Electrostatic properties of mercaptoundecanoic-acid-coated-gold surfaces interacting with TiO₂ surfaces

We studied electrostatic properties of the MUA-coated-gold surface and the TiO₂ surface for design of gold-TiO₂ distribution, which may be controlled with electrostatic interactions. The forces between the surfaces were measured as a function of the salt concentration and pH value using the AFM. By applying the DLVO theory to the forces, the potential and charge density of the surfaces were quantitatively acquired for each salt concentration and each pH value. The potential and charge density dependences on the salt concentrations and the pH values were explained with the law of mass action and the ionizable groups on the surface.