Application Of Thiol-Ene/Yne Click Chemistry In The Synthesis Of Silicon-containing Polymers

As a research focus,chemical reactions with such characteristics as rapid and efficient,mild conditions,simple and convenient are always the goal for researchers to pursue.Fortunately,"click chemistry" is one type of reactions that are of high selectivity,high yields.easy to perform,wide in scope,extraordinary chemical tolerance and mild reaction condition.The click chemistry is shown enormous potential in synthetic chemistry,material sciences,chemicobiology and pharmacology,especially to polymer synthesis.The application of click reation can reduce production cost and avoid the use of toxic heavy-metal catalysts,which is very importance to safety production and environmental protection.Organosilicon compounds have been widely used in aerospace,electrical and electronics,light industry and weaving,machinery,construction material,transportation,medical treatment and health care,because of their unique properties,such as temperature resistance,weather fastness,ageing-resistance,electrical insulation,corrosion resistance,hydrophobicity,flame retardancy,physical inertia,and so on.Other organic polymer materials can not compare with it.The synthetic methods of organosilicon materials are very little comparing with the wide range of organosilicon materials and their application.The increasing demand for materials with tightly controlled structures is an eternal task in polymer chemistry.It is very important that how to simplify reaction steps,design and exploit novel organosilicon compound,extend types and application of silicon products by introduce new synthetic methods or combine with living polymerization technique.In this dissertation,click chemistry combined with other methods is used to design novel organosilicon polymers.In addition,we explore the organosilicon materials with novel properties or difficult to synthesize through other methods.The main contents are as follows:1.A novel and less-costly approach is developed to obtain recyclable self-healing polysiloxane networks based on the thiol-ene reaction and the Diels-Alder(DA).Tetramethy ltetravinylcyclotetrasiloxane(D4Vi)was first modified with furan via a thiol-ene reaction,giving furan-functionalized cyclotetrasiloxane(D1).D1 then reacted with bismaleimide to form thermally dynamic reversible crosslinking linkages via a Diels-Alder(DA)reaction.Thus,cross-linked networks(CNs)were synthesized and their depolymerization through the retro-DA reactions was thoroughly studied.The CNs was found to possess potential applications in recyclable adhesives especially for glass bonding and show strong photoluminescence when irradiated by UV light.The proposed method may be further used in preparation of other self-healing materials,shape-memory networks,and thermo-responsive materials.2.A facile and unique approach with high selectivity was developed to achieve novel polysiloxanes containing sulfone groups from sulfur-bridged cyclosiloxanes monomers without the use of catalysts,instead,sulfur oxidation was performed.The sulfide oxidation reaction can induce ring-opening polymerization of the cyclosiloxanes through cleavage and rearrangement of Si-O-Si bonds.Sulfur-bridged functionalized cyclosiloxanes were first synthesized via a facile thiol-ene reaction using cyclosiloxane with two commercially available thiol monomers.These functionalized cyclosiloxanes are further oxidized into sulfone-containing siloxanes.meanwhile,the cleavage and rearrangement of Si-O-Si bonds induced by the oxidation reaction lead to ring-opening polymerization of the sulfone-containing siloxanes.The work described here provides a significant advancement in the field of chemistry by introducing a novel polymerization method to achieve new polysiloxanes.It was demonstrated for the first time that a commercially available oxidant,Oxone,can be used as an accelerant to induce the ring-opening of sulfur-bridged cyclosiloxanes.This finding will present novel insights to synthesize new polysiloxanes.3.To study the cleavage and rearrangement of Si-O-Si bonds in the synthesis of novel polysiloxanes containing sulfone groups from the oxidation of sulfur-bridged cyclosiloxanes monomers,we designed contrast experiment and calculated the molecular orbital function.The comparison of Si-O-Si chain backbone and side chain structure from different sulfur-bridged organosilicon compound is used for the researching of the relationship between the structures of reactants and products.The sulfur-bridged POSS and sulfone-containing POSS were characterized by NMR and GC-MS.According to the calculated results of the molecular orbital function of the sulfur-bridged functionalized cyclosiloxanes before and after oxidation,we deduced the probable mechanism for oxidation polymerization.The oxone-assited Si-O-Si bond cleavage and rearrangement reactions may be widely used in the synthesis of other sulfone-containing polysiloxane or novel siloxane architecture compounds,and understanding of the mechanism of cleavage and rearrangement of Si-O-Si bonds in oxidation process provides a new angle about the polymerization process.4.Thiol-ene and thiol-yne click reactions are explored as simple and efficient routes to the rapid production of diverse functional silanes and sulfur-bridged silylated polymers,and unsaturated bonds containing silylated polymer were further post-functionalized by thiols.The structures and photophysical properties of the obtained products have been throughly characterized by FT-IR.NMR,LC-MS and fluorescence spectrophotometer.The reaction process between ethynyltrimethylsilane and thiol was monitored through the NMR to study the isomerization phenomenon.The optical and photophysical properties of the obtained products have been throughly characterized by DSC,TGA and fluorescence spectrophotometer.Further.2-((3-(trimethylsilyl)propyl)thiol)succinic acid(Te-3)was selected as a starting molecule to coordinate with lanthanide ions,and nanorods formed by self-assemble from the coordinate complex and shown strong luminescence.We observed the forming process of nanorods and speculated the possible forming-mechanism.The novel aggregation phenomenon of Te-3 complex was characterized and discussed,and the research will be greatly beneficial to understand and prepare metal-organic complex nanomaterials.