链穿梭共聚制备新型多嵌段烯烃共聚物

Recently, the chain shuttling copolymerization (CSC) of two different monomers by two Group 4 metal catalysts those show different co-monomer selectivity has emerged as a powerful technology for the preparation of olefin block copolymers with different segments. This project focuses on design and synthesis a series of novel multi-block copolymers those containing alternating “hard-soft” sequences via the highly efficient CSC, on the basis of a battery of catalyst/co-catalyst/(co-)monomer/chain transfer agent screening. The “hard” sequences could be the linear polyethylene (PE), isotactic polypropylene (iPP) or syndiotactic polystyrene (sPS), while the “soft” sequences could be the amorphous PE, PP, PS, or their random copolymers with cyclic olefin or some functional co-monomers. These novel multi-block copolymers are expected to have much improved physical performance such as impact and flexibility resistance, tensile strength, flexibility, transparency, or optical properties. The relationship between reaction conditions (catalyst/(co-)monomer/chain transfer agent ratio), micro-structure (molecular weight and distribution, sequence composition and distribution) and physical properties (melting point, glass transition temperature, modulus, elongation, etc.) of the resulting multi-block copolymers will be well studied. Finally, the expected high performance thermoplastic elastomer, cyclic olefin copolymer or amphiphilic functional multi-block copolymers with tailored structure and properties can be easily obtained via the successful CSC.

近些年发展起来的链穿梭共聚在高分子拓扑结构设计、分子量调控、聚合效率等多方面体现出传统聚合方法难以比拟的优势。本项目拟通过选择与优化一系列高选择性催化剂/助催化剂以及与之匹配的链转移剂，利用高效率链穿梭共聚方法合成以结晶性iPP、线性PE、sPS等为硬段、无定形烯烃均聚物或烯烃与环烯烃、功能化共聚单体无规共聚物为软段，具有软硬交替结构的新型多嵌段共聚物。在分析研究与优化典型选择性催化体系可逆链转移聚合反应的基础上，首先确定与之匹配的链转移剂，并进一步研究不同选择性的催化体系之间的链穿梭共聚，优化聚合反应条件，实现具有新型拓扑结构的综合性能优异的新型多嵌段烯烃共聚物材料的高效合成。通过调节链穿梭聚合反应条件来调控多嵌段共聚物的分子量、软硬段组成和比例等，揭示多嵌段共聚物结构与性能之间的关系，根据需求实现对新型多嵌段共聚物结构的设计和剪裁。

链穿梭共聚具有很多传统聚合方法无可比拟的优势，如催化剂利用效率高，易于制备多嵌段共聚物，适应于工业生产与应用等，从而引起了人们极大的研究兴趣。本项目通过选择与优化一系列高选择性催化剂与合适的链转移剂进行搭配，合成具有新型链段结构包括以结晶性的聚乙烯、全同聚丙烯为硬段、无规聚烯烃或烯烃与环烯烃等无规共聚物为软段的多嵌段共聚物。利用核磁、GPC、DSC等分析手段证实，向优选的选择性催化剂体系中添加适当的链穿梭剂可以有效的实现具有不同结构特征的分子链段的组合，形成新型的多嵌段共聚物。新型多嵌段共聚物的拉伸力学性能或透明性等较单纯的物理共混物或相应的单一结构聚合物有了显著的提高。