叔丁基锂引发合成聚苯乙烯-异戊二烯-苯乙烯三嵌段共聚物

摘要

Poly(styrene-isoprene-styrene) triblock copolymer (SIS) with narrow molecular weight distribution was prepared by anionic polymerization,using t-BuLi as initiator and cyclohexane as solvent.The influences of the amount of t-BuLi,polymerizing temperature and polymerizing time on the molecular weight (Mn) and molecular weight distribution (Mw/Mn) of SIS were studied to optimize the reaction conditions.The samples were characterized by nuclear magnetic resonance spectrscopy (NMR) and Fourier transform infrared spectrscopy (FT-IR).The molecular weight and molecular weight distribution of the samples were measured accurately by size exclusion chromatography-multi angle laser light scattering (SEC-MALLS).The micro-phase separation structures of the triblock copolymers were investigated by differential scanning calorimetry (DSC).It was found that the triblock copolymer has the micro-phase separation structure and three glass transition temperatures,demonstrating that there are styrene block phase,conjugated isoprene block phase,and styrene/conjugated isoprene copolymer block phase in SIS.%以叔丁基锂为引发剂,环己烷为溶剂,通过阴离子反应制备了窄分子量分布的聚苯乙烯-异戊二烯-苯乙烯三嵌段共聚物(SIS).研究了叔丁基锂用量、反应时间及反应温度对SIS分子量(Mn)及分子量分布(Mw/Mn)的影响,得到了较优化的聚合工艺条件.采用核磁共振波谱(NMR)、傅里叶变换红外光谱(FT-IR)等方法对嵌段聚合物进行了表征和分析,并采用凝胶渗透色谱-多角度激光散射技术(SEC-MALLS)对其分子量及分子量分布进行了精确测定.利用差示扫描量热仪(DSC)研究了三嵌段共聚物的微观相分离结构,发现该三嵌段共聚物具有微观相分离结构,存在3个玻璃化转变温度,即苯乙烯嵌段相、异戊二烯嵌段相及苯乙烯/异戊二烯互溶过渡相.