Synthesis And Properties Of Polythioethers With Functional Groups Synthesized By Thiol-ene/yne Click Chemistry

Recently,precise control of the backbone structure and hetero-functional groups within the synthetic polymer is still a big challenge in the field of polymer chemistry.Thiol-ene/yne click polymerization is a new type of click polymerization,which has attracted extensive attention from the scientific community due to its mild reaction conditions,simple operation,easy access to raw materials,high yield and high selectivity,and has been applied to the preparation of polythioethers?PTEs?with different structures and functions.In this thesis,a series of functionalized PTEs with linear,hyperbranched and crosslinked structures were facilely synthesized via photo-initiated thiol-ene/yne click polymerization under mild reaction conditions.Firstly,a new family of hetero-functional polythioethers with alternating hydroxyl and epoxy groups were facilely synthesized via photo-initiated thiol-yne click?co?polymerization under mild reaction conditions.Their chemical structures and hetero-functional group density could be finely tuned by adjusting the feeding mole ratios.As the evidence of NMR and GPC tests,either the molecular weight or the hetero-functional group density depended greatly on the S-H bond cleavage energy of dithiols which could be predicted by theoretical calculation,using the DFT B3LYP and the QCISD methods.This paper provides access to a wide range of new materials with a specific structure and plentiful alternating hetero-functional groups.Moreover,it unveiled and highlighted the role of S-H bond cleavage energy of dithiols during the process of step-growth thiol-yne click?co?polymerization.Secondly,three cationic polythioethers?CPTEs?with hyperbranched topologies are well-designed and facilely synthesized via an all-click chemistry strategy?including thiol-ene and epoxy-amine additions?.These as-prepared CPTEs were found to exhibited outstanding antibacterial activity against Escherichia coli?E.coli?and Staphylococcus aureus?S.aureus?with minimum inhibitory concentrations?MICs?against E.coli of 7.3,14.6 and 14.6?g mL^-1,and against S.aureus of 14.6,29.2 and 29.2?g mL^-1,respectively.The antibacterial activity is coincident with their degree of branching?DB,their DB values of 0.81,0.48 and 0.27?,which is mainly attributed to the inherent three-dimensional structure.The present strategy reveals the relationship of polymer topology and antibacterial activity,providing a novel possibility for designing and/or synthesis of high-efficiency antibacterial agents.Base on that,the micron-sized porous polymer microspheres?PPMs?with epoxy groups were prepared by thiol-yne click suspension polymerization.The pore size of PPMs was determined by mercury injection instrument,most of which were distributed in 20²5?m and the porosity was 42.24%.Then CPTEs was grafted on PPMs surface by epoxy-amine click reaction.The chemical structure,thermal properties and morphology of PPMs before and after modification were studied by FT-IR,DSC and electron microscopy?SEM?.The characterization data demonstrate the successful preparation and modification of PPMs.