Aerosol deposition of titanium dioxide on polymeric substrates – influence of substrate properties and processing parameters on the early stages of film growth

Aerosol deposition (AD) enables room-temperature fabrication of polymer ceramic composites, yet the deposition mechanism of ceramic particles onto polymers is not fully understood. In this study, we investigate the growth of TiO2 films deposited by AD on polycarbonate (PC), polyamide 6 (PA6), and high-density polyethylene (HDPE), with steel as a reference material. Key process parameters (gas flow rate, number of scans, scanning velocity, and nozzle-substrate distance) are varied. Film thickness, surface roughness, and cross-section morphology (prepared by focused ion beam milling) are analyzed by laser scanning microscopy, atomic force microscopy, and scanning electron microscopy. The results reveal pronounced differences between polymer and steel substrates and between the various polymers. Faster initial film growth on PC compared to PA6 and HDPE suggests that further thermal and mechanical substrate properties besides hardness, e.g. the glass transition temperature Tg and the toughness of the substrate, affect the deposition process. Furthermore, polymer substrates exhibit a non-linear dependence of film thickness on gas flow, indicating a narrower deposition window than on steel, especially in the early stages of film formation.