Surface modification of polyimide films, filter papers, and cotton clothes by HMDSO/toluene plasma at low pressure and its wettability

This study demonstrates the hydrophobic and super-hydrophobic coating of various substrates by 3:1 HMDSO/toluene glow plasma discharge at low pressure and investigates the hydrophobic and super-hydrophobic behavior of the polyimide films, filter papers, and cotton clothes. The effect of 3:1 HMDSO/toluene plasma treatments on the surface of polyimide films, filter papers, and cotton clothes were investigated in terms of total surface free energy by measuring the contact angles with probe liquids. In representation, the total surface free energies of the polyimide films before and after the 3:1 HMDSO/toluene plasma modification estimated from the Owens–Wendt equation decreased from 44.5 mN/m to 13.94 mN/m, showing the significant improvement of hydrophobicity of all sample surfaces treated by 3:1 HMDSO/toluene plasma.