Spreading and Wetting Behaviour of Trisiloxanes

Wetting and spreading processes which involve surfactant solutions are widely used in numerous industrial and practical applications nowadays. The performance of different non-ionic surfactants may vary significantly and so far superspreader solutions show the most promising spreading ability. The addition of trisiloxane surfactants to water was proven to enhance wetting, even on hydrophobic surfaces, on which conventional surfactants seem to have little or no effect. Although these extraordinary surfactants have been extensively studied over recent years, complete understanding of their underlying mechanisms and a suitable mathematical model are still lacking. Here we present a possible explanation for the impressive performance of trisiloxane, which is compared to wetting enhancement of a conventional surfactant. Additionally, we will explain why the hydrophobicity of the surface is a crucial factor for the spreading phenomenon. Light will be also shed on the effect of the pH of the solution to which surfactants are added. Finally, we will investigate long-term effects of the water environment on trisiloxane wetting ability and discuss if ageing may significantly affect their performance.