Structure Regulation Of Polymers Via Chain Shuttling Polymerization And Consecutive Multicomponent Reactions

Synthesis of complex topologies and sequence-controlledpolymers is one of the hotspots in the field of polymer chemistry.Chain shuttling polymerization and multicomponent reaction are new methods for synthesizing polymers with different topologies and sequence structure.However,the current chain shuttling polymerization methodcan only copolymerize olefin monomers.The multicomponent reaction,although due to its efficient combination of more components in one-pot,is used in the synthesis of the sequence-defined polymers,but compared to the monomer components of the biomacromolecule(for example,the protein consists of 20 different amino acids),the number of monomers is still few,and the complexity and functionality of the resulting sequence-defined polymers are still insufficient.In addition,the multicomponent reaction has not been widely used in the synthesis of polymers with different topologies.In this dissertation,Iconstructed a chain shuttling polymerization system between different kinds of monomers to synthesize copolymers with novel structure,which was difficult to obtain by the existing method.And two multicomponent reactionsare combined in one pot to synthesize sequence-defined polymerswith more complex structure.I also extended the application of multicomponent reactions in the synthesis of polymerswith different topologies.Including the following four parts:1.Ihave developed a chain shuttlingpolymerization system with trithiocarbonate as a chain shuttlingagent.The trithiocarbonate can be simultaneously used as a RAFT chain transfer agent for vinyl monomer and an initiator for anionic ring-opening polymerization of propylene sulfide.Therefore,in the medium of the trithiocarbonate,the growth chain can shuttle between the RAFT polymerization of vinyl monomer and the ring-opening polymerization of propylene sulfide.The chainshuttlingbehavior induced by the trithiocarbonate can combine two different segments(the segments of vinyl monomer and the segments of propylene sulfide monomer)to form a copolymer chain.With this new polymerization system,the two monomers,which are very difficulttobe copolymerized via existing methods,can be easily copolymerized into a polymer chain.By adjusting the initiator,catalyst and monomer concentration,we can change the shuttlingbehavior to control the chain microstructure to form block,multiblock and gradient copolymers with different segments.2.We design anamine-thiol-ene three-component reaction based on the ring-opening of thioester and thiol-Michael Addition.Methacrylates,thioesters and primary amine compounds constitute the starting reactants of this three-component reaction.The primary amine can not react with the double bond of methacrylate,but it allows the ring-open of 5-membered cyclic thioester to release athiol group.Thethiol groups produced in situ can react with the double bond of methacrylatein alkaline conditions via high-efficient Michael Addition reaction to generate a complex product.Due to the high efficiency,the multicomponent reaction can be used to synthesizea series of high molecular weight sequence-controlled polymer.3.We combine the amine-thiol-ene three-component reaction developed in the second part with the efficient copper-catalyzed azide-yne-amine three-component reaction to design a new strategy for the preparation of sequence-controlledpolymers with complex structures.The two multicomponent reactions were carried out by a special monomer propargyl methacrylate.The double bond of propargyl methacrylate(A),thiolactone(B)and the bifunctional primary amine(C)are reacted viathe amine-thiol-ene three-component reaction to form an ABCBA sequence compound with two yne groups.ABCBA sequence compound,sulfonyl azide(D)and p-phenylenediamine(E)are polymerized by azide-yne-amine three-component reaction to obtain high molecular weight polymers with a DABCBADE sequence.4.On the basis of the third part,Icombinedthe amine-thiol-ene three-component reaction with copper-catalyzed azide-yne-amine three-component reaction to design a new strategy for the preparation of various polymers with complex and diverse topologies.Secondary amines do not cause the thioester to open the ring and do not reactwith methacrylate,but could be involved in the copper-catalyzed azide-yne-amine three-component reaction.Polymers with linear,hyperbranched and core-shell structurescould be obtained by use of an amine-based monomer having both primary and secondary amines and propargyl methacrylate monomers having both alkenyl and alkynyl groupsthrough amine-thiol-ene three-component reaction and azide-yne-amine three-component polymerization.