开环易位聚合-加氢法制备侧链功能化聚烯烃

以1,5-环辛二烯为起始原料,通过一系列反应制备了功能性单体5-溴代丙酸酯基-环辛烯(M1)。采用Grubbs II代催化剂(G2)对单体M1进行开环易位聚合反应(ROMP)制备了均聚物P1。调整M1与环辛烯的单体投料比,通过开环易位共聚反应制备了一系列无规共聚物P5%、P10%、P15%和P20%;共聚物中功能性单体M1的含量与单体配比接近,且无规共聚物的相对分子质量分布比均聚物要窄。对不饱和聚合物进行化学加氢反应,制备了饱和的功能化聚烯烃。热分析结果表明,随着功能单体M1投料比例的增加,无规共聚物的熔点呈现下降趋势;加氢后的饱和聚合物HP1的玻璃化转变温度比不饱和聚合物P1提高了40℃;加氢后饱和聚合物的热稳定性提高。

Preparation of Side-Chain-Functionalized Polyolefins via Ring-Opening Metathesis Polymerization and Hydrogenation

Taking 1,5-cyclooctadiene as starting material,the functional monomer(cyclooct-4-en-1-yl-2-bromopropanoate,M1)was prepared through a series of chemical reactions,including the selective epoxidation reaction of 1,5-cyclooctadiene,the reduction reaction of cyclooctadiene monoepoxide and the esterification reaction between cyclooct-4-enol and 2-bromopropiomyl bromide.The ring-opening metathesis polymerization of M1 with Grubbs 2nd generation catalyst(G2)produced homopolymers(P1).The molecular weight of resulted polymers increases gradually and the molecular weight distribution becomes broader as the increase in the monomer concentration.In addition,a series of random copolymers of M1 and cyclooctene(P5%,P10%,P15%and P20%)were also prepared by adjusting the feeding ratio of M1(5%,10%,15%and 20%).The structure of resulting(co)polymers was characterized by FT-IR,1 H and 13C-NMR spectra.The results indicate that the incorporation contents of M1in the random copolymers are close to the theoretical value in the feeding and the molecular weight distributions of copolymers are narrower than those of homopolymers.The DSC analysis shows that the melting points of copolymers decrease gradually as the increase in the contents of functional monomer in the copolymers,which can be ascribed to the increase in the numbers of side chains in the random copolymers.The chemical hydrogenation of unsaturated polymers by using p-toluenesulfonyl hydrazide/tri-n-propylamine yielded the corresponding saturated polymers,which could be considered as side-chain-functionalized polyolefins.In other words,the hydrogenated polymers(HP1)are the equivalents of ethylene/bromo propionic acid vinyl ester copolymers with 25% of functional monomer.From DSC curves,the saturated polymers(HP1)have a much high glass transition temperature than the corresponding unsaturated polymers(P1).The TGA results show that the saturated HP1 has better thermal stability than the unsaturated P1.