LAUSR

Combining the stability of chemical crosslinking and the processability of physical crosslinking is a well-established strategy to design new materials with desirable stimuli–responsive properties. Herein, a series of azobenzenebased thermotropic liquid crystalline polyesters were synthesized by introducing mesogenic dial named 4,4ʹ-bis(6-hydroxyhexyloxy) azobenzene (BHHAB), 2-phenylsuccinic acid (PSA), and different contents of 1,2,3-propanetricarboxylic acid (PTA) as the chemical crosslinker. All these polyesters showed good thermal stability and smectic liquid crystalline phase. Wide-angel X-ray diffraction (WAXD) and the fluorescence emission spectra confirmed the existence of π–π stacking interactions as the physical crosslinking in the polymer chains, particularly at the lower content of PTA. However, when the PTA content increased, the chemical crosslinking changed the chain conformation, and thus the intensity of physical crosslinking slackened gradually. Combining the physical and chemical crosslinking, these polyesters showed the thermoplastic processability, thermal shape memory, heat-assisted healing and photo responsive behaviors. Taking advantages of these features, these multiple stimuli–responsive polymers can bring more chances for smart materials such as soft actuator.摘要结合化学交联提供的稳定性和物理交联提供的可热塑加工性可设计得到具有多种刺激响应行为的新材料. 本文以偶氮苯二氧己醇 (BHHAB) 为液晶基元, 与苯基丁二酸(PSA) 和丙三羧酸(PTA) 本体聚合得到一系列液晶聚合物PBHPS-x%PTA, 其中PTA作为化学交 联, 而取代苯基与介晶基元之间的π–π相互作用可提供物理交联. 热分析结果显示这些聚合物具有高的热稳定性并表现出近晶型液晶行 为. 广角X射线衍射(WAXD) 和荧光光谱证实了分子间具有可作为物理交联点的π–π相互作用; 并且随着PTA含量的增加, 化学交联会逐 渐影响分子链构象, 最终破坏物理交联作用. 轻度的化学交联保留了液晶聚合物的可热塑加工性, 而在物理交联与化学交联的共同作用下, 液晶聚合物具有可逆光致形变, 热致形状记忆及自修复性能, 在智能高分子材料领域表现出一定的应用前景.