Synthesis Of Functional Polymers From Carbon Dioxide And Sulfur

The reuse of waste is a hot topic in modern society.Carbon dioxide,a greenhouse gas,leading to the continuously increase of earth temperature and global warming.Copolymerization of carbon dioxide and expoxide to produce aliphatic polycarbonate materials is the commonest way to turn waste into treasure.Sulfur,as a by-product of hydrodesulfurization in petrochemical industry,produced tens of million tons per year,but its application is very limited.The inverse vulcanization process provides a new way for the synthesis of sulfur-rich polymers.Therefore,the reuse of waste is imminent.In this paper,waste CO₂and elemental sulfur are used as the initial raw materials to form functional polymers by copolymerization with different monomers to achieve the purpose of waste reuse.The main research includes three aspects.Firstly,aliphatic polycarbonates with double bonds in the side chain were synthesized using CO₂as the main raw material.Then,they were functionalized and modified by the thiol-ene click reaction to synthesize photosensitive polymer materials.Next,the reuse of waste sulfur was studied.Inspired by the reverse vulcanization process,stable sulfur-rich polymers were prepared by the copolymerization of lipoic acid and sulfur,the degradation properties were also studied.However,the solubility of the polymer was poor.Finally,based on the copolymerization of sulfur and lipoic acid,the third monomer styrene was added to improve the solubility of polymer.1.The functional modification and photosensitivity of aliphatic polycarbonate synthesized from waste CO₂were investigated.The results show that the content of cinnamoyl can be effectively controlled by adjusting the feed ratio in the initial synthesis of polycarbonate and click reaction time.When the feed ratio of propylene oxide（PO）and allyl glycidyl ether（AGE）is 2:3,the content of AGE in the obtained polycarbonate PPCAGE can reach 48.1%.Then,after 1 h of click reaction,the polymer c_26.1-PPCAGE with the M_nof 9.0 kg·mol^-1and the PDI of 1.06 can be obtained,the structure of the obtained polymer is characterized.The reversible kinetics of cross-linking and decrosslinking under the UV irradiation of 365 nm and 254 nm were explored.It was found that the reversible cycle number of the polymer under above condition can reach 4 times,indicating that the material has good chemical stability.2.The degradable sulfur-rich polymer was synthesized by copolymerization of lipoic acid and waste sulfur.Firstly,the optimal conditions of the polymerization were explored.It was found that when the feed ratio of S and TA was 2:1,stirring at 110°C for 12 h,the sulfur-rich polymer with stable structure could be obtained and the M_nis2.0 kg·mol^-1and the PDI is 1.00,the polymer could be degraded in the mixed solution of Na OH and methanol.the effects of reaction material ratio and reaction time on the polymerization were explored,and the structure of the obtained polymer was characterized.The results show that the content of segment in the obtained polymer can be controlled by adjusting the feed ratio and reaction time.In the degradation experiment,the degradation rate can be controlled by adjusting the ratio of Na OH to methanol.3.The terpolymerization of waste sulfur,lipoic acid and styrene was investigated,and the purpose of improving the solubility of binary sulfur-rich polymer was achieved.Firstly,the optimal conditions of terpolymerization were explored.It was found that when the feed ratio of S,thioctic acid and styrene was 0.5:1:1,stirring at 130℃for 6 h.The sulfur-rich polymer with good solubility and stable existence can be obtained and the M_nis 177.6 kg·mol^-1and the PDI is 1.56,in which the conversion of styrene can reach 67.9%.At the same time,the effect of reaction time on the polymerization was explored,the structure of the polymer was characterized.The results showed that the content of chain segment in the obtained polymer can be controlled by adjusting the reaction time.The solubility of the terpolymer was greatly improved compared with the binary copolymer.