Insulating Silicones Based on Dynamic Hindered Urea Bonds with High Dielectric Healability and Recyclability
Wenjie Sun, Jiaming Luo, Lei Zhang, Yue Chen, Pengxin Li, Yiting Zheng, Yonghong Cheng
Abstract
Silicone-containing dynamically hindered urea bonds are developed as a smart insulating material for power equipment and electronic devices. In this work, silicones are constructed by isocyanate–piperazine-based dynamic bonds with cross-linking degree adjusted by glycerol. Healing and recycling based on dielectric and insulating properties are mainly emphasized in this study. We find that dynamic bonds not only heal the cut-damaged feature of the silicone but also enable dielectric property recovery. A healing efficiency above 95% and a recycling efficiency above 90% based on insulation performance are achieved. After recycling, cross-linked silicone exhibits only a slight variation in permittivity and tan δ, while linear silicone shows an apparent increase. Insulation performance of materials with different cross-linking agent concentrations is also investigated. A higher cross-linking degree was found to further improve insulation properties but reduces the recycling efficiency. Importantly, the developed silicones exhibit high intrinsic insulation properties, comparable to commercial silicone materials, which are very attractive for electrical applications.