基于液晶-半结晶（PBDPS-PCL）共聚物的双向形状记忆材料的制备及性能研究

Two-way shape memory semi-crystalline polymer networks that can perform reversible expansion and contraction shape change as human muscles under stimulation have been the focus of attention in the past five years. Currently, two-way shape memory semi-crystalline polymer networks have multi-phase or broad melting temperature. The actuation domain was the low-melting-temperature crystal phase. In this case, the reversible strain of semi-crystalline polymer networks is ~20%, which are much less than liquid crystal networks. . This project aims to open a new path to prepare two-way shape memory copolymers by combining both liquid crystalline polymer (PBDPS) and polycaprolactone (PCL). According to molecular design, liquid crystalline polymer (PBDPS) has the capacity of nucleation, and it can enhance crystallinity, and accelerate crystallization speed of polycaprolactone. First, PBDPS-b-PCL block copolymers are synthesized, where liquid crystalline polymer (PBDPS) with high melting temperature can act as anisotropic skeleton and induce epitaxial crystallization of polycaprolactone. In this case, PCL phase shows two-way shape memory effect. Moreover, two-way shape memory copolymer networks can be obtained by stretching copolymer first and then dynamic crosslinking with disulfide bonds. In this way, monodomain liquid crystalline networks show reversible shape memory effect. In this case, both liquid crystalline component and polycaprolactone component have the potential of reversible shape memory effect. Therefore, copolymer networks will show reversible triple-shape memory effect. Meanwhile, dynamic covalent bond will endow copolymer networks self-healing effect. In addition, the influence of structure and ratio of liquid crystalline polymer and polycaprolactone on the crystallization, melting, liquid crystal phase transition behaviors, and the influence of stretching strain, crosslinking density, and topology on the reversible strain, response and self-healing behaviors will be investigated systematically. . Compared with current two-way shape memory polymers, this smart materials have the advantages of multi-reversible and complex shape change, high reversible strain and self-healing effect, which will open new avenues of study for the design and further application of two-way shape memory polymers.

双向形状记忆半结晶聚合物材料在外界刺激下，能够模仿人体肌肉可逆伸缩，成为近年来国内外研究的热点。本项目另辟蹊径将具有成核作用的液晶聚合物（PBDPS）与聚己内酯（PCL）共聚制备双向形状记忆高分子材料。PBDPS（高熔点相）作为各向异性骨架，诱导PCL（低熔点相）附生取向结晶，赋予PCL双向形状记忆功能。进一步，利用先取向后动态交联两步法制备PBDPS-co-PCL交联网络。液晶、结晶组分同时具有双向形状记忆功能，赋予交联网络双重双向形状记忆功能；动态共价键赋予交联网络自修复功能。通过探讨PBDPS、PCL组分结构、比例，交联密度、交联拓扑结构对PBDPS-PCL共聚物的热性能，结晶、熔融、液晶相变行为以及可逆应变大小，响应行为的影响规律，建立结构与性质的关系。和传统双向形状记忆半结晶聚合物材料相比，本项目制备的PBDPS-PCL共聚物具有多重响应、可逆应变量大、自修复、复杂变形等优势。

双向形状记忆半结晶聚合物材料在外界刺激下，能够模仿人体肌肉可逆伸缩，成为近年来国内外研究的热点。本项目将具有成核作用的液晶聚合物（PBDPS）与半结晶聚合物（聚己内酯、聚乙二醇）共聚制备双向形状记忆高分子材料。高熔点液晶相PBDPS作为各向异性骨架，诱导低熔点半结晶聚合物附生取向结晶，赋予其双向形状记忆功能。重点研究了液晶聚合物自身双重形状记忆效应以及液晶PBDPS-PCL和PBDPS-PEG多嵌段共聚物中PBDPS、PCL、PEG组分结构、比例对共聚物的热性能，结晶、熔融、液晶相变行为以及可逆应变大小，响应行为的影响规律，建立结构与性质的关系。研究结果发现，液晶PBDPS经过取向拉伸后，侧基苯环堆积相互作用可以作为物理交联点，固定取向结构赋予其双向形状记忆功能。嵌段共聚物经过拉伸取向后，液晶嵌段部分可以作为取向骨架诱导半结晶组分取向结晶，实现双向形状记忆。和传统双向形状记忆半结晶聚合物材料相比，本项目制备的液晶-半结晶共聚物具有多重响应、可逆应变量大、复杂变形等优势，为新型双向形状记忆半结晶聚合物的制备提供研究思路。