Highly conducting multilayer films from graphene nanosheets by a spin self-assembly method

Abstract

This article reports a simple, versatile approach to the fabrication of high conducting multilayer films composed of alternating graphene (G) nanosheets and poly(sodium 4-styrenesulfonate) (PSS) using an electrostatic spin self-assembly technique. G nanosheets were prepared from natural graphite by oxidization, expansion, exfoliation, reduction and modification with cationic surfactant cetyltrimethylammonium bromide (C(16)TAB) and anionic surfactant sodium dodecyl sulfate (SDS). The growth process of the (PSS/G(+)/G(-))(n) multilayer films was characterized by UV-vis spectroscopy. Absorbance plotted against the number of bilayers exhibited a linear dependence, indicating a progressive and uniform deposition process of the multilayer films. Higher rotation speeds (omega) can be used to fabricate thinner films, and the G content is in direct proportion to omega(-1/2). The prepared (PSS/G(+)/G(-))(n) multilayer films exhibit an attractive electrical conductivity in the range of 80-110 S cm(-1). When the film thickness overcomes the effect of surface roughness and film morphology, a percolation effect is observed at the percolation threshold. The effects of the number of bilayers on the electrical properties of the ultrathin films are investigated in detail. The results show that the conductivity and percolation threshold can be controlled by adjusting the PSS/G(+)/G(-) ratio, rotation speed, and size of G nanosheets.