基于热可逆Diels-Alder反应的自修复环氧树脂的构建及多重修复机制研究

Local damage and micro-crack might produce during processing and usage of thermolsetting resins as a result of thermal and mechanical fatigues. It is difficult to detect and repair these micro-damages due to the limitation of materials character and product shape. Over time, some problems will cause, such as structure breakage, decrease of mechanical properties, and shortened material lifetime. Such problems can be overcome essentially by developing the remendable thermolsetting resins via simulating the mechanism of organism repair themselves when damaged. In this research, based on the thermoreversible Diels-Alder reaction, a kind of remendable epoxy resin with controlled strength and toughness is expected to be constructed by in-situ introducing nano-particles and thermoplastic resin into epxoy resin. By exploring the kinetics of Diels-Alder reaction and retro-Diels-Alder reaction, the rule of thermoreversibility of the epoxy resin under the synergistic action of nano-particles and thermoplastic resins can be made clear, and then the synergistic reinforcing/toughening effect of nano-particles and thermoplastic resins on the thermoreversible self-healing epoxy resin can be elucidated. Consequently, the multiple healing mechanisms can be revealed grounded on self-healing of transfer and enriching of nano-particles, diffusion of thermoplastic resin, and thermal reversible Diels-Alder reaction. As a result, the theoretical basis for the self-healing of micro-damages in the epoxy resin with controlled strength and toughness can be provided, and meanwhile, a solid foundation for the safe and normal use and the long-term application of the thermosetting resins can be layed.

在热和机械疲劳等因素的作用下，热固性树脂在加工成型和使用过程中内部会产生局部损伤和微裂纹。因材料性质和产品形状等限制，探测和修复微损伤十分困难，而微损伤的进一步发展会导致材料结构破坏、力学性能下降和使用寿命缩短等问题。模仿生物体损伤自修复的原理，开发具有自修复功能的热固性树脂将从根本上解决这一问题。本课题拟将纳米微粒和热塑性树脂原位引入环氧树脂中，构建强韧性可控、基于热可逆Diels-Alder(DA)反应的自修复环氧树脂。通过探讨DA反应和逆DA反应动力学特性，明确纳米微粒和热塑性树脂共同作用的环氧树脂的热可逆性规律，阐明纳米微粒和热塑性树脂原位增强增韧自修复环氧树脂的协同作用机制，揭示基于纳米微粒迁移富集自修复、热塑性树脂扩散自修复和热可逆DA反应自修复共同作用的多重修复机制，从而为强韧性可控的环氧树脂的微损伤自修复提供理论依据，并为热固性树脂的安全正常使用及长效化应用奠定坚实基础。

在热和机械疲劳等因素作用下，高分子材料在加工成型和使用过程中内部会产生局部损伤和微裂纹，这类微损伤会导致材料结构破坏、力学性能下降和材料使用寿命缩短等问题。模仿生物体损伤自修复的原理，开发具有自修复功能的高分子材料将从根本上解决这一问题。本课题将热塑性树脂、纳米微粒引入基于Diels-Alder反应的热可逆自修复聚氨酯及环氧树脂中，合成了具有良好力学性能和自修复性能的聚氨酯和环氧树脂。对基于Diels-Alder反应的热可逆自修复聚氨酯和环氧树脂的合成和修复行为、纳米SiO2增强热可逆自修复树脂的构建、自修复行为及协同修复机制等进行了详细探索。从而建立通过纳米微粒和热塑性树脂协同增强增韧热可逆自修复环氧树脂的方法，明确了纳米微粒和热塑性树脂协同作用下的热可逆自修复聚氨酯、环氧树脂的DA反应和Retro-DA反应的动力学特性和热可逆性规律。并且指出，热塑性树脂、纳米微粒在改性热可逆自修复聚氨酯和环氧树脂的力学性能的同时，赋予聚氨酯和环氧树脂良好的自修复性能。表明纳米微粒和热塑性树脂在增强增韧热可逆自修复材料中具有协同作用，其修复是通过纳米微粒迁移富集自修复、热塑性树脂扩散自修复和热可逆Diels-Alder反应自修复共同作用而实现的，其中热可逆Diels-Alder反应为高分子材料的修复作出了主要的贡献，而纳米微粒迁移富集和热塑性树脂扩散在高分子材料的修复过程中起到了辅助的作用，其有助于材料修复效率的提升。从而揭示了基于纳米微粒迁移富集自修复、热塑性树脂扩散自修复和Diels-Alder反应热可逆自修复共同作用的多重修复机制，这为强韧性可控的高分子材料的微损伤自修复提供理论依据，并为高分子材料的安全正常使用及长效化应用奠定坚实基础。