Supercritical carbon dioxide assisted phase coarsening of double-percolated polycaprolactone/polystyrene/multi-wall carbon nanotube composites for improved electrical performance and electromagnetic interference shielding

Abstract

The continuity of conductive network and conductivity performance in double-percolated conductive polymer composites (CPCs) can be improved after static annealing, though, there are often increased viscosities in CPCs when filler contents increased, making annealing process difficult. Herein, the incompatible polycaprolactone (PCL)/polystyrene (PS) systems were designed to double-percolated PCL/PS/multi-wall carbon nanotube (MWCNT) composites, subsequently, thermal and plasticizing effects during carbon dioxide (CO2) annealing were combined to assist phase coalescence. Benefiting from viscosity reduction, phase coarsening, electrical conductivities and electromagnetic interference shielding effectiveness (EMI SE) of PCL/PS/MWCNT composites were promoted even at 5 wt. % filler content. After supercritical CO2 annealing, percolation threshold decreased from 0.50 wt. % to 0.24 wt. %, and EMI SE increased from 31.8 dB to 39.8 dB, which improved 25 %. This work demonstrates phase coarsening of double percolated CPCs is effectively controlled by CO2 annealing conditions, and the final degree of performance improvement is connected to polymer systems.