Percolation effect and thermoplasticity of conducting [poly(acrylic acid)/C₁₆TAB-modified graphene oxide]_n multilayer films

The feasibility and effectiveness of the electrostatic self-assembly technique are demonstrated for the fabrication of thermoplastically conducting multilayer films. The layer-by-layer self-assembly process is based on the alternating adsorption of low molecular weight (M _n) poly(acrylic acid) (PAA) and cetyltrimethyl-ammonium bromide-modified graphene oxide (GO) with three carbon layers. A unique conductivity percolation effect is observed at a percolation threshold (percolation bilayer number) because the carbon–carbon interlayer can be expanded by the diffusion of PAA molecular chains. The resultant multilayer films show typical positive/negative temperature coefficient effects because of the thermoplasticity of the PAA with low M _n. After being reduced from GO to graphene (G), the electrical conductivity of the resulting (PAA/G)_n multilayer film is dramatically enhanced, and the percolation threshold occurs at a high bilayer number. The reasonable conductivities and the percolation effect make these films inherently interesting and potentially useful as components of advanced electronic devices.