A novel interpenetrating segregated functional filler network structure for ultra-high electrical conductivity and efficient EMI shielding in CPCs containing carbon nanotubes

Abstract

Inspired by the hierarchically dendritic structure of plant root and its extraordinary ability of grabbing soil, polyurethane (PU) fibers with such bio-mimic structure were fabricated by non-solvent induced precipitation under turbulent force to grab multi-walled carbon nanotubes (CNTs) in this work, forming interpenetrating segregated network (IPSN) with CNTs coated on hierarchically dendritic polyurethane (PU) fibers (HDPUFs) and filled into voids between entangled HDPUFs. Prepared CNT/PU composites illustrate an ultrahigh maximum CNT loading of 80 wt% with good flexibility, while only 10% could be achieved for common segregated structure. Meanwhile, a low percolation threshold of 0.25 wt% and a maximum conductivity of 25 S/cm is achieved. Benefiting from significantly reduced insulating polymer coating on CNTs, the electrical conductivity of CNT/HDPUF composites at low CNT loading (≤7 wt%) is orders of magnitude higher than that of CNT/PU composites containing randomly dispersed CNTs with similar filler content. Simultaneously, the specific electromagnetic interference (EMI) shielding efficiency (SE) of CNT/HDPUF composite reaches up to 10526.1 dB cm2/g thanks to their high electrical conductivity and low density, which has been rarely reported previously for CNT-based composites. This work provides a simple and low-cost method to fabricate thin, lightweight, and flexible composite with high filler content, high electrical conductivity and outstanding electromagnetic shielding performance.