Constructing a double-percolated conductive network in a carbon nanotube/polymer-based flexible semiconducting composite

Conductive polymer composites featuring double-percolated network structures have attracted widespread interest. Constructing such a structure and controlling the trans-phase migration of the conductive filler remain the main challenges for the application of these conductive polymer composites. In this study, we report a novel two-step “in situ microfibrillation” and “microfiber coalescence” strategy that includes melt-drawing and a compressive annealing process to achieve a stable, double-percolated network of a polybutene-1 (PB-1)/polystyrene (PS)/multiwalled carbon nanotubes (MWCNTs) ternary system. Triggered by the compressive annealing treatment, inter-fiber coalescence led to the formation of an interconnected network, resulting in excellent conductive performance (volume resistivity down to 4.6 × 103 Ω·cm) with a MWCNT dosage as low as 1 wt%. Surface energy calculations and experimental evidence both indicated that the selective distribution of the MWCNTs in the PS phase resulted from the preferential surface wetting behavior and π-π interactions between the MWCNTs and PS, which also immobilized the MWCNTs, even at elevated temperatures. This work established a facile and scalable technology for constructing double-percolated structures in multiphase systems, thus providing access to intriguing functionalities and applications.