基于双重可逆非共价键构筑高强高韧室温快速自修复弹性体及性能研究

Self-healing elastomer is the key material in the future development of flexible electronic, national defense and medicine. However, the high strength, high toughness and fast self-healing at room temperature could not been achieved at the same time, which hinders the development of the self-healing elastomer products. To solve the contradictory between the mechanical property and the self-healing property, we will introduce multiple hydrogen bonding and metal-ligand interactions into polymer. The multiple hydrogen bonding can induce microphase separation and the dual dynamic interactions will act as reversible sacrificial bonds, which will increase the strength and toughness of materials. Besides, the high content of the reversible cross-linked bonds will also facilitate self-healing. Hence, the contradictory may be balanced and the self-healing elastomer with high performance will be prepared. Firstly, we will choose the dynamic interactions and design the polymer structures and then investigate the relationship between polymer structure (molecular weight, content and distribution of dynamic bonds) and the microphase separation. Secondly, the breaking-recombining of the reversible bonds in the cross-linked network under load will be studied to reveal the mechanism of the improved strength, toughness and self-healing by the microphase separation and dual dynamic interactions. We will establish the design principles of the fast self-healing elastomers with high performance to adjust the mechanical property and self-healing property as required. This project will establish a new preparation technology for self-repairing elastomers with high performance and provide new materials and technical support for practical applications.

自修复弹性体是未来柔性电子、国防军事及医疗发展的重要材料。高强度、高韧性及室温快速自修复无法兼顾的问题是制约自修复弹性体产品开发的瓶颈。为解决力学性能与自修复性能难以协调的问题，本项目提出将多重氢键和金属配位作用同时引入聚合物，利用氢键诱导的微相分离和双重可逆牺牲键实现力学性能增强增韧，同时高含量可逆动态键促进快速自修复的设计思想，使相互制约的矛盾达到合理平衡，制备高强高韧室温快速自修复弹性体。拟从可逆动态键的筛选和聚合物结构设计出发，研究聚合物结构因素（分子量、动态键含量及分布）对微相分离结构的影响规律，结合载荷作用下交联网络中可逆键的断裂-重组条件，揭示相分离结构和双重可逆键协同实现弹性体增强增韧及快速自修复的作用机制。提出具有快速自修复高强高韧弹性体的设计原则，实现力学性能和自修复性能的可控调节，建立新型自修复高性能弹性体制备新技术，为实际应用提供新材料和技术保障。

兼具高强度、高韧性与快速修复性是自修复弹性体制备和应用面临的关键难题。本项目通过聚合物结构设计，引入双重可逆动态键，并构筑微相分离结构，揭示微相分离结构和可逆交联网络对弹性体力学性能和自修复性能的影响机制，制备出高强度、高拉伸性的快速自修复弹性体。主要研究内容包括：（1）首次提出将新型可逆非共价键均苯三酰胺（BTA）基元和咪唑-Zn2+动态配位作用同时引入丙烯酸酯聚合物中，通过BTA诱导的微相分离结构和双重可逆动态交联键，实现弹性体力学性能和修复性能的调节。研制的弹性体的拉伸断裂强度和断裂伸长率达到了5.2 MPa、551%，表面划痕在60℃、6 h内可自愈合。（2）设计合成了一种具有多相结构的氢键自修复ABA三嵌段丙烯酸酯弹性体。A嵌段具有高密度氢键位点，可保持材料的宏观形状并阻碍分子链的滑移，B嵌段具有低密度氢键位点，主要用于耗散能量、实现材料增韧。由于氢键密度的分区分布的设计，研制的弹性体的机械性能提升显著，拉伸强度为20.96 MPa，韧性达77.06 MJ/m3。切断后的样品在室温下修复24 h后，拉伸强度恢复率达93%。（3）基于硫代内酯基元的双重功能化特性，合成了含有高密度双重动态键的聚氨酯弹性体。研制的含有二硫键和咪唑-Zn2+配位作用的聚氨酯-脲弹性体的拉伸断裂强度高达44.06 MPa，断裂伸长率为1000%，韧性为181.93 MJ/m3。与单一动态键相比，双重动态键的引入可同时显著提升材料的强度和韧性。聚氨酯弹性体表面划痕在室温24 h内可自动愈合，通过稍微升温（如60℃或80℃），切断-拼接的弹性体的力学性能修复率可达90%以上。本项目的研究为高性能快速自修复弹性体的设计提供了新思路，为这类材料的应用提供了理论依据和技术储备。