Synthesis Of Various Structural Glycopolymer By RAFT Polymerisation And Application

Glycopolymers are important component in organisms.Glycopolymers can be used as structural materials as well as metabolites in organisms,such as cell walls,cellulose,starch and glycogen.The complex structure of glycopolymer can affect biological processes involving signal transmission and immune response in organisms,and is related to the pathogenesis of many diseases,such as metabolic,neoplastic,and neurological diseases.Therefore,the research on glycopolymer synthesis methods and glycopolymer structures is of great significance to chemistry,biology,and medicine.This paper synthesizes sugar monomers with various structures,and then prepares multiblock,hyperbranched and branched/cyclized hybrid polymannose via reversible addition-fracture transfer（RAFT）polymerization.Finally,the effect of glycopolymer structures on the binding behavior of model proteins was studied.Chapter I:Progress of glycopolymers.Chapter II:Linear macromolecular chain transfer agent（CTA-L）was synthesized by Huisgen 1,3-dipolar cycloaddition reaction with polyethylene glycol and small molecular chain transfer agent（CTA-N₃）as raw materials.Also,the best reaction conditions of CTA-L were screened out.Then,using RAFT polymerization,the linear multiblock polymannose CTA-L-Ma M was prepared with CTA-L and 6-O-methacryloyl mannose（Ma M）as raw materials.The results showed that the molecular weight distribution of CTA-L-Ma M is narrow owing the average effect of random breakage and addition of molecular chains.The online monitoring data of gel permeation chromatography directly confirmed this view,and the potential reaction mechanism was also introduced.The application study of CTA-L-Ma M showed that the multiblock polymer and linear polymer kept the same inhibition effect on the fibrosis of lysozyme in egg white.In addition,CTA-L-Ma M can be self-assembled into vesicles,which makes CTA-L-Ma M have a certain application prospect in the field of load transport.Chapter III:Branched macromolecular chain transfer agent（CTA-P）was synthesized by Huisgen 1,3-dipolar cycloaddition reaction of tripropargylamine with CTA-N₃.Then,using RAFT polymerization,the hyperbranched polymannose CTA-P-Ma M was prepared with CTA-P and Ma M as raw materials.The results showed that the molecular weight distribution of CTA-P-Ma M is narrow owing the average effect of random breakage and addition of molecular chains.By applying the average effect in RAFT polymerization mediated by macromolecular chain transfer agents,the research in this chapter not only enriches the types of these agents,but also achieves precise control over the structure of hyperbranched glycopolymer.CTA-P-Ma M showed obvious advantages in inhibiting fibrosis of lysozyme in egg white,which was mainly attributed to the glycoside cluster effect brought by hyperbranched structure.In addition,cytotoxicity experiments showed that CTA-P-Ma M also had good biocompatibility.Chapter IV:Branched/cyclized hybrid glycopolymer（HGP（Man EMA-co-IM））was prepared by RAFT polymerization/Click reaction by using 2-（α-D-mannopyranosyloxy）ethyl methacrylate（Man EMA）and 2-isocyanatoethyl methacrylate（IM）as monomers.The possible reaction mechanism was pointed out in this paper,which revealed the molecular weight and branching degree of glycopolymer were controlled by the reaction conditions.The formation of cyclic structure in hyperbranched polymers is inevitable.In HGP（Man EMA-co-IM）structure,the trithioester groups form cyclic structures or connecting end groups.By adding sodium borohydride and hydrogen peroxide,the reversible switching of intramolecular cyclic structure can be realized without affecting the branched unit structure.By studying the interaction with concanavalin A,the effects of molecular weight and branching degree on glycoside cluster effect were discussed.Chapter V:Halloysite nanotube-glycopolymer composites（HNTs-HGP）series were obtained by using RAFT polymerization/Click reaction to modify polymannose into halloysite nanotubes（HNTs）through three synthetic routes.By optimizing the reaction conditions and ways,the highest grafting ratio was 46.7%.The binding behavior of polymannose modified HNTs with concanavalin A was studied by TGA and TEM.It is proved that the modified hallowite nanotubes can bind to concanavalin A,and it has potential application prospects in specific enrichment and targeted drug delivery.The cyclic structure of grafted glycopolymer on HNTs-HGP was proved to have a certain antibacterial effect by Escherichia coli,and HNTs-Ag was obtained by anchoring silver nanoparticles on HNTs-HGP with rich trithioesters on HNTs-HGP to enhance its antibacterial effect.