Morphology of polymer-polymer dewetting in thin films

Abstract

Two or more thin polymer layers are frequently combined for industrial applications such as protective coatings, lubricants, packaging, and adhesives. One might refer to such multi-layered polymeric structures as planar nanocomposites. The use of multiple polymer thin films requires the control of spreading and dewetting of these films. Our studies have identified a number of important characteristics of the kinetics and morphology of polymer melt / polymer melt dewetting. Particularly noteworthy is our ability to distinguish the two polymer melts in a cross-sectional view. At 190°C a 200 nm film of polycarbonate (PC) was found to dewet a 200 nm film of poly(styrene-co-acrylonitrile) (SAN) which had been deposited onto a rigid substrate. An optical micrograph of an intermediate stage of polymer-polymer dewetting shows the characteristic features: a circular hole in the upper layer (light gray), a rim surrounding the hole, and a small dimple in the center of the hole (dark gray), Figure 1.