稀土催化剂催化乙烯/共轭双烯烃高顺式共聚合制备新型高性能橡胶

Introduction of ethylene unit into cis-1,4 conjugated diene via copolymerization of ethylene and conjugated dienes can lead to novel high-value rubber materials with reducing C=C unsaturated bond content on the polymer chain, thus improving its resistance towards aging, chemical agents, oil and abrasion. Hence, cis-1,4 conjugated dienes and ethylene copolymers hold a wide potential applications in tire manufacture. Because of huge differences in the reactivities of two monomers and polymerization mechanisms, cis-1,4 selective copolymerizations of ethylene and dienes are highly challenging projects to date. Herein in this project, half-sandwich rare-earth metal complexes will be designed and synthesized by tuning Lewis acid of the metal center and ligand steric effect to achieve copolymerizations of ethylene with conjugated dienes through decreasing the energy barriers of coordination and insertion between two monomers. The influences of catalyst structure on the polymerization activity, cis-1,4 regioselectivity, and reaction ratios of two monomers are investigated in detail. The influences of reaction conditions including temperature, monomer concentration, ethylene pressure, and solvent type on the incorporation of ethylene and sequence distribution of copolymer are also studied. Based on the above results, random and multi-block copolymers of ethylene and cis-1,4 diene with high ethylene content, high molecular weight are prepared on the optimal conditions, which can be applied as novel high performance rubbers. Furthermore, the relationship between catalyst structure and polymerization behavior is elucidated by means of DFT calculation, which prodives a theory evidence to developing novel catalyst systems for effciency copolymerizations of ethylene with conjugated dienes.

利用来源丰富和廉价的乙烯与共轭双烯烃顺1,4-选择性共聚合，得到的共聚物主链不饱和双键含量低，具有耐老化、耐臭氧、耐油、耐磨和高强度等优异的物理机械性能，是高附加值的新型橡胶材料，有巨大的潜在应用价值。然而两种单体活性差异大、聚合机理不同，乙烯和共轭双烯烃高选择性可控共聚，是具有挑战性的课题。本项目拟设计新型杂环稠合单茂稀土配合物，通过调节中心金属的Lewis酸性和空间效应，缩小单体间配位与插入活化能的差异，实现乙烯与共轭双烯烃共聚。探索催化剂结构对聚合活性、双烯烃顺1,4-选择性与单体间竞聚率的影响。研究聚合反应条件如温度、单体浓度、乙烯压力、溶剂类型等对乙烯插入率和序列长度及分布的控制作用，最终获得高乙烯含量、顺1,4-结构、高分子量、多嵌段和无规序列分布的乙烯/共轭双烯烃新型高性能橡胶。借助DFT理论计算揭示催化剂与聚合行为之间的构效关系，为催化体系的开发提供理论指导。

利用来源丰富和廉价的乙烯与共轭双烯烃选择性共聚合，得到的共聚物主链不饱和双键含量低，具有耐老化、耐臭氧、耐磨和高强度等优异的物理机械性能，是高附加值的新型橡胶材料，有巨大的潜在应用价值。.本项目设计合成了带侧壁的单茂稀土配合物和噻吩稠和的单茂稀土配合物，利用这类催化剂研究了它们在助催化剂存在下催化乙烯与2,3-二甲基丁二烯（DMBD）共聚合、乙烯与共轭二烯及环烯烃三元共聚合、乙烯与氟代苯乙烯的共聚合反应。通过乙烯与DMBD共聚合得到2,3-二甲基丁二烯单元为1,2-选择性并具有良好的拉伸强度和高断裂伸长率的新型橡胶材料；通过乙烯与共轭二烯及环烯烃三元共聚合得到分子量高、乙烯与环烯烃插入率可调、丁二烯单元顺-1,4结构含量可高达（cis-1,4: > 90 mol%）、玻璃化转变温度低（-93 ℃～-101 ℃）、拉伸强度5.03 MPa、断裂伸长率610 %的新型橡胶材料；通过乙烯与氟代苯乙烯共聚合得到具有一个来自E-SF无规共聚链段的玻璃化转变温度（Tg = -22.2 ℃ ～ 5.1 ℃）和一个来自结晶性连续E-E链段的熔点（Tm = 42.3 ℃ ～ 130.2 ℃）的共聚物。E-SF共聚物在室温下表现出良好热塑性弹性体（TPE）的性质，其拉伸强度最高为39.5 MPa，断裂伸长率为774 %。系统地研究了催化剂结构对聚合活性、共轭二烯与氟代苯乙烯选择性与单体间竞聚率的影响；聚合反应条件如单体浓度、乙烯压力等对乙烯插入率和序列长度及分布的控制作用;共聚物微观结构对力学性能的影响。利用DFT理论计算揭示了共聚机理。.另外，我们系统研究了乙烯-1,3-丁二烯共聚物微观结构如乙烯含量、分子量及分布、丁二烯顺-1,4含量、序列分布（梯度或无规等）对生胶和硫化胶力学性能的影响，并与顺丁橡胶对比，研究这种新型橡胶的特点和优势，为其应用提供基础数据。