Dispersion-Driven Morphology Manuscript

DISPERSION-DRIVEN MORPHOLOGY OF MECHANICALLY-CONFINED POLYMER FILMS

Kari Dalnoki-Veress, Bernie G. Nickel and John Dutcher,
Phys. Rev. Lett. 82, 1486-1489 (1999).

ABSTRACT

For temperatures greater than the glass transition temperature, thin freely-standing polymer films are unstable to the formation of holes. To increase the thermal stability of freely-standing polystyrene (PS) films and probe the effects of mechanical confinement, we have symmetrically capped freely-standing PS films by thin, solid layers to form trilayer films. Aggressive annealing of the trilayer films produces a novel lateral morphology, consisting of long, parallel domains with a well-defined periodicity, which is driven by the attractive dispersion force between the two capping layers. A simple model is presented which describes the scaling behavior of the morphology with the individual layer thicknesses. Observation of the same morphology for eight different systems, both freely-standing and supported films, illustrates the general nature of the morphology. In one case, we demonstrate reversibility of the morphology by manipulation of the dispersion force.