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受自然界生物可以自动愈合伤口的启发,科学家设计出能够自动修复损伤的自修复材料。由于微胶囊体系的制备工艺简单、应用范围广、对多种损伤形式均可修复,受到了科学家的广泛关注。其主要修复过程为:裂纹扩展使微胶囊破裂,微胶囊内的修复剂流到微裂纹处,在催化剂作用下修复剂发生聚合反应从而修复微裂纹。这一过程中修复反应是实现材料自修复的关键,它必须能够在室温下将低粘度液体转变为坚韧的热固性高聚物。本文综述了针对微胶囊自修复材料的修复反应,重点介绍了环烯烃的开环易位聚合、环氧树脂的开环聚合、溶剂的再固化、点击化学四类反应。其中,点击化学由于简单高效的特点成为设计自修复材料的新方法,包括叠氮化物-炔烃反应、共轭二烯和亲二烯体反应、疏基-烯反应、疏基-氰酸酯反应等。通过对比分析修复反应的机理和自修复效率的影响因素,指出各种修复反应的优点和局限性,并对微胶囊自修复材料的发展趋势进行展望。
Inspired by the fact that nature’s creatures can heal wounds automatically, scientists have designed self-healing materials that automatically repair the damage. Due to the simple preparation process of the microcapsule system and the wide range of applications, various damage forms can be repaired, attracting wide attention of scientists. The main repair process is as follows: the microcapsule is cracked by the crack propagation, the repairing agent in the microcapsule flows to the microcrack, and the repairing agent undergoes a polymerization reaction under the action of the catalyst to repair the microcrack. The repair reaction in this process is the key to material self-healing, and it must be able to convert low viscosity liquids to tough thermoset polymers at room temperature. This review summarizes the repair reactions of microcapsule self-healing materials, and focuses on the ring-opening metathesis polymerization of cycloolefins, the ring-opening polymerization of epoxy resins, the re-solidification of solvents and the click chemistry. Among them, click chemistry has become a new method for designing self-repairing materials because of its simplicity and high efficiency, including azide-alkyne reaction, conjugated diene and dienophile reaction, sparse base-ene reaction and sparse-cyanate reaction Wait. By comparing and analyzing the mechanism of the repair reaction and the influencing factors of the self-healing efficiency, the advantages and limitations of the various healing reactions are pointed out, and the development trend of the self-healing materials of the microcapsules is prospected.