Abstract
In general, the relaxation of polymers from a nonequilibrium state will occur only if the polymer is above the bulk glass temperature. To examine the influence of a free surface on the mobility of polymer chains, the free surface of thick, artificially roughened polystyrene (PS) films (> 10 μm) was studied. Each surface asperity of the PS film represents a nonequilibrium system with a large interracial surface area. The Laplace pressure tends to suppress surface roughness, which can only occur if the polymer chains within the asperities are mobile. A partial relaxation of the surface asperities at temperatures well below the bulk glass temperature was observed. With increasing temperature the lateral size of the remaining surface asperities was found to increase, and the aspect ratio of the asperities decreased. However, a complete relaxation of the surface structures occurred only for temperatures comparable to or greater than the bulk glass transition temperature.
| Original language | English |
|---|---|
| Pages (from-to) | 3484-3492 |
| Number of pages | 9 |
| Journal | Macromolecules |
| Volume | 34 |
| Issue number | 10 |
| DOIs | |
| State | Published - 8 May 2001 |