Fabrication of open-cell thermoelectric polymer nanocomposites by template-assisted multi-walled carbon nanotubes coating

In this work, open-cell polyvinylidene fluoride (PVDF) templates were employed to assist the formation of multi-walled carbon nanotubes (MWCNT) network in polymer matrices. The continuous network of MWCNT coating and the macro-porosity helped to simultaneously promote the electrical conductivity and suppress the effective thermal conductivity of organic thermoelectric (TE) materials, and thereby enhance their TE conversion efficiencies. In-situ polymerization of polypyrrole during the template-assisted nanotube coating process also promoted the Seebeck coefficient of the polymer nanocomposites by two-fold, while suppressing their electrical conductivity. An optimum ZT value of 1.4 x 10(-5) was achieved for PVDF/MWCNT nanocomposite foams with loaded 24.9 wt% MWCNT. A series of parametric experiments were performed in this study to investigate the effects of open-cell morphology, nanotubes content, and polypyrrole-nanotube interfaces on TE properties of organic materials.