Synthesis And Study Of Cyclic Polymer Based On Sydnone And Maleimide Click Chemistry

Cyclic polymer doesn't have interaction between each other for lack of end groups,so it has some specific properties compared to linear polymer,It's a special kind of polymer that has topological structure.In recent years,more and more researchers became interested in the relationship between the cyclic polymer and it's property.However,there's only a few reports on the ring closure of cyclic polymer because of the difficult in synthesis,purification and separation.Ring closure between end groups,namely the reaction between the end groups,is a method that converts the linear polymer into cyclic polymer.Now there're three efficient and widely-used methods of ring closure.They're the 'Click,reaction between azide group and alkynyl,'Diels-Alder'(4+2)cycloaddition reaction and the 'Thiol-ene'addition reaction.These reactions often need extreme dilute concentration that we need peristaltic pump to realize.And the use of catalyzer makes the aftertreatment complicated and reduces the products.Thus,we want to find an easier and more efficient method to synthesize cyclic polymer.The writer of this paper uses the 1,3 dipolar cycloaddition reaction between sydnone and maleimide to synthesize hydrophilic Single ring poly ethylene oxide and amphiphilic l-PCL-c-PEO99-l-PCL tadpole-typed polymer.The introduction of the 1,3 dipolar cycloaddition reaction between sydnone and maleimide in the synthesis of cyclic polymer has the following advantages:the concentration of functional group is reduced by half,which reduces side reactions;no catalyzer is used in the reaction,which makes the purification process easier;the concentration of products can be increased by one order of magnitude without special system and there's no requirement for the selection of monomers.Specific research contents are as follows:(1)Graft both ends of polyethyleneglycol that are different in molecular weight,terminate polyethyleneglycol with maleimide group,then use sydnone to react with maleimide,which is a 1,3 dipolar cycloaddition reaction,to synthesize two kind of hydrophilic single ring polymers with different molecular weight.In addition,we discuss how reaction time,reaction temperature and concentration of reactants affect the synthesis of the single ring polymer.The structure and molecular weight of the sample is characterized by 1H NMR,GPC and MALDT-TOF MS.(2)PEO terminated by maleimide group was prepared by molecular design with hydroxyl terminated ethylene oxide as a linear precursor,and then use sydnone to react with maleimide.Followed by the hydroxyl groups of linear precursor and ring polymer,respectively synthesize linear PCL with different molecular weight by ring opening reaction and make the amphiphilic tadpole-typed copolymers l-PCL-c-PEO99-l-PCL(e1-4)and amphiphilic block copolymers PCL-b-PEO99-b-PCL(f1-4).The structure and molecular weight of the sample is characterized by 1H NMR,GPC,and MALDT-TOF MS.Observe its change after self-assemble behavior through TEM and make a preliminary study on the self-assembly behavior.In addition,the thermal properties of linear precursors,monocyclic and tadpole copolymers and block copolymers were studied by DSC.