Flexible and lightweight porous polyether sulfone/Cu composite film with bidirectional differential structure for electromagnetic interference shielding and heat conduction

Abstract

Lightweight porous conductive polymer composite materials (CPCs) are up-and-coming electromagnetic interference (EMI) shielding materials. However, fair-sized thickness (>1 mm) and limited thermal conductivity hinder their application in modern integrated and miniaturized electronics. Herein, flexible bidirectional differential porous carbon fillers (C-fillers)/polyether sulfone (PES)/Cu (PCPES/Cu) composite films are fabricated via phase inversion technology followed by magnetron sputtering process. The bidirectional differential structure features with a top porous C-fillers/PES (PCPES) film and a bottom sputtering highly-conductive Cu thin layer. The PCPES film possesses hierarchical pore structure that is derived from mass transfer between solvent and nonsolvent. Owing to the bidirectional differential structure, an “absorption-reflection-reabsorption” shielding process is created to strengthen EMI shielding performance and relieve secondary microwave reflection in PCPES/Cu composite film. Its shielding effectiveness is as high as 59.7 dB, and specific SE/t is up to 6982.5 dB cm2 g−1. Notably, the reflection coefficient falls to 0.73, below other shielding materials with similar thickness. Further, the Cu thin layer can construct effective transmission channel of phonons in the plane direction, allowing thermal conductivity enhancement. The flexible lightweight EMI shielding composite films with satisfied thermal conductivity have extensive application prospects, such as aerospace, wearable electronics, and portable electronics.