| 초록 |
Wrinkle formation in layered bulk systems is a well known phenomenon. Up to now, however, the wrinkle formation is believed to take place spontaneously by the abrupt compressive stress and not much is known about the dynamics. Here we report full-scale evolution of the wrinkle pattern that is driven by an instability, which is initiated by thermal stress in a thin bilayer film of an elastic metal on a viscoelastic polymer. Although the origin is different, transition of an initial island-like pattern to a labyrinthine structure without any change in wavelength (q ~ t_0) and the overall evolutionary process are strikingly similar to those in the spinodal system but the process is robust and takes place on a long time scale (about 10 days). The change into mountainous topography in late stage is accompanied by an increase in length scale from an initial wavelength to another. This change due to relaxation of the confined polymer that results in a transition from elastic- to viscous-like behavior induces wave coarsening (q ~ t_-1.04 ± 0.08) and macroscopic roughening. |
