Wetting of TX-100 and Igepal CO-630 Surfactants on a PTFE Surface

Abstract

Nonionic surfactants are advantageous in a diversified range of applications from household cleaners, laundry detergents, and shampoo to paints, coatings, and food emulsifiers because of their low CMC and surface tension values over the ionic surfactants. Nonionic surfactants, in general, are very useful in mixed surfactant systems because of their electrical neutrality. Among the similar class of nonionic surfactants, structural difference is important in the performance. In this study, we report on the adsorption and wetting behavior of two nonionic surfactants (TX-100 and Igepal CO-630) having the same head group but structurally different tail groups. The kinetics of adsorption follows a pseudo-second-order kinetic model and a Langmuir-type isotherm for both the surfactants. The change in contact angle with the concentration of surfactant follows a trend similar to that for adsorption onto a PTFE surface. At low surfactant concentration, Igepal CO-630 shows a slightly higher adsorption density and better wetting properties than TX-100. Both surfactants show lower adsorption densities at the PTFE–water interface than at the air–water interface.