Study On The Preparation Of Carbon Dioxide-based Elastomers Catalyzed By Bimetallic Catalysts

A large amount of carbon dioxide is released in human daily activities,breaking the carbon balance in the atmosphere,which has evolved into frequent natural disasters caused by the intensification of the greenhouse effect.My country is committed to achieving a carbon peak in 2030.On the one hand,it needs to reduce carbon emissions from the root,and on the other hand,it needs to fix carbon dioxide to slow down the rate of carbon emissions.In recent years,the use of carbon dioxide and epoxy compounds to synthesize degradable polycarbonate plastics has been industrialized by a chemical method.However,there are few reports on the use of carbon dioxide to prepare elastomers,mainly due to the higher glass transition temperature of polycarbonate.In the early stage,the research group adopted anion coordination method and used a rare earth three-way catalyst to catalyze the copolymerization of carbon dioxide and long-chain branched allyl glycidyl ether(AGE)to prepare a carbon dioxide-based copolymer with a glass transition temperature of-35?.However,the excessively high content of double bonds in the molecular structure leads to over cross-linking,which causes the material to become hard and brittle,which cannot meet the requirements of elastomer materials.In this paper,firstly,based on the previous binary copolymerization of CO2-AGE,the second epoxy compound monomer containing long chain branches,1,2epoxyhexane(1,2-HO)was introduced from the perspective of molecular design to destroy the regularity of the molecular chain and regulate the double bond content.In the selection of the catalytic system,a zinc-cobalt(?)double metal cyanide complex catalyst(Zn-Co? DMCC)was selected.The main contents of the paper are as follows:In the second chapter,in the first place the catalytic effect of the bimetallic catalyst Zn-Co? DMCC on the binary copolymerization system of AGE and CO2 was studied,and the CO2-AGE binary copolymer was synthesized.In order to ensure the degradability of the polymer,the content of polyether segments in the molecular structure should be less than 20%,and it is finally determined that 75? and 4MPa are the best reaction temperature and reaction pressure.On the basis of Chapter 2,under the optimal reaction conditions,two epoxy monomers and carbon dioxide were introduced to carry out a ternary copolymerization reaction,and finally CO2-AGE-1,2-HO copolymer was successfully prepared.Through gel permeation chromatography(GPC)test,the number average molecular weight of the synthesized carbon dioxide-based elastomer can reach 76.8kg/mol-1.Through the characterization of infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy,the effect of introducing different ratios of 1,2-HO on the structure of the copolymer was studied.Through calculation,when the feed ratio of the two epoxy resins is 1:1,the ratio of the obtained polycarbonate to the polycarbonate is 90.7%,the monomer conversion rate is 51%,and the catalytic efficiency reaches 1628 gpolymer/gcatalyst.In addition,the proportion of double bond content in the copolymer structure is reduced from 19.3 to 8.9 under this ratio,and its Tg is-32.6?,which meets the performance requirements of elastomer materials.After cross-linking by peroxide,the cross-linking density can be significantly reduced.Without the introduction of reinforcing fillers,the tensile strength is 0.5 MPa,and the elongation at break reaches 339%.