|
Physical Society Colloquium
Hole Formation, Pattern formation and the Glass Transition Dr. K. Dalnoki-Veress
Department of Physics and Astronomy Various aspects of confinement effects on thin polymer films will be presented starting with thermal instabilities which lead to hole formation in thin free-standing films (membranes). To increase the thermal stability the free-standing films were symmetrically confined by thin, solid layers to form trilayer films. Aggressive annealing of this lamellar structure produces a novel lateral morphology which is driven by the attractive dispersion force. This lateral morphology is discussed in terms of a simple model. The dynamics of thin polymer films is also affected by confinement resulting in large reductions in the glass transition temperature as the thickness of free- standing films is decreased. We present data on the reduced glass transitions observed in thin free-standing films. The data is highly suggestive of a mechanism of mobility in thin free-standing films that is inhibited in the bulk and distinct from the usual motion near the glass transition temperature. A tentative mechanism for the glass transition temperature reductions is discussed.
>Thursday, February 3rd 2000, 15:30 |