Silane-hybridized polyphenylene oxide for electronic packaging and extreme-environment-resistant multi-functional coatings

Polyphenylene oxide (PPO), as one of the significant low-dielectric resins, plays a critical role in the electronic packaging of 5.5G/6G communications and artificial intelligence. However, the high-performance application of PPO is limited by its thermoplastic nature. Designing PPO with thermosetting characteristics while enhancing its thermal resistance, low dielectric properties and processability posed a critical challenge. Herein, a novel ambient moisture-curable silane-modified PPO (SLPPO) was designed and synthesized through precisely grafting diallylamine onto the backbone of PPO, and followed by efficiently coupling with γ-mercaptopropyl trimethoxysilane (MPTMS). SLPPO presented high self-crosslinking density, as well as processability and formability characteristics at ambient temperature. The intrinsically non-polar rigid backbone and densely crosslinked non-polar silane side chains imparted ultralow dielectric properties to the thermoset (SLPPO₁₉DBT, where DBT was the catalyst dibutyltin dilaurate), concurrently enabling synergistic enhancements in thermal resistance (T_g of 263.8 °C), low-dielectric performance (D_k = 2.40, D_f = 0.0017, 10 GHz) and exceptional flame retardancy. In addition, the toughness of SLPPO can be tailored feasibly by incorporating bis(hydroxyl-terminated) polydimethylsiloxane via an in-situ reaction-mediated phase separation. Furthermore, we further engineered two application formats: printed circuit boards prepreg and extreme-environment-resistant superhydrophobic coatings. This work provides an insight for transforming thermoplastics into functional thermosets, extending promise for their applications in electronic packaging.