基于醚键极性化端羟基聚丁二烯热固树脂的构筑、结构调控及构效关系研究

Hydroxyl-terminated polybutadiene (HTPB) is widespread used as a matrix resin for low-temperature-resistant composites. However, the major drawback of HTPB is its poor compatibility with polar functional components, which is attribute to its weak polar backbone. Thus, it is a challenging topic to construct HTPB with polar without sacrificing its excellent properties. In this proposal, based on the previous works on construction of polyether-b-polybutadiene-b-polyether triblock copolymers, a series of hydroxyl-terminated polybutenediol were proposed and synthesized by polycondensation reaction using ruthenium complexes or alkali as catalysts, respectively. As the polar ether bond is introduced into the polymer repeating unit, the microstructure can be controlled precisely. Through compare studies on properties, the influence and action mechanism of ether bond introduction forms (introduced into the segments which are local at both ends of HTPB and form block copolymer or introduced into the polymer repeating unit as a polar functional group) and the isomer of unsaturated double bonds (cis-2-butenyl ether, trans-2-butenyl ether, 2-vinyl ethyl ether) on the properties of polymers and elastomers will be revealed. On the basis of this theoretical study, the structure of the polymer will be redesigned, and a novel polymeric matrix material based on polar HTPB will be constructed. The implementation of the proposal can provide new ideas and new methods for the construction of polar HTPB, moreover that can provide theoretical basis for the design of such material structure.

端羟基聚丁二烯（HTPB）是一种应用广泛的耐低温复合材料基体，其存在着分子主链极性弱，与极性功能组分相容性差的固有缺陷。在保留HTPB优异性能的同时，构筑极性化HTPB是一具有挑战性的研究课题。项目在前期构筑聚醚-聚丁二烯-聚醚三嵌段共聚物的研究基础上，提出分别利用钌配合物及碱催化的缩聚反应构筑一系列端羟基聚丁烯二醇，将极性醚键引入聚合物重复单元结构内，同时可实现聚合物微观结构的精确调控。通过一系列性能对比，揭示醚键的引入形式（以嵌段聚合物形式引入HTPB的两端或以极性功能基团形式引入聚合物单元结构内）及不饱和双键的异构体形式（顺式2-丁烯醚、反式2-丁烯醚及2-乙烯基醚）对聚合物及固化后弹性体性能的影响规律和作用机理。在此理论研究基础上，对聚合物的结构进行再设计，构筑新型极性HTPB聚合物基体材料。项目实施不仅为极性HTPB的构筑提供新思路与新方法，更为此类材料结构的设计提供理论依据。

端羟基聚丁二烯（HTPB）热固性基体树脂存在结构中缺乏极性基团，与极性组分相容性差的不足。项目围绕着极性功能化HTPB制备过程中构筑策略的选择、微观结构的调控以及构效关系的建立展开系统研究工作。通过大量高分子合成技术的应用构筑了三类结构的极性功能化HTPB，并实现了极性基团的引入方式及双键的异构形式的调控。通过性能对比，建立构效关系。研究内容及结果如下:①通过钌配合物催化及碱催化缩聚的合成策略构筑了端羟基聚丁烯二醇（PBD），将极性醚键引入聚合物结构单元内。通过改变钌配合物催化过程中的聚合温度以及碱催化过程中单体的异构形式实现了PBD结构中2-乙烯基乙醚及2-丁烯醚顺反异构单元相对含量的调控。②利用开环易位聚合（ROMP）实现HTPB的构筑，并通过巯基-烯点击反应将极性基团引入HTPB的侧链。对比了四种链转移剂（CTA）对聚合行为的影响，结果显示CTA的化学结构对结构中顺反异构单元的相对含量具有显著影响。构筑了三种分子量接近但微观结构存在较大差异的HTPB，用于性能对比。③构筑了聚乙二醇-聚丁二烯-聚乙二醇三嵌段共聚物，将极性醚键引入HTPB的两端。④通过性能对比建立了一系列的构效关系。HTPB体系中顺式1,4-加成结构含量的增大有益于玻璃化转变温度（Tg）的降低，而反式异构体含量的增大导致产物体现出明显的结晶趋向。PBD中2-乙烯基乙醚结构单元的增大导致产物Tg上升，但结晶性减弱。极性基团以侧基形式键入HTPB结构时，导致Tg显著上升。将极性醚键引入聚合物结构单元内，其影响的程度取决于PBD结构中双键的异构形式。极性醚键以嵌段形式键入HTPB两端时，当聚醚分子量较小时其对Tg的影响有限。⑤拓展研究了两类不饱和聚醚的后功能化及潜在应用。项目实施为极性功能化HTPB的结构设计与可控制备提供了新思路与新策略。为端羟基遥爪聚合物的性能设计与优化提供了理论基础。