Low roughness, elevated stiffness and thickness-modulated surface nanocomposites based on the controlled deposition of polystyrene nanoparticles

A significant interest in the versatile and controlled fabrication of surface coatings is present nowadays in materials science. Here we present a repeatable and efficient method of obtaining polystyrene (PS) layers based on the use of controlled deposition of polystyrene nanoparticles (PS-NPs) in the strictly defined amount and forming a smooth (RMS below 1 nm) coating by melting them. Due to the dependence between the concentration of the applied nanoparticles and the thickness of the obtained homogeneous layer, it is possible to control the thickness of the PS coating straightforwardly. Moreover, in this technique, the initial solvent is quickly evaporated, which results in coatings with a higher DMT modulus (up to 8 GPa) compared to spin- or dip-coated methods. We have obtained PS layers on silicon, glass, gold and steel substrates and we have shown the application of our method to cover highly-rough patterned surfaces. Finally, our method is time- and cost-effective due to the inclusion of only the simple heating process and no need to use any advanced equipment. The topography and thickness of PS coatings were studied using atomic force microscopy (AFM) and scanning electron microscopy (SEM) and all are in good correlation with the theoretical calculations.