Adsorption and desorption rates of polystyrene on flat surfaces

Abstract

The rates of adsorption and desorption of polystyrene have been measured in cyclohexane and benzene solutions by radiotracer techniques. Relatively long times were required to attain maximum adsorbance values for adsorption of both low and high molecular weight polymer on a solid chrome surface under theta conditions. This was interpreted as indicating a molecular reorientation during the adsorption process. Under these conditions it was observed that the maximum adsorbance values increased with increasing molecular weight, but the amounts adsorbed were independent of molecular weight at very short adsorbance times. This was interpreted as indicating two separate rates of adsorption : an initial rate dependent on the rate of arrival and attachment at the surface and the rate of re-arrangement on the surface. More rapid attainment of maximum adsorbance values on a mercury surface was attributed to participation of the liquid mercury surface in accommodating the changing polymer conformation. The rates of desorption were very slow for both chrome and mercury and were dependent on the surface populations as determined by the adsorbance values.