摘要
鉴于聚合物的立构规整度对其性能起着重要的作用,如何提高聚合物的立构规整度一直以来都是配位聚合领域的重要研究课题。经过几十年的发展,配位聚合已经在α-烯烃、苯乙烯、共轭二烯烃等非极性烯烃单体的立构选择性聚合方面取得了巨大的成就。但非极性聚烯烃材料表面性能差,而化学性质稳定,难以被后功能化。因此通过极性单体的立构选择性聚合将极性基团引入聚烯烃大分子链中对于提高其性能具有非常重要的意义。然而,在传统的配位聚合中,单体上的极性原子(基团)易于向金属中心配位,导致催化体系失去立构选择性,甚至失去活性。因此选择合适的配体、金属种类与极性单体组合的策略对实现立构选择性聚合至关重要。近年来,针对2-乙烯基吡啶、含杂原子苯乙烯衍生物以及硼氮杂芳香型乙烯基单体的定向聚合,开发了大量的稀土金属配合物催化体系,聚合物的立构规整度取得了较大的突破,同时对单体上极性原子在聚合中的作用也有了新的认识。本综述以单体种类为主线,详细讨论了配体的结构、取代基的电子效应、空间位阻效应、中心稀土金属种类和聚合溶剂等对催化剂聚合活性、立构选择性的影响,并探讨可能的聚合反应机理。
It has been a long-standing research topic in the field of coordination polymerization to improve the stereoregularity of polymers because the stereoregularity has an important influence on the physical and mechanical properties.Over the past few decades,coordination polymerization has gained great achievement in the field of stereospecific polymerization of nonpolar monomers,such asα-olefins,styrene and conjugated dienes.However,the polyolefins suffer from poor surface properties and compatibility and are difficult to be post-functionalized due to their nonpolar nature and stable chemical properties.Therefore,it is of greatsignificance to introduce polar group into the nonpolar polyolefins via stereoselective polymerization of polar monomers.In traditional coordination polymerization,the polar atom/group on the monomer is readily coordinated to the Lewis-acidic active metal center,consequently the catalyst systems lose stereo-control or even activity.Therefore,the combination of properly chosen ancillary ligand,metal center and polar monomers is of great significance for stereo-controlled polymerization of vinyl monomers.In recent years,a variety of rare-earth metal complexes have been exploited for the stereospecific polymerization of aromatic polar vinyl monomers,e.g.2-vinyl pyridine,hetero-atom functionalized styrene and boraza(BN)aromatic vinyl monomer,and great breakthrough has been achieved on the stereoregularity control.These interesting results enrich the understanding of the polar atom/group in the coordination polymerization.Herein,the review focuses on the species of the aromatic polar monomers,summarizes the influence of the backbone structure,electronic effect,steric hindrance of the ancillary ligands,rare-earth metal,and solvent effect on polymerization activity and stereo-selectivity,and discusses the proper related polymerization mechanism.
作者
牟泽怀
王银军
谢鸿雁
Zehuai Mou;Yinjun Wang;Hongyan Xie(School of Materials Science and Chemical Engineering,Ningbo University,Ningbo 315211,China;China-Australia Institute for Advanced Materials and Manufacturing,Jiaxing University,Jiaxing 314000,China)
出处
《化学进展》
SCIE
CAS
CSCD
北大核心
2020年第12期1885-1894,共10页
Progress in Chemistry
基金
国家自然科学基金项目(No.21805143,21801097)
宁波市自然科学基金项目(No.2018A610118)
宁波大学王宽诚幸福基金资助。
