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以正丁基锂(n-BuLi)为引发剂,叔丁醇钾(t-BuOK)和苯酚钾(POK)为副反应抑制剂,实现了甲基丙烯酸甲酯(MMA)在四氢呋喃(THF)溶剂中的阴离子聚合。采用凝胶渗透色谱(GPC)、核磁共振氢谱(1 H-NMR)等研究了产物的数均分子量、分子量分布(MWD)和分子结构。结果表明:t-BuOK与n-BuLi之间发生反离子交换反应使活性中心的反离子Li~+被K~+替换,从而在一定程度上抑制了MMA聚合过程中的副反应,当n(t-BuOK)/n(n-BuLi)≥10时,可在0℃下实现MMA的可控阴离子聚合;PMMA分子量分布较窄(1.22),且数均分子量与设计值十分接近,MMA聚合的副反应得到了有效控制;进一步添加的POK能与活性中心的K~+配合,促进对MMA聚合副反应的抑制,使MMA的可控阴离子聚合能在较高温度(40℃)下得以实现,所合成的聚甲基丙烯酸甲酯(PMMA)数均分子量分布窄(1.24)且数均分子量符合设计值。
(N-BuLi) as initiator, t-BuOK and POK as side reaction inhibitors, the effect of methyl methacrylate (MMA) in tetrahydrofuran (THF) Anionic polymerization in solvents. The number average molecular weight, molecular weight distribution (MWD) and molecular structure of the product were investigated by gel permeation chromatography (GPC) and 1 H-NMR. The results showed that the counter ion exchange reaction between t-BuOK and n-BuLi led to the replacement of the counter ion Li ~ + in the active center by K ~ +, which inhibited the side reaction in the polymerization of MMA to a certain degree. When n t-BuOK) / n (n-BuLi) ≥10, the controlled anionic polymerization of MMA can be achieved at 0 ℃. The molecular weight distribution of PMMA is narrow (1.22), and the number average molecular weight is close to the designed value. Side reaction was effectively controlled. Further addition of POK could cooperate with K + in the active site to promote the inhibition of the side reaction of MMA polymerization, so that the controlled anionic polymerization of MMA could be realized at a higher temperature (40 ° C) The synthesized poly (methyl methacrylate) (PMMA) had a narrow number average molecular weight distribution (1.24) and the number average molecular weight was within the designed value.