Constructing Fluorine Hybrid Epoxy Polymers with Excellent Breakdown Strength by Surface Fluorination

The inferior breakdown strength of epoxy resin (EP) is one of the greatest barriers which restricts the evolution of advanced electrical equipment and electronic devices. It had been reported that constructing fluorine hybrid polymers was successful in improving the breakdown strength of organic dielectrics. Therefore, in this study, we constructed fluorine hybrid EP with a satisfactory breakdown strength by surface fluorination. It was found experimentally that the fluorination introduced CF_n groups into EP molecules and contributed to a greater trap level and breakdown strength. After fluorination at 80 °C for 1 h, the CF₃ fraction in fluorinated EP was 14.31%, and the breakdown strength was increased by 27.64%, from 427.87 to 546.13 kV/mm. The density functional theory simulations showed that the CF₃ groups increased the maximum of positive Mulliken charge (MPMC) of EP molecules. Compared to pristine EP, after introducing CF₃ groups, the MPMC was increased from 0.655 to 0.973 eV, which was instrumental in constructing electron traps with a greater level. Thus, the charge transport process in fluorinated EP was repressed and contributed to the superior breakdown strength. This study proposed a strategy to exploit EP polymers with greater breakdown strength and could promote the development of advanced insulation dielectrics for power devices.