A novel intrinsic semi-aromatic polyamide dielectric toward excellent thermal stability, mechanical robustness and dielectric performance

The development of aliphatic polyamide as dielectric polymer is limited due to relatively high dielectric loss, low breakdown strength and low servicing temperature. Different from the traditional ways for enhancing the dielectric properties of aliphatic polyamides by compositing with inorganic materials, here an alternative strategy is reported via random copolymerizing aliphatic polyamide with semi aromatic polyamides as functional segments. The designed co-polyamide shows decreased dielectric loss of 0.04 and enhanced breakdown strength of 319 MV/m with a low content of semi aromatic polyamides. Moreover, taking advantage of the inherent rigid benzene ring and flexible aliphatic chain, high glass transition temperature and great toughness are achieved simultaneously in the prepared semi aromatic polyamides. The introduction of aromatic segments has also improved dielectric and mechanical properties of co-polyamide at elevated temperature (150 °C), which is desirable and crucial for polymer dielectrics. The strategy provides new possibilities for the development of high-performance intrinsic polymer dielectrics.