文献名： Magnetically gradient-distributed microcapsule/epoxy composites: low capsule load and highly targeted self-healing performance

作者：Wenxia Sima^a; Qianqiu Shao^a; Potao Sun^a; Chen Liang^a; Ming Yang^a; Ze Yin^a; Qin Deng^b

^a  State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400030, People's Republic of China

^b  Analytical and Testing Center, Chongqing University, Chongqing 400030, People's Republic of China

摘要：One-component self-healing epoxy-matrix composites are needed urgently in the electronics industry because of their ability to repair surface damage autonomously. However, their practical applications are limited by unsuitable external stimuli and heavy microcapsule loads. Here, we report a magnetic-field and ultraviolet dual-responsive microcapsule to endow epoxy composites with a highly targeted self-healing capability under low microcapsule loads. Specifically, 5 wt% Fe₃O₄@SiO₂ nanoparticles that were incorporated into the core material served as magnetic targets and helped the microcapsules to navigate to the near-surface region of a high-failure probability, to form magnetically gradient-distributed microcapsule/epoxy composites. This resulted in a more than fourfold increase in the local microcapsule concentration. The successful targeted self-healing with a microcapsule doping percentage as low as 4 wt% was confirmed by laser-scanning fluorescence confocal microscopy and scanning electron microscopy observations, and electrochemical testing. In addition, a kinetic model based on isothermal photo-differential scanning calorimetry measurements and a molecular-dynamics simulation model were both established to analyze the self-healing mechanism. Because of the facility and universality of this magnetic control method, these magnetic microcapsules could be guided to concentrate in vulnerable parts of other electrical insulators as desired, which highlights the good potential of this targeted self-healing method in energy fields.

关键词：Targeted self-healing; Magnetic control method; Microcapsule; Kinetic model; Molecular-dynamics simulation model