Use of Attenuated Total Internal Reflection−Fourier Transform Infrared Spectroscopy To Investigate the Adsorption of and Interactions between Charged Latex Particles

The adsorption of 67-, 190-, and 1000-nm-diameter carboxylated latex particles onto hydrophobic and hydrophilic surfaces, from aqueous dispersions of these particles that contain different concentrations of sodium chloride, have been investigated, in situ, by attenuated total internal reflection−Fourier transform infrared spectroscopy. Adsorption of the carboxylated latex particles onto the substrates in a given sample increased exponentially with time and then leveled off to a plateau value ( A exp ). The value of A exp was dependent on the size of the carboxylated latex particles and on the electrolyte concentration in the dispersions. A exp values were used to calculate the maximum coverage of the substrate by the adsorbed carboxylated latex particles (ϑ max values). The ϑ max values decreased as the particle size and the ionic strength of the medium decreased. These results were discussed in terms of the product of the Debye length and the radius of the particles (i.e., in terms of the screening parameter, κ a ).