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采用烯烃交叉易位反应,在Grubbs二代催化剂和含有功能基团的链转移剂作用下,研究了工业级高分子量顺丁橡胶的降解以及高附加值遥爪型丁二烯低聚物的制备.涉及的链转移剂主要是轴对称的顺丁烯类衍生物:顺-1,4-二氯-2-丁烯(DCB)、顺-1,4-二乙酰氧基-2-丁烯(DAB)、马来酸二甲酯(DMM)、马来酸二乙酯(DEM).产物的分子量(Mn)和分子量分布指数(PDI)通过凝胶渗透色谱仪(GPC)测定,产物的分子链段结构和组分通过红外光谱(FTIR)、核磁共振氢谱(1H-NMR)以及高效液相色谱-质谱联用(LC-MS)表征.实验结果表明,通过引入不同的链转移剂,控制顺丁橡胶/链转移剂、顺丁橡胶/催化剂的摩尔投料比以及反应时间,可以有效控制低聚物的Mn和PDI,其Mn变化范围为230~4800,PDI变化范围为1.09~2.82.进一步研究发现,在一定反应条件引入DAB,可以逐一断裂顺丁橡胶的主链,获得丁二烯重复单元仅为1的小分子新结构.
The degradation of industrial grade high molecular weight butadiene rubber and the preparation of high value-added telechelic butadiene oligomer were studied by the cross-metathesis reaction of alkene under Grubbs second-generation catalyst and functional group-containing chain transfer agent The chain transfer agents involved are predominantly axisymmetric maleic derivatives: cis-1,4-dichloro-2-butene (DCB), cis-1,4-diacetoxy-2-butene (DAB), dimethyl maleate (DMM), diethyl maleate (DEM) The molecular weight (Mn) and molecular weight distribution index (PDI) of the product were determined by gel permeation chromatography (GPC) The molecular chain structure and its components were characterized by FTIR, 1H-NMR and LC-MS. The experimental results show that by introducing different chain transfer agents , Controlling the molar feed ratio of butadiene rubber / chain transfer agent, butadiene rubber / catalyst and the reaction time can effectively control the Mn and PDI of the oligomers, with Mn ranging from 230 to 4800 and PDI varying from 1.09 to 2.82 The further study found that the introduction of DAB under certain reaction conditions can break the main chain of the butadiene rubber one by one to obtain a small fraction of butadiene repeating units of only 1 New structure of the child.