<scp>Cross‐linked</scp> poly(benzoxazole‐<i>co</i>‐siloxane) networks with high thermal stability and low dielectric constant based on a new <scp><i>ortho</i>‐amide</scp> functional benzoxazine
Rui Yang, Boran Hao, Lin Sun, Kan Zhang
Abstract
Abstract In this study, an amide functionalized bis‐benzoxazine (AI‐al) has been synthesized using allylamine, ortho ‐amide functional bis‐phenol and paraformaldehyde as raw materials via Mannich condensation. This newly obtained benzoxazine has been used to react with polydimethylsiloxane (PDMS) through hydrosilylation to form poly(benzoxazine‐ co ‐amide‐ co ‐siloxane) (AI‐al‐PDMS) featuring siloxane, amide and benzoxazine as repeating units. The chemical structures of both oxazine ring‐containing monomer and copolymer are confirmed by NMR and FT‐IR spectroscopies. Besides, the thermally activated polymerization behaviors of AI‐al and AI‐al‐PDMS are investigated by DSC, and the subsequent conversion of benzoxazole formation is studied by in situ FT‐IR. Moreover, dynamic mechanical analysis and thermogravimetric analysis are used to determine the thermal properties of the cross‐linked polymers. The resulting cross‐linked poly(benzoxazole‐ co ‐siloxane) derived from AI‐al‐PDMS shows excellent thermal stability (no T g can be observed before 400°C; Td5 of 393°C) and low dielectric constants (2.52–2.13 in the frequency range of 1 Hz to 1 MHz), evidencing its great potential applications in electronic packing, aerospace, and other high‐performance fields.