Synthesis of isotactic polypropylene containing a terminal Cl, OH, or NH2 group via metallocene-mediated polymerization/chain transfer reaction
Synthesis of isotactic polypropylene containing a terminal Cl, OH, or NH2 group via metallocene-mediated polymerization/chain transfer reaction
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DOI：
10.1021/ma0211582
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发表时间：
2002-12-03
期刊：
影响因子：
5.5
通讯作者：
Chung, TC
中科院分区：
文献类型：
--
作者：
Dong, JY;Wang, ZM;Chung, TC
本文讨论了一种直接（一锅）聚合法制备末端含有Cl、OH和NH 2官能团的等规聚丙烯（i-PP）。该化学涉及在苯乙烯衍生物（St-f）存在下使用rac-Me 2Si [2-Me-4-Ph（Ind）]（2）ZrCl 2/MAO络合物进行丙烯介导的聚合，所述苯乙烯衍生物（St-f）携带Cl（St-Cl）或硅烷保护的OH（St-OSi）或硅烷保护的NH 2（St-NSi 2），然后氢化。显然，丙烯增长链端参与了一种轻松的连续链转移。反应，先与St-f反应，然后与氢气反应，在适当的St-f和氢气浓度下具有高的催化剂反应性。聚合物分子量与[St-f]/[丙烯]的摩尔比成反比，链转移常数（k（tr）/k（p））分别为St-Cl的1/21、St-NSi 2的1/34和St-OSi的1/48。在样品后处理步骤期间，在酸性水溶液中水解两种硅烷保护基团，以获得具有末端OH和NHz基团的所需i-PP聚合物（即，PP-t-St-OH和PP-t-St-NH2）。通过端基分析和扩链反应确定了末端官能团。尽管具有高分子量，但PP中的末端官能团在溶液和熔体中与聚己内酯（PCL）进行偶联反应以形成PP-b-PCL二嵌段共聚物，其是PP/ PCL聚合物共混物中非常有效的增容剂。
This paper discusses a direct (one-pot) polymerization process to prepare isotactic polypropylene (i-PP) having a terminal functional group including Cl, OH, and NH2. The chemistry involves metallocene-mediated propylene polymerization using rac-Me2Si[2-Me-4-Ph(Ind)](2)ZrCl2/MAO complex in the presence of styrene derivatives (St-f), carrying a Cl (St-Cl) or a silane-protected OH (St-OSi) or a silane-protected NH2 (St-NSi2), followed by hydrogenation. Apparently, the propylene propagating chain end engages in a facile consecutive chain transfer. reaction, reacting with St-f and then hydrogen, with high catalyst reactivity under the proper St-f and hydrogen concentrations. The polymer molecular weight was inversely proportional to the molar ratio of [St-f]/[propylene] with a chain transfer constant (k(tr)/k(p)) of 1/21 for St-Cl, 1/34 for St-NSi2, and 1/48 for St-OSi, respectively. Both silane protecting groups were hydrolyzed in acidic aqueous solution during the sample workup step to obtain the desirable i-PP polymers with a terminal OH and NHz group (i.e., PP-t-St-OH and PP-t-St-NH2). The terminal functional group was confirmed by end group analysis and chain extension reaction. Despite the high molecular weight, the terminal functional group in PP engages a coupling reaction with polycapolactone (PCL) in solution and melt to form PP-b-PCL diblock copolymers that are very effective compatibilizers in PP/ PCL polymer blends.