Control of the surface wetting properties of polymer and metal oxides using charged particle irradiation

Abstract

This study investigated the effects of charged particle beam irradiation on the surface wettability of polymer and metal oxide materials. He ions were utilized as the charged particles and irradiated onto the hydrophobic surfaces of polystyrene and high-density polyethylene, as well as the hydrophilic surface of alumina, under high-energy conditions. Irradiated materials exhibited enhanced chemical reactivity, accompanied by surface oxidation. Interestingly, although no significant changes in surface morphology were observed for both the polymer and metal oxide surfaces, there was a notable modification in the chemical structure of the surfaces. On the polymer surface, as the fluence of beam irradiation increased, the contact angle tended to decrease, indicating a weakening of hydrophobicity. Moreover, the nitrogen species generated by high-energy ion beam irradiation formed amide bonds on the surface. In the case of alumina, an increase in beam fluence resulted in an elevated number of oxygen vacancies on the surface, diminishing the inherent hydrophilicity of the metal oxide. Additionally, fluorine species formed under high-energy conditions, contributing to the formation of robust hydrophobic functional groups on the surface.