活性正离子聚合制备聚(异丁烯-b-α-甲基苯乙烯)嵌段共聚物  

SYNTHESIS OF POLY(ISOBUTYLENE-b-α-METHYLSTYRENE) COPOLYMERS BY LIVING CATIONIC POLYMERIZATION

作　　者：伍一波[1] 郭文莉[2] 李树新[2] 龚惠勤[1] 

机构地区：[1]北京化工大学材料科学与工程学院,北京100029 [2]北京石油化工学院材料科学与工程系,北京102617

出　　处：《高分子学报》2008年第6期574-580,共7页Acta Polymerica Sinica

基　　金：北京市高等学校人才强教计划资助项目(弹性体与生物医用弹性材料)

摘　　要：以2-氯-2,4,4-三甲基戊烷(TMPCl)/TiCl4/质子捕捉剂(DtBP)为引发剂体系,引发异丁烯聚合,随后加入1,1-二(4-甲基苯基)乙烯作为封端剂稳定末端碳正离子,再引入四异丙醇钛(Ti(OiPr)4),降低Lewis酸性,继续引发α-甲基苯乙烯聚合,实现活性正离子聚合制备聚(异丁烯-b-α-甲基苯乙烯)嵌段共聚物.考察了α-甲基苯乙烯聚合时间对单体转化率、产物的dn/dc值、分子量及其分布的影响以及四异丙醇钛对聚合速率的影响.并通过体积排斥色谱法/紫外检测器/示差折光指数/多角激光光散射、1H-NMR以及DSC以对产物进行表征.实验结果表明,嵌段共聚物分子量分布窄(MWD≤1.2),单体转化率与分子量呈线性关系,聚合速率对单体浓度呈一级动力学关系,具有活性聚合的特征.Ti(OiPr)4能有效稳定活性中心,降低聚合速率.聚(异丁烯-b-α-甲基苯乙烯)嵌段共聚物的DSC测试发现明显的两个Tg,表明存在微相分离结构.The efficient synthesis of poly（isobutylene-b-α-methylstyrene） （PIB-b-PαMeSt） copolymer has been accomplished by living cationic polymerization using sequential monomer additions.Living PIB was first prepared by the 2-chloro-2,4,4-trimethylpentane （TMPCl）/TiCl4/DtBP/C6H 12 ∶MeCl=50∶50 V/V/-80℃ polymerization system.Subsequently,the living PIB chain end was converted to the corresponding diphenylalkyl end by capping with 1,1-di-p-tolylethylene （DTE）.Ti（OiPr）4 was added to reduce the Lewis acidity,followed by the addition of αMeSt.When Ti（OiPr）4 was introduced into the polymerization system,the complexes of Ti2Cl 8-x （OiPr）x were formed rapidly.By changing the stoichiometry,the Lewis acidity of TiCl4 can be moderated in a wide range.This was corroborated by our visual observation that upon addition of Ti（OiPr）4 the orange color of the diphenyl carbenium ion turned into the yellow-green color.This indicated that highly reactive species convert into less reactive species.The PIB-b-PαMeSt copolymers were characterized by ^1H-NMR spectroscopy and triple detection SEC： refractive index （RI）,multi-angle laser light scattering （MALLS） and ultraviolet （UV） detector.The effects of the polymerization time for αMeSt （t2） on conversion of monomer,dn/dc value,molecular weight and molecular weight distribution as well as the effect of Ti（OiPr）4 concentrations on the polymerization rate were investigated.The results showed that the dn/dc values of block copolymers increased with increasing polyαMeSt compositions.And molecular weight distributions of the resulting polymers stayed relatively narrow,less than 1.2 （MWD≤1.2）.LS,RI and UV traces of the resulting PIB-b-PαMeSt copolymer had the same eluting time without any tailing which demonstrated the blocking efficiency is close to 100%.The kinetics of the cationic polymerization of αMeSt in the presence of Ti（OiPr）4 were determined by the gravimetric monitoring of the polymer yield as a function of the rea

关 键 词：活性正离子聚合 聚(异丁烯-b-α-甲基苯乙烯) 多角激光光散射 动力学 

分 类 号：O631.3[理学—高分子化学]