稀土催化剂通过配位共聚合方法制备高立构规整性1,3-环己二烯基共聚物

1,3-cyclohexadiene (CHD), one kind of cyclic conjugated diene showing both conjugated diene and cyclic olefin quality, has received considerable attention from academia and industry. It exhibits different regio- and stereospecificity in coordinative-insertive polymerization, affording various regio- and stereoregular poly(1,3-cyclohexadiene)s (PCHDs). Especially, these regular PCHDs are unique in the polydiene family due to their excellent thermal property (Tm: 200-300 C) attributed to the cyclic nature of the repeat unit of cyclohexane. Moreover, the presence of a residual double bond renders PCHDs as ideal precursors for the synthesis of a broad range of high-performance functionalized polymers through chemical modification. However, these regular PCHDs are not melt processable due to their insolubility in organic solvents or their melting temperatures higher than temperature of thermal degradation. For improvement of their processability, the incorporation of a olefin comonomer is expected to be a useful method. Unfortunately, previous reports demonstrated that the coordinative-insertive copolymerizations of CHD by organometallic catalysts were rather difficult. Until now, only few titanium and scandium catalysts could successful promote the coordinative-insertive copolymerizations of CHD with ethylene or styrene recently. However, the highly regio- and stereoselective copolymerization and block copolymerization of CHD with olefins have remained a challenge to date. .Recently, we have demonstrated that the half-metallocene scandium alkyl catalysts showed high regio- and stereocontrol in the copolymerization of CHD with ethylene or styrene, yielding cis-1,4-CHD based copolymer. In this project, we will pay our attention to synthesize a series of novel rare earth metal catalysts bearing strongly electron-donating ligands with large steric hindrance such as substituted fluorene or fluorene and cyclopentadiene analogs. Using these catalysts, we wish that the coordinative-insertive copolymerization and terpolymerization of CHD with olefins such as ethylene, styrene, alpha-olefin, conjugated diene might be successful achieved to produce various regio- and stereoregular CHD-based copolymers. We also hope to promote the controlled copolymerization of CHD with olefins by the living rare earth metal catalyst or the two rare earth metal catalysts belonging chain-shuttling nature, forming the unprecedented block copolymers containing the regio- and stereoregular PCHD segment. Various chemical modification reactions such as hydrogenation, dehydrogenation, halogenation, oxidation, etc. will be occurred to these regular CHD-based copolymers for the synthesis of a broad range of functionalized polymers. DFT calculation will be utilized to demonstrate the mechanism of the coordinative-insertive copolymerization of CHD, which directs us to design new rare earth metal catalysts and new polyolefin materials.

1,3-环己二烯（CHD）结构中兼有共轭二烯烃和环烯烃的特点，它在聚合反应中表现出来的多反应位点、立构选择性和其聚合物独特的耐热性、刚性及可化学修饰性引起了人们的关注。然而,目前利用金属催化剂通过配位聚合方法制备高立构规整性1,3-环己二烯基共聚物还很少见。本项目在前期工作的基础上，拟合成一系列以取代芴、类芴、类茂为辅助配体的新稀土金属催化剂，实现高选择性地促进CHD和乙烯、苯乙烯、alpha-烯烃、共轭二烯烃的配位共聚合和三聚合反应，制备高立构规整性1,3-环己二烯基共聚物；寻找具有活性聚合性质的稀土催化剂或者具有链穿梭性质的两种相匹配稀土催化体系，合成含有高立构规整性聚1,3-环己二烯片段的嵌段共聚物；发展所得1,3-环己二烯基共聚物化学改性的新方法，得到高性能的功能化聚烯烃材料；利用DFT理论计算阐明CHD参与的配位共聚合反应机理，为新稀土催化剂和聚烯烃材料的设计和合成提供理论依据。

稀土金属催化剂是近年来烯烃配位聚合领域的研究热点。申请人长期聚焦烯烃配位聚合反应和聚烯烃工业这一领域，立足稀土金属有机催化剂研究，在阳离子稀土金属催化剂的设计合成、高立构选择性或组成和序列分布可控的烯烃配位（共）聚合反应的开发、结构和性能可控的聚烯烃高分子的制备以及配位聚合反应机理的研究等方面取得了一系列原创性成果。在本项目的执行期间，我们通过对支撑配体、中心金属和对称性构型等方面的调控，合成了多种具有特定电子效应、空间位阻和对称性的非茂和单茂稀土金属催化剂，实现了对1,3-环己二烯和其它一些烯烃单体聚合反应中活性、立体选择性、分子量以及共聚物插入率和序列分布的控制，制备了一些具有广泛工业应用前景或者难以用以往催化剂制备的聚烯烃高分子新材料。例如实现了1,3-环己二烯1,4-选择性聚合反应、1,3-环己二烯和苯乙烯或异戊二烯类嵌段共聚合反应、1,3-环己二烯、苯乙烯和异戊二烯三聚合反应（1,3-环己二烯1,4-选择性高达100%）；实现了异戊二烯、月桂烯和罗勒烯等共轭二烯烃单体的高顺式1,4-聚合反应（顺式1,4-选择性高达100%）；实现了苯乙烯的高间规均聚合以及和乙烯的类嵌段共聚合反应（间规选择性高达100%）。我们还在DFT理论计算的基础上，阐明一些烯烃的配位聚合反应机理，为新稀土金属催化剂的设计提供了理论依据。本项目的研究成果推动了金属烯烃配位聚合催化剂的研究进展，为我国聚烯烃工业的发展提供了金属催化剂的技术储备，为我国的稀土资源的利用提供了技术支撑。.在本项目的执行期间，我们在Macromolecules (3篇)，Polym. Chem. (3篇)，Macro. Rapid Commun. (1篇)，Organometallics (2篇)等国际学术期刊上发表SCI论文17篇；全部已发表的论文近五年SCI他引710次，单篇最高他引67次；申请国家发明专利15项，授权4项；参加了国内外学术会议专题报告8次；组建稀土金属有机和高分子合成科研团队，已培养了16名青年稀土金属有机和高分子合成科研人员。2014年入选国家自然科学基金委优秀青年基金项目和教育部新世纪优秀人才支持计划。