Kinetics of polymer adsorption measured in situ at the solid-liquid interface: Utility of the infrared total internal reflection method

The method of infrared spectroscopy in attenuated total reflection (IR-ATR) has been used to study kinetics of polymethylmethacrylate (PMMA) adsorption from dilute carbon tetrachloride solution onto a germanium prism at 27.0°C. By using a combination of deuterated and protio PMMA, it was possible to monitor the initial buildup of the adsorbed layer of one polymer species, followed by the time-dependent displacement of this species when the ambient polymer solution was changed. Data are presented for the displacement of adsorbed deuterated polymer of molar mass 57,000 g by protio polymer of molar mass 400,000 g, and for the displacement of adsorbed protio polymer of molar mass 64,000 by deuterated polymer of molar mass 57,000 g. Although it was not possible to repeat experiments quantitatively, the qualitative conclusion is that in both situations PMMA of molecular weight ca 60,000 g mol^-1 displayed a residence time on the germanium surface of at least several hours. It was possible by this method to measure the kinetic exchange that underlay an overall equilibrium amount of polymer adsorbed.