A multi-step cold plasma process for fine tuning of polymer nanostructuring

The innovative plasma process, developed in this study for highly structured surfaces, consists to gradually decrease the input power during deposition in order to form polymer nuclei while preserving monomer structure. In such a process, the local heating of the surface at the starting high discharge power seems to control the lateral migration of deposited species on the surface. Therefore, the objective of the current work is to control the substrate surface heating in order to achieve the morphology of the polymer (polyaniline), namely the dimensions of the nanostructures. This requires studying the high-power step through the value of the power, its duration and the number of steps. All these parameters are herein examined on both the chemical and morphological structure of the plasma-polymer. The power variation is shown to have a double effect. Indeed, high value at the first step is required for increasing the surface temperature and allowing nuclei formation but a too high power induces a degradation of the formed nanodots. Moreover, the sensitivity to ammonia gas of such textured polyaniline films is examined and compared to smooth polymer layers.