摘要
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。
The anionic polymerization of methyl methacrylate（MMA） initiated by n-butyl lithium（n-BuLi） was conducted in tetrahydrofuran （THF） solvent,in which potassium t-butoxide （t-BuOK） and potassium phenolate （POK） were added as the side reaction inhibitors.The molecular weight,molecular weight distribution （MWD） and molecular structure of the polymers were characterized by Gel Permeation Chromatography （GPC） and proton Nuclear Magnetic Resonance （^1H-NMR）.Results revealed that the lithium counterion （Li^＋） in the active species was replaced by K^＋ via the ion exchange reaction between t-BuOK and n-BuLi.By means of the substitution reaction,the side reactions of MMA could be inhibited to some extent.When the molar ratio of t-BuOK to n-BuLi was greater than 10,the controllable anionic polymerization of MMA could be realized at 0℃.The MWD of PMMA was as narrow as 1.22 and the number-average molecular weight （Mn） was consistent with the theoretical value well.This means the side reaction in the anionic polymerization of MMA was suppressed well.Furthermore,POK could associate with K^＋ in the active species in the system,which further promoted the inhibition effect on the side reactions.As a result,the controllable anionic polymerization of MMA could be realized at higher temperature （40℃）,the MWD of the synthesized PMMA was narrow （1.24） and Mn was approximate to the theoretical value.
出处
《功能高分子学报》
CAS
CSCD
北大核心
2016年第3期258-266,共9页
Journal of Functional Polymers
基金
国家自然科学基金(51373052)
关键词
醇钾
酚钾
阴离子聚合
甲基丙烯酸甲酯
potassium alkoxide
potassium phenoxide
anionic polymerization
MMA
