Microstructure and electrical conductivity of CNTs/PMMA nanocomposite foams foaming by supercritical carbon dioxide

Abstract

The carbon nanotubes (CNTs)/ polymethylmethacrylate (PMMA) nanocomposite foams were prepared by the anti-solvent precipitation and supercritical foaming method. The morphology and the electrical conductivity of the foams with different kinds of CNTs were investigated. The experimental results showed that all the foams had uniform cell structure, and the cell size changed from 1.9 to 10 μm when the foaming temperature ranged from 50 °C to 95 °C. With small cell size (1.9–4.0 μm), the conductivities of the foams were 3.34×10⁻⁶–4.16×10⁻⁶ S/cm compared with the solid matrix since the introduction of micro cells did not destroy the conductive network. However, when the cell size was biger (4.5–10 μm), the aspect ratio of the CNTs played the dominant role of the conductivity. The foams with short CNTs had higher conductivity, since the short CNTs were hard to stretch and snap by the cells and can well-dispersed in the cell wall and cell edges. The results of this work provided a novel material design method for conductive foams based on the rule of both microstructure and aspect ratio of the CNTs.

Keywords

electrical conductivity / CNTs / supercritical foaming / nanocomposite foams

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