Effect of altered surface substrate chemistry on critical adsorption from a binary liquid mixture.

Abstract

We have demonstrated the importance of the surface chemical character of the substrate in the phenomenon of critical adsorption---the long-range perturbation of chemical concentration in a critical binary liquid mixture by a boundary. By measuring the reflectivity of the solid/liquid interface between borosilicate glass and a mixture of carbon disulfide and nitromethane near its critical demixing point, we find that the substitution of methyl for hydroxyl groups on the glass surface inverts the sign of the long-range order-parameter perturbation.