The adsorption and desorption of polystyrene (PS) from cyclohexane at 34.8 °C (θ temperature) on a chrome mirror has been studied by using ellipsometry. Static adsorption measurements give adsorbed layer thickness and adsorbed amounts in agreement with previous investigators. The effect of elongational flow on polymer adsorption and desorption was studied by directing a jet of polymer solution or solvent perpendicular to the mirror surface, to produce an elongational velocity field at the stagnation point on the surface. For a 107 MwPS adsorbed under strong elongational flow conditions, the adsorbed layer was an order of magnitude thinner than a layer adsorbed under quiescent conditions and the polymer concentration in the layer adsorbed under elongational flow was 3.4 times higher. The effect of elongational flow of solvent on the desorption of a polymer layer formed under quiescent conditions was studied. No desorption was observed at the stagnation point. The impinging solvent jet produced a distinctive pattern on the chrome mirror in the desorption experiments. A “bull's-eye” pattern was visible on the dried mirror, showing a center circle of adsorbed polymer, a clear annular ring where shear forces desorbed the polymer, and a region of adsorbed polymer out beyond the desorbed ring.
All Science Journal Classification (ASJC) codes
- Organic Chemistry
- Polymers and Plastics
- Inorganic Chemistry
- Materials Chemistry