Polypyrrole film formation using DC biasing of substrate in in-solution plasma process

Beyond the existing in-solution plasma (iSP) process used for nanoparticle synthesis, polymer film synthesis has recently been demonstrated via iSP, which occurs at a specific cycle in a substrate with electrical potential. Herein, we propose an iSP reactor designed to tune the characteristics of polypyrrole (PPy) films by applying varied DC biases to the substrate during the solution plasma process. Applying DC bias to the substrate notably enhances the iSP during the negative cycle, thereby generating ionic precursors from pyrrole monomers for PPy film formation. These films demonstrated morphological variances as a function of the applied VDC. At a low voltage (VDC = 0.5 kV), a uniform film was formed via a layer-by-layer growth mechanism, and as the voltage was increased, the film exhibited a structured morphology. Specifically, at VDC = 0.5 kV, the PPy film was successfully coated onto a finely patterned electrode. The proposed iSP process, under specific DC biasing conditions, enables polymer coating without necessitating additional chemicals, catalysts, or masks. This method holds potential for a wide range of applications.