Effect of chemical modification on superhydrophobic properties of CT3 steel surfaces

This study systematically explores the influence of diverse chemical surface modifications on the water-repellent properties of CT3 steel substrates, focusing on the synergistic relationship between surface topography and chemical composition in realising superhydrophobic behaviour. Initially, steel samples were coated with a ZnO layer to significantly enhance surface roughness, serving as a foundation for subsequent chemical treatments. The surfaces were then functionalised with various low-surface-energy agents, including triethoxymethylsilane (MTES), polydimethylsiloxane (PDMS), 1H,1H,2H,2Hperfluorooctyltriethoxysilane (PFOS), stearic acid (SA), and high-density polyethylene (HDPE). Quantitative assessment via contact angle measurements demonstrated that coatings of MTES, PFOS, PDMS, and SA successfully achieved superhydrophobicity, characterised by water contact angles greater than 150° and minimal contact angle hysteresis. Of particular interest, MTES treatment in toluene solvent not only effectively reduced the surface free energy but also promoted the formation of nanofilamentous microstructures, thereby amplifying surface roughness and hydrophobic performance. The chemically and morphologically modified surfaces were thoroughly characterised using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and detailed wettability analyses to correlate surface structure with hydrophobicity.