Dewetting instabilities in thin block copolymer films: Nucleation and growth

We examined the dynamics of dewetting of a thin symmetric diblock copolymer film on a substrate above the bulk order-disorder transition temperature, T-ODT. Of the copolymer using atomic force microscopy. The dewetting mechan ism proceeded with the formation of discrete holes without their characteri stic peripheral rims. During this early stage, the hole radii R increased e xponentially with time. This stage was followed by a narrow intermediate re gime where the rim develops and R similar to t. When the rim was fully deve loped, R increased as t(2/3). The shape of the rim was highly asymmetrical and its width L increased as t(1/2). At the final stage of the process, dro plets of the copolymer, a few microns in diameter and with heights on the o rder of tens of nanometers, existed on a dense copolymer "brush" of uniform thickness 7 nm anchored to the substrate. This clearly indicates that the process is autophobic, a phenomenon first documented in small molecule liqu ids.