生物质萜烯基热塑性弹性体的设计与制备研究

Human beings are becoming increasingly aware of the fact that fossil raw materials such as oil and coal are finite resources and would eventually dry up. Bio-based raw materials are the only renewable alternatives to replace fossil carbon source. Terpenes are a large and diverse class of organic compounds, which are interesting candidates for the synthesis of advanced polymers. The terpene-based monomers are usually polymerization in a low activity to give irregular products with low molecular weights via free radical polymerization, cationic polymerization or anionic polymerization. In contrast, coordination polymerization could efficiently initiate the polymerization of terpene-based mononers. Based on this, in this project, (1) the terpenes would be transformed into a series of conjugated diene monomers. According to their structural characters, a series of rare-earth metal complexes would be synthesized by modifying the steric hindrance and electronic effects of coordinating ligands and choosing suitable rare-earth metal elements. The terpene-based monomers would be polymerized into a variety of plastics and elastomers with high molecular weights and high stereo-tacticity in a living mode. (2) ABA-type triblock TPE and comb TPE could be generated by using coordination polymerization (and anionic polymerization) of terpene-based monomers with isoprene, butadiene, styrene or α-methylstyrene etc. (3) The influence of the compatibility between soft and hard segments, the length of each block, the content of hard segment on the properties of TPE such as micromorphology and the tensile strength, tensile modulus and the elongation at break would be studied.

面对石油、煤炭等石化资源终将枯竭的现实，开发生物基聚合物已成为满足人类对高分子材料需求的唯一选择。萜烯储量丰富、种类众多，可用于制备聚合物。使用自由基、阳离子、阴离子等方法聚合萜烯，存在聚合活性和产物分子量低、无立构选择性、易交联等问题。而配位聚合方法可有效解决以上问题。本项目：①拟将萜烯转化成萜烯基共轭双烯烃，针对每种萜烯基单体独特的结构特点，通过调控配体空间位阻、电子效应及金属元素，合成一系列高催化活性和立构选择性的催化剂，实现萜烯基共轭双烯活性聚合，制备高分子量、立构规整的萜烯基塑料和弹性体。②将萜烯基共轭双烯与异戊二烯、丁二烯、苯乙烯、α-甲基苯乙烯相匹配，采用配位聚合或与阴离子聚合法相结合，制备立构规整ABA-型和梳型热塑性弹性体（TPE）。③研究该新型TPE软硬段的相容性、各嵌段长度、硬段含量等结构因素，对TPE微观形貌、拉伸强度与拉伸模量和断裂伸长率等物理力学性能的影响规律。

高分子材料已经遍布人类生产、生活的方方面面，已经成为人类生活不可或缺的重要组成部分。然而，面对石化等非再生资源终将枯竭的现实，开发可再生生物基聚合物已经成为应对人类对高分子材料日趋增长的需求唯一选择。萜烯等生物基化合物种类繁多、结构各异，需要根据其结构特点匹配相应的催化剂，将其转变成立构规整、组成序列可控的高分子材料。本项目主要开展了如下研究：（1）利用限制几何构型稀土催化剂实现了1-苯基-1,3-丁二烯（1PB）高间规立构3,4-选择性均聚合，通过双选择性非茂稀土催化剂制备出了间规立构3,4-聚1PB和高顺1,4-聚异戊二烯的两嵌段共聚物。（2）4,8-二甲基-1,3,7-壬三烯（DMNT）被两类稀土催化剂转化为1,2-和反式1,4-立构规整的聚DMNT弹性体。（3）通过催化剂结构设计与优化，制备出了乙烯与对甲氧基苯乙烯以及其它苯乙烯衍生物的交替共聚物。（4）根据苯乙烯类单体的结构特征，选用适当的稀土催化剂，实现了烯丙基苯乙烯、炔基苯乙烯、乙烯基萘、乙烯基硼氮杂萘等单体间规立构均聚合及其与苯乙烯的无规共聚合。（5）通过电子效应调控，将对苯乙烯聚合呈惰性稀土催化剂转变为高活性、链转移催化体系，制备出低分子量聚苯乙烯。（6）优化出使SBS热塑性弹性体力学性能最佳的成型工艺；制备出聚乙烯与乙丙橡胶构成的热塑性弹性体。总之，通过本项目建立起了催化剂结构与单体聚合行为之间的关系，为生物基高分子材料开发以及可循环利用弹性体的设计与制备打下了重要基础。