α-甲基苯乙烯低聚物的合成

PREPARATION AND CHARACTERIZATION OFα-METHYLSTYRENE OLIGOMER

采用酸化的膨润土为催化剂,以α-甲基苯乙烯为原料合成了重均相对分子质量为3 891,相对分子质量分布(?)/(?)=2．42的聚α-甲基苯乙烯。考察了反应温度、反应时间、催化剂用量、原料纯度对产物分子量及分布的影响。当催化剂用量为原料质量的2．0%,反应温度为—3℃,反应时间为40 min时,原料转化率为60%,产物软化点为150℃。产物相对分子质量分布经GPC测定。~1H与^(13)C NMR谱分析表明本品应是以烯封端的聚α-甲基苯乙烯。反应过程无废酸,利于环保。

α-methylstyrene oligomer [P（α-MS）] with Mw=3 891 and Mw/Mn=2.42 with the softening point of 150 ~C was prepared from α-methylstyrene by the catalysis of acidified bentonite. The influences of reaction temperature and time and the quantity of the catalyst on the molecular weight and its distribution in the product were investigated and the optimal conditions were found as follows： -3 ℃, catalyst 2 % of a methylstyrene, reaction time 40 min. Under these conditions, the conversion of α-methylstyrene was 60%. The molecular weight and distribution of P（α-MS） was determined based on GPC. Results of ^1H and ^13C NMR confirmed that there is active --C=C- terminal unit in Pa-MS. This process produces no waste acid, and is environmentally friendly.