system,tissue engineering and other fields as a sustained-release drug carrier.In this paper,the synthesis of PLGA was investigated.A series of poly(lactide-lactide)were prepared,glycolide and lactide as the monomers,isopropanol as the initiator,stannous octoate as the catalyst and toluene as the solvent.The influence of the number of crystallization times,reaction time and solvent amount on the polymerization reaction was found,the most complete copolymer with a molecular weight approximately consistent with that of the design,with a narrow molecular weight distribution has been synthesized when the monomers were recrystallized three times,the reaction temperature was 120~oC.,the reaction time was 48 h,and the solvent amount was three times the monomer mass.The synthesis of PBLG based on the principle of ring-opening polymerization of BLG-NCA.It has been found that when the benzyl glutamate NCA was recrystallized three times and reacted 6 days at room temperature,we have achieved expected degree of polymerization.Finally,a block copolymer PLGA-b-PBLG is formed by the reaction of PLGA-COOH,which activates the back-end carboxyl group,and PBLG through a macromolecular coupling reaction.PLGA-b-PBLG have excellent properties such as biodegradability,biocompatibility,and polymerization controllability,it will broaden the application of drug delivery systems,genetic engineering transmission,tissue engineering,and new antibacterial materials,has the magnificent development prospects.