Designing Scalable Anisotropically Conductive Thin\nFilms Using Hot Drawing of Poly(vinyl alcohol)/Single-Walled Carbon\nNanotube Composites

Abstract

The\nproduction of industrially scalable conductive polymer-based\ncomposites (CPCs), with tailored physicochemical properties, such\nas anisotropic conductivity, has proved a formidable challenge in\nnanoscience and nanotechnology. This is because the final performance\nof such CPCs dramatically depends on the distribution and type of\npolymer matrix, the degree of spatial ordering, and the material’s\npercolation threshold. By adjusting the concentration of single-walled\ncarbon nanotubes (SWCNTs) within a hot-drawn poly(vinyl alcohol) (PVA)\ncomposite, we show that a 10-fold increase in the CPC’s conductivity\nand a four-fold increase in its anisotropy may be obtained. Using\na combination of Raman spectroscopy, density functional theory (DFT),\nand nonequilibrium Green’s function (NEGF)-based methods, we\ndevelop a general ab initio model, which describes qualitatively and\nsemiquantitatively the measured conductivity of our PVA/SWCNT CPCs.\nThe success of this model shows that the CPC’s conductivity\nis determined by (1) the connectivity of the SWCNT network within\nthe polymer matrix, (2) the hopping resistance to intertube conductance,\n(3) the concentration of SWCNTs in the sample, and (4) the amount\nof stretching and concomitant orientational order parameter of the\nSWCNTs in the composite. Our combined experimental and theoretical\napproach provides a means for designing CPCs with given anisotropic\nconductivities based on SWCNTs within different polymer matrices and\nshould prove highly relevant to a broad academic and industrial community\ninterested in nanomaterial design.