Interfacial crosslinking enabled super-engineering polymer-based composites with ultra-stable dielectric properties beyond 350 °C

Abstract The polymer composites exhibiting reliable dielectric properties at high temperatures (>300 °C) are urgently required for cutting-edge electronic applications. In the present work, an interfacial reactive agent named 4-aminophxylphthalonitrile (4-APN), was covalently modified on the surface of the multiwalled carbon nanotubes (MWCNTs) to prepare the nitrile-functionalized multiwalled carbon nanotubes (MWCNTs-CN), which was further incorporated into the phthalonitrile end-capped polyarylene ether nitrile (PEN-ph) matrix to fabricate the high-temperature resistant PEN-ph/MWCNTs-CN composites. It was found that through facile heat-treatment, the crosslinked PEN-ph/MWCNTs-CN (7 wt%) composites exhibited a high glass transition temperature of 430 °C and stable dielectric properties (dielectric constant of 22.08 at 1 kHz) up to 350 °C. Meanwhile, the energy storage density of the composite membrane increased from 0.59 to 2.18 J/cm3 with the increase of filler content, showing an increase of 269.5%. The nitrile-functionalization of MWCNTs can not only improve the interfacial compatibility between MWCNTs-CN and PEN-ph matrix resin but also make MWCNTs-CN play a role as a crosslinker to further improve the mechanical, thermal, and dielectric properties of the composites. Therefore, the PEN-ph/MWCNTs-CN composites prepared by interfacial crosslinking reaction in this work will serve as the candidate materials for high-temperature-resistant energy storage applications.