星状羟基功能化聚苯乙烯/聚乙烯两嵌段共聚物的合成

Synthesis of the star-liked hydroxyl functionalized block copolymer aPS-b-PE catalyzed by CpTiCl_3/Zn/I_4/MAO

采用CpTiCl3/I4/Zn催化体系引发苯乙烯活性自由基聚合,之后引入乙烯,以MAO为助催化剂催化乙烯配位聚合,合成无规聚苯乙烯-聚乙烯嵌段共聚物aPS-b-PE。考察了聚合温度、时间、乙烯压力和Al/Ti摩尔比等反应条件对共聚合的影响。使用氯仿对共聚物进行抽提,采用GPC、DSC和13C NMR对氯仿可溶部分的结构和性能进行了表征。DSC结果显示,共聚物的玻璃化转变温度Tg为86℃,属于无规聚苯乙烯相玻璃化转变温度,熔点Tm为112℃,属于聚乙烯相的熔点。13C NMR结果证明聚苯乙烯链段为无定形态。这些表征结果表明星状羟基功能化aPS-b-PE共聚物是嵌段结构。

By one-pot technique, the copolymerization of styrene with ethylene promoted by CpTiCI3/I4/Zn catalytic system to produce the star-like hydroxyl functionalized S-E block copolymers was investigated via sequential monomer addition strategy in the present of methylaluminoxane（MAO） as cocatalyst for the coordination polymerization stage. The effect of temperature, time, ethylene pressure and the ratio of A1/Ti in mol on the polymerization performance was discussed. Independently from the feed composition, basic S-E block copolymer was obtained, together with aPS, from which the former was separated by solvent extraction. The CHC13-soluble product was determined by GPC, DSC, and 13C NMR. The DSC result showed that the copolymer featured a glass transition temperature （Tg= 84 ℃） which attributed to the Tg ofaPS domain and melting temperature （Tm=ll2 ℃） which attributed to the Tm of PE domain. The block structure of the aPS-b-PE copolymer was further confirmed by 13C NMR, these results indicated that the PS segment was amorphous and the PE one was crystalline.