Study On The Synthetic Functionalized Sulfur-Containing Polymers

With the increasing demand for multi-functional materials,the main chain sulfur-containing polymers have attracted more and more attention.It is well known that the introduction of sulfur atoms into the polymer chain can improve various properties of the corresponding polymer,such as optical performance,heat resistance stability,and the ability to adsorb heavy metals.As two important main chain sulfur-containing polymers,various methods for synthesizing polymonothiocarbonate and polythioester have been developed in succession.Among them,due to its simple synthesis method,high efficiency,and the resulting polymer structure is diverse and controllable,the alternating copolymerization of alkylene oxide with carbon-based sulfur（COS）and episulfide and thioanhydride produces the corresponding polymonothio Carbonate and polythioester stand out from many synthetic methods and have received more and more attention.However,the optical properties of the produced polymonothiocarbonate and polythioester still cannot meet the application requirements of these materials in the field of precision optics.The reason is that the synthetic polythiocarbonate and polythioester have a single topological structure,which leads to the material’s performance not being very prominent.Therefore,how to improve the optical and thermodynamic properties of such materials is a challenging and significant topic.We will solve the shortcomings of optical and thermodynamic properties of these two types of sulfur-containing materials by synthesizing polythiocarbonate with topological isomerism and polythioester with functionalized sites.The details are as follows:（1）In this dissertation,through the screening of the catalytic system,the ternary polymerization of epoxy cyclohexane（CHO）/COS/CO₂ was realized by using the catalytic system of binuclear biphenyl metal aluminum complex.The corresponding polymer structure was characterized by ¹H-¹H COSY spectrum,¹³C-NMR spectrum and GPC,and the resulting polymer was determined to be a terpolymer of carbonate and thiocarbonate randomly distributed.The content of carbonate and thiocarbonate units in the resulting polymer chain has been maintained to increase in proportion with time through tracking reaction and in-situ infrared monitoring reaction.And the ratio of carbonate and thiocarbonate in the resulting terpolymer can be adjusted by changing the pressure of carbon dioxide.The optical properties of the ternary telomers obtained with different proportions of carbonate and thiocarbonate units were found,the optical properties of telomers are significantly improved compared to pure polycarbonate and polythiocarbonate.And the ternary copolymer with carbonate/thiocarbonate ratio of 1:1 has the best optical performance,its refractive index can reach1.501（25 ^oC）,and Abbe number can be as high as 48.6（25 ^oC）.（2）Based on the report of a new method for preparing polysulfides by copolymerization of thioanhydride and cyclothioalkanes,polysulfides with double bonds in the side chain were synthesized in this paper.the polymer is an amorphous material and its glass transition temperature（T_g）is 94.3 ^oC.At the same time,it also designed to use the Diels-Alder reaction to design and synthesize the anhydride monomer to achieve the copolymerization reaction with propylene oxide.Ring structure,the test found that the polymer is a crystalline material with a melting temperature（T_m）of up to 118.6 ^oC,which further improves the thermal stability of the polythioester.