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

Theproduction of industrially scalable conductive polymer-basedcomposites (CPCs), with tailored physicochemical properties, suchas anisotropic conductivity, has proved a formidable challenge innanoscience and nanotechnology. This is because the final performanceof such CPCs dramatically depends on the distribution and type ofpolymer matrix, the degree of spatial ordering, and the material'spercolation threshold. By adjusting the concentration of single-walledcarbon nanotubes (SWCNTs) within a hot-drawn poly(vinyl alcohol) (PVA)composite, we show that a 10-fold increase in the CPC's conductivityand a four-fold increase in its anisotropy may be obtained. Usinga combination of Raman spectroscopy, density functional theory (DFT),and nonequilibrium Green's function (NEGF)-based methods, wedevelop a general ab initio model, which describes qualitatively andsemiquantitatively the measured conductivity of our PVA/SWCNT CPCs.The success of this model shows that the CPC's conductivityis determined by (1) the connectivity of the SWCNT network withinthe polymer matrix, (2) the hopping resistance to intertube conductance,(3) the concentration of SWCNTs in the sample, and (4) the amountof stretching and concomitant orientational order parameter of theSWCNTs in the composite. Our combined experimental and theoreticalapproach provides a means for designing CPCs with given anisotropicconductivities based on SWCNTs within different polymer matrices andshould prove highly relevant to a broad academic and industrial communityinterested in nanomaterial design.