A direct method of studying polymer adsorption onto mica surfaces using a commercial mettler ultramicrobalance

This paper deals with a simple and direct method of determining absolute va lues of adsorbance, i.e., mass per unit area, of polymers adsorbed from sol ution onto mica surfaces. The method is based on direct weighing of mica sh eets using a Mettler ultramicrobalance UMT2 or UM3 (readability 1 x 10(-4) mg), which is commercially available. A set of mica sheets is weighed twice ; before and after the immersion of mica sheets in polymer solution for a g iven period of time. The difference in weight of the mica sheets gives the mass of adsorbed polymers, which is divided by the total area of mica surfa ce to derive the adsorbance, Measurable change in adsorbance was 0.1 mg m(- 2) in consideration of the size of mica sheets (50 cm(2) in total surface a rea) and the scatter of readings of the ultramicrobalance. A detailed descr iption is given on the apparatus and procedures for weighing and adsorption experiments. The present method has been applied to the experiments on the adsorption kinetics of polystyrene from cyclohexane and of bovine serum al bumin from aqueous solution onto mica surfaces. Some of the experimental re sults are presented to show the practical examples of the application of th is method. (C) Im Academic Press.