论文部分内容阅读
采用7Li-NMR对正丁基锂(n-BuLi)与不同摩尔比叔丁醇钾(t-BuOK)的混合物在四氢呋喃与环己烷溶液中的体系进行了分析.继而以1,1-二苯基己基锂作为引发剂,分别采用苯酚锂、叔丁醇钠以及t-BuOK作为副反应抑制剂,进行了甲基丙烯酸正丁酯(BMA)和甲基丙烯酸甲酯(MMA)的负离子嵌段共聚合,并用GPC、1H-NMR对聚合物的结构进行了表征.结果发现n-BuLi与t-BuOK会产生Li与K交换的反应,形成不具备引发活性的t-BuOLi,以及以K为反离子的活性种.其对MMA类极性单体嵌段聚合的副反应有着极为有效的抑制作用.过量的t-BuOK,将进一步提高对副反应的抑制作用.在体系中nt-BuOK/nn-BuL≥20后,即便聚合温度升高至40℃,BMA与MMA极性单体嵌段聚合的总产率也可达到100%,且分子量分布仅为1.40,呈单峰分布.实测的Mn与设定的Mn非常接近;采用1H-NMR实测的nMMA/nBMA也与原料十分接近.从而为MMA类极性单体嵌段聚合的工业化奠定了基础.
7Li-NMR analysis of the system of a mixture of n-BuLi and different molar ratios of potassium t-butoxide (t-BuOK) in tetrahydrofuran and cyclohexane followed by 1,1-bis Phenyl-hexyl lithium was used as initiator, respectively, and the negative ions of n-butylmethacrylate (BMA) and methylmethacrylate (MMA) were intercalated with lithium phenoxide, sodium tert-butoxide and t- And the structure of the polymer was characterized by GPC and 1H-NMR. It was found that the reaction of Li-K with n-BuLi and t-BuOK resulted in the formation of t-BuOLi with no initiating activity, Which is an active species of the counter ion and has an extremely effective inhibiting effect on the side reaction of the MMA type polar monomer block polymerization. The excessive t-BuOK further increases the side effect inhibition. In the system nt-BuOK / nn-BuL≥20, the total yield of block polymerization of BMA and MMA polar monomer can reach 100% even though the polymerization temperature is increased to 40 ℃, and the molecular weight distribution is only 1.40, showing a unimodal distribution. Of Mn is very close to the set Mn; nMMA / nBMA measured by1H-NMR is also very close to the raw material, so as MMA polar monomer block polymerization It laid the foundation for industrialization.