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CPM Seminar
From Pattern Formation to Rupture John R. Dutcher
Department of Physics Thermal fluctuations of the interfaces of thin polymer films are amplified by the long-range, attractive van der Waals or dispersion force. In freely-standing polymer films heated above the glass transition temperature, this instability leads to the formation of holes. We have measured the formation and growth of holes in very thin, freely-standing polystyrene (PS) films to learn about the mobility of the confined polymer molecules. We have also symmetrically capped freely-standing PS films with thin, solid layers to probe the effects of mechanical confinement. Aggressive annealing of the trilayer films produces a novel in-plane morphology which can be understood in terms of the balance between the decrease in free energy associated with the dispersion interaction and the increase in free energy associated with the bending of the capping layers. The general nature of the morphology, and its reversibility, will be demonstrated.
Wednesday, January 20th 1999, 15:30 |