Efficient electrical conductivity and electromagnetic interference shielding performance of double percolated polymer composite foams by phase coarsening in supercritical CO2

There is a growing interest in porous conductive polymer composites (CPCs) in view of lower density and more sufficient material utilization than solid counterparts, but they are still limited by poor performance. Few measures have been taken to deal with the problem by now. Herein, double percolated structure, supercritical carbon dioxide (scCO2) annealing treatment and scCO(2) foaming were first combined to fabricate polystyrene (PS)/poly (methyl methacrylate) (PMMA)/multi-wall carbon nanotube (MWCNT) composite foams with porous double percolated structure. Due to the effective phase coarsening in scCO2 before foaming, the composite foams with density of 0.49 g/cm(3) exhibited excellent electrical conductivity of 2.69 S/m and electromagnetic interference shielding effectiveness of 25.30 dB at thin thickness of 2 mm and low MWCNT loading of 2 vol%. In addition, absorption was the dominant shielding mechanism. For composite foams, the percolation threshold decreased from 0.14 vol% to 0.07 vol% after phase coarsening in 180 degrees C scCO(2). This work provides a green and versatile method for preparing porous CPCs with double percolated structure and improved electrical conductivity.

Automated summary

A green and versatile method involving double percolated structure, supercritical carbon dioxide (scCO2) annealing treatment and scCO2 foaming was used to fabricate porous conductive polymer composites (CPCs) with improved electrical conductivity. The composite foams showed excellent properties with low density, high electrical conductivity, and effective electromagnetic interference shielding effectiveness, mainly through absorption mechanism.