Hydrophobicity and transparency of Al2O3-based poly-tetra-fluoro-ethylene composite thin films using aerosol deposition

Alumina and polytetrafluoroethylene (Al2O3-PTFE) composite films were fabricated by a simple aerosol deposition (AD) process, to confirm its applicability for various display screens requiring water resistant, anti-smudge and easy-to-clean properties. The surface morphologies, hydrophobic properties, and transparencies of the composite films with different PTFE contents, varying from 0.01 to 1 wt% were investigated. As a result, the composite films with over 0.3 wt% PTFE showed a sudden rise in surface roughness and low transmittance, despite having the highest contact angle of 128° at a PTFE content of 0.3 wt%. From the energy dispersive spectrometer analysis, the crash-cushioning effect of PTFE and agglomerated PTFE particles were determined to be major causes of surface roughness and opacity. In contrast, the transmittance showed a tendency to be enhanced, with an increasing PTFE content in the range of 0.01, 0.05, and 0.1 wt% PTFE, respectively. Especially, the film with 0.1 wt% of PTFE had contact angle of 111° and exhibited a high transmittance of over 75%, which was inferred to be an appropriate amount of PTFE, with a high elongation filling up the surface and the internal defects, leading to an enhancement of transparency. Consequently, these results implied that the AD-prepared Al2O3-PTFE composite coatings are promising candidates for various display applications.