The Preparation Of Water-soluble Graft Polymer Through Post-polymer Modification Of Polythioester

Post-Polymer Modification is a widely used way on producing functional polymer which could not synthesized by directly polymerization,on which usually polymerize the monomer first,then modificate the reactional group.By using Post-Polymerization Modification,the reaction condition is milder,and the quantity is easier to control.So the Post-Polymer Modification is a very effective and important way to produce functional macromolecular.Thioester is a widely used functional group in synthesis chemistry because of its high reactivity on Native Chemical Ligation,which based on thioester is nowadays widely used on protein synthesis and most of them are on connecting two proteins.Native Chemical Ligation usually starts with the exchange of polythioester and outer thiol,and then exchange the thioester group and amino group inside the molecular to achieve the reaction.Native Chemical ligation is always praised by mild reaction condition and high conversion.But until now,we have seldom reports on applying Native Chemical Ligation on artificial polymer modification.According to these,in this paper,we firstly designed thioester monomer,and then produced a kind of water-soluble polythioester by radical copolymerization with other monomers.By using the polythioester as the main chain,amino acid as the reaction group,we firstly accomplished grafting PEG to polymer main chain through Native Chemical Ligation and produced a water-soluble graft polymer.1.By working on three ways of introduce thioester into polymer:ATRP,ROP and the polymerization of thioester monoer,the results showed polymerization of thioester monomer is the most successful and effective way,and also applicable to other(methyl)acrylate monomers.In this study,we synthesized two thioester monomers,which were thioglyceryl acrylate and thioglyceryl methacrylate.Then copolymerized them respectively with NIPAM and DMAA in different ratio by 5%AIBN radical polymerization in toluene solution,and produced four kinds of water-soluble copolymers from ratio 17:83 to 71:29.2.We synthesized two kinds of branches,which were PEG-cysteine and PEG-alanine.With adding TCEP and Na2CO3 aqueous solution as pH adjust agent to adjust the pH to 7,we successfully synthesized the water-soluble graft polymer by the Native Chemical Ligation of polythioester.Through measuring the products every step,we found that it was more effective while using cysteine as the reaction group comparing to alanine.