基于动态亚胺键的高强度聚亚胺的构筑与性质

Conventional thermoset polymers usually exhibit excellent comprehensive properties, but they can only be molded once and cannot be repaired once damage occurs due to the lack of malleability and rehealability, causing the waste of resources and environmental pollution. Given the reversibility of imine bond through imine exchange reaction, imine-linked polyimine dynamers exhibit dynamic and malleable nature. They can be heated and molded multiple times, and display self-healing property upon treatment with water, heat or primary amine. However, compared to conventional thermoset polymers, the variety of polyimines that have been developed so far is still very limited, and their mechanical property, thermostability and environmental resistance cannot meet the requirements of engineering materials. The goal of this project is to design and synthesize bisimide diamine (as macromonomers) by utilizing commercially available dianhydride, which will be integrated into polyimine skeleton by reacting with aldehyde monomer and triamine crosslinkers through imine condensation reaction, thus achieving a novel class of high-performance polyimines with rigid bisimide unit. The dynamic properties (rehealability, remoldability) of the as-prepared polyimines can be aroused under mild conditions by utilizing the primary amine-promoted imine exchange reaction. We will systematically investigate the dependence of the resulting materials’ mechanical property, thermostability and environmental resistance as well as dynamic nature on the monomer structure and loading amount of the bisimide diamine, thus revealing their structure-property relationship. The knowledge gained in this study would not only provide a solid foundation for the development and applications of polyimines with significantly improved mechanical and thermal properties, but also open many new possibilities for future development of novel high-performance, malleable, and rehealable thermoset polymers.

传统的热固性聚合物综合性能优异但不具有可塑性，且制品一旦损坏难以修复，造成了资源的浪费与环境的破坏。聚亚胺动态共价高分子特有的亚胺交换反应致使该类热固性聚合物在保持体系交联的同时可多次成型，并在水、热、伯胺等外界刺激下可表现出优良的自修复特性，但其力学强度、耐热性、耐候性等尚不能满足工程领域的要求。本项目拟以商业化二元酸酐为基础单体，将其与其他功能分子结合制备双氨基双酰亚胺单体，再通过亚胺共缩聚反应构筑分子主链包含刚性酰亚胺基元的聚亚胺材料，以期实现聚亚胺的高性能化，并利用伯胺诱发刚性聚亚胺分子骨架在低温条件下的亚胺交换反应，实现聚亚胺在温和条件下的多次成型及自修复。系统研究双氨基双酰亚胺分子结构及加入量变化对所得聚亚胺综合性能的影响，并阐明结构与物理性能关系。项目研究为提升聚亚胺的综合性能以及深化和拓展聚亚胺的应用领域奠定理论基础，为高性能可自修复智能聚合物材料的构筑提供新的研究思路。

传统的热固性聚合物综合性能优异但不具有可塑性，且制品一旦损坏难以修复，造成了资源浪费与环境破坏。聚亚胺动态共价高分子特有的亚胺交换反应致使该类热固性聚合物在保持体系交联的同时可多次成型，并在水、热、伯胺等外界刺激下可表现出优良的修复特性，但其力学强度、耐热性、耐候性等尚不能满足工程领域的要求。本项目以商业化二元酸酐为基础单体，将其与其他功能分子结合后制备了系列不同分子结构的双氨基双酰亚胺单体，通过“预聚合”与“溶剂退火”合成方案构筑了系列不同取代基、不同酰亚胺基元含量的高性能聚亚胺薄膜材料，将聚亚胺材料的玻璃化转变温度从文献报道的40-120 °C提升到230-270 °C，拉伸强度提高至100 MPa以上，拉伸模量达到2.3 GPa左右，同时具有优良的断裂韧性、高的热分解温度、低的吸水率、优良的抗蠕变特性以及良好的耐水解稳定性。本项目利用伯胺诱发刚性聚亚胺分子骨架在80 °C下的亚胺交换反应，实现了聚亚胺在温和条件下的再次成型与再修复。通过系统研究，揭示了双氨基双酰亚胺分子结构及加入量变化对所得聚亚胺综合性能的影响规律，阐明了聚亚胺材料的结构与物理性能关系，并优化了聚亚胺材料在伯胺催化下的再修复条件。本项目的研究结果证实，将酰亚胺基元引入聚亚胺分子骨架可显著提升聚亚胺材料的综合物理性能同时能保留亚胺键的动态特性。该研究方法可望推广到其他高分子体系，如聚酰胺、聚氨酯、聚脲等，对于实现聚酰亚胺与其他种类高分子在分子尺度的杂化、提升传统高分子的综合物理性能具有重要的借鉴意义。项目研究为提升聚亚胺的综合性能以及深化和拓展聚亚胺的应用领域奠定了理论基础与数据支撑，为高性能可自修复智能聚合物材料的构筑提供了新的研究思路。