CONFORMATION OF POLYSTYRENE ADSORBED FROM CYCLOHEXANE ONTO MICA

A spin-labeling technique has been used to study the conformation and mobility of polystyrene (PS) adsorbed onto mica from cyclohexane at 40 °C, and the results have been compared with those from the force-balance method. The effects of surface coverage, diluent, and temperature on polymer-surface interaction were investigated. For example, at saturation coverage more than 80% of the polymer segments were found to undergo fast motion, i.e., be in loops and tails, in the presence of the poor solvent, cyclohexane; the percentage decreased at low surface coverage. This is in contrast to poly (methyl methacrylate) (PMMA), which, after adsorption onto mica, did not show any fast motion in contact with the same solvent. Furthermore, when samples dried with saturation coverage were heated, PS on mica desorbed at a lower temperature than PS on silica. In addition, a significant amount of PS desorbs from mica into pure cyclohexane and even more into benzene, although desorption is a kinetically unfavorable process inthe presence of neat solvents. Our results are consistent with those of the force-balance method, where it was found that PS interacts weakly with mica. © 1990, American Chemical Society. All rights reserved.