Multistructural Network Design Enables Polybenzoxazine to Achieve Low-Loss-Grade Super-High-Frequency Dielectric Properties and High Glass Transition Temperatures
Ming Zeng, Dengru Tan, Zijian Feng, Jiangbing Chen, Xiang Lu, Yiwan Huang, Qingyu Xu
Abstract
An original design strategy for the preparation of thermosetting resins with both super-high-frequency low dielectric constant (k) and low dielectric loss (f) as well as high glass transition temperature (Tg) values is presented. The key to this design strategy is incorporating a bulky group and reactive furan ring to increase the free volume and the cross-linking density, respectively. The formed multistructural networks (relatively dense near furan rings and relatively loose near bulky groups) are beneficial not only for lowering k values but also for maintaining high Tgs of main-chain benzoxazine copolymers. More importantly, the optimized copolymers possess low f values (≤0.008) under 5 and 10 GHz, satisfying the requirement of super-high-frequency communications. The correlations between the free volume and thermal and dielectric properties are also discussed to understand the synergistic mechanism. The work opens a new route for the structural design and preparation of super-high-frequency low dielectric functional polymeric materials.