Synthesis And Characterization Of Cationic Initiator And Polyisobutylene Thermoplastic Elastomer

As technologies in the automotive,aerospace,and medical fields continue to advance,and traditional thermoplastic elastomer materials are increasingly difficult to meet the high performance requirements of these fields,the development of a new generation of thermoplastic elastomer materials is becoming increasingly critical.Poly(styrene-b-isobutylene-b-styrene)triblock copolymer SIBS is a polyisobutylene-based thermoplastic elastomer whose main chain is a fully saturated structure containing only carbon-hydrogen bonds,and the side chains are also free.The double bond,therefore,has excellent thermal oxygen stability,oxidation resistance,acid hydrolysis resistance and enzymatic resistance,and perfectly solves the problem of unsaturation in the conventional thermoplastic elastomer material.However,the industrialization technology of SIBS is still monopolized by foreign manufacturers.In order to meet the domestic demand for new high-performance thermoplastic elastomer materials,this paper explores the SIBS synthetic route with independent intellectual property rights.A bifunctional initiator 5-tert-butyl-1,3-dicumyl ether suitable for positive ion polymerization was prepared by 3 steps of esterification,format reaction and methoxylation.And the product yield is greater than 80%,the purity is greater than 90%,and the target product is obtained by nuclear magnetic resonance detection.On this basis,polyisobutylene and SIBS were successfully synthesized by active controlled cation polymerization.The effects of polymerization time,aging time and solvent composition on copolymerization were discussed.The optimum polymerization conditions were determined:the optimum reaction time of isobutylene is 90 min at-60 degree,the optimum ageing time of the bifunctional initiator and co-initiator was 20 minutes,and the mixed solvent cyclohexane/methyl chloride(volume ratio 60/40)is optimal.The SIBS with the mass fraction of styrene was 21%and 29%.The important properties and molecular weight of the SIBS obtained in the cyclohexane system were all achieved the performance of Japanese commercial products.By soaking the SIBS spline concentrated nitric acid for 12 hours;physiological saline(0.9%NaCl aqueous solution)was immersed for 35 days at room temperature;in the oxidizing mixture(1.63M hydrogen peroxide and 0.1M cobalt chloride hexahydrate)soaked for 40 days at room temperature Stability test,tested the stability of SIBS,and compared with the commercial product poly(styrene-b-butadiene-b-styrene)hydrogenation product SEBS and new polyolefin elastomer POE,and SIBS stability it is good.The trifunctional initiator 1,3,5-tris(2-methoxypropyl)benzene was prepared from trimesic acid by initiator esterification,format reaction and methoxylation three-step reaction,and it was used to initiate the synthesis of a three-arm star polyisobutylene-polystyrene thermoplastic elastomer.The structure of the samples is detected by nuclear magnetic resonance(1HNMR),the 3-arms SIBS were characterized by TG and DSC also.For the testing and characterization of mechanical properties,the overall performance of the three-arms SIBS is comparable to that of the bifunctional system.