An electrically conductive polymer composite with a co-continuous segregated structure for enhanced mechanical performance

Abstract

Conductive polymer composites (CPCs) with segregated structures can achieve excellent electrical conductivity with low conductive filler, however, the weak interfacial adhesion always impairs their mechanical performance and limits the practical applications. Herein, we developed a carbon nanotube (CNT)/thermoplastic polyurethane (TPU) composite containing a novel co-continuous segregated structure, with a highly continuous TPU region and highly continuous CNT network among the interfaces of the TPU region, via the utilization of a 3D printed TPU skeleton. The electrical conductivity and mechanical performance were simultaneously improved. The co-continuous segregated CNT/TPU composite with only 4.0 wt% CNT achieves a superb electrical conductivity of 46.7 S m⁻¹, which is 83% higher than that for the CNT/TPU composite with a conventional segregated structure. The tensile strength and the elongation at break of the co-continuous segregated CNT/TPU composite are 18.1 MPa and 281%, exhibiting 389% and 1238% enhancements in comparison to 3.7 MPa and 21% for the conventional segregated structure. Our work reveals a new methodology, i.e., the construction of a co-continuous segregated structure with a highly continuous polymer region and highly continuous conductive networks composed of interfacial distributed conductive fillers, to address the trade-off between electrically conductive performance and mechanical performance in CPCs, which can be extended to almost all other 3D-printed continuous polymer skeletons and even other 3D continuous polymer matrices (e.g., melt spun or mechanically woven 3D fabric).