There is a long time controversy on whether unstable polymer liquid films break up via spinodal destability or nucleation and growth when the bicontinuous morphology cannot be found in the dewetting of the film. By applying the artificial induced topographical defects, we are able to unambiguously distinguish the dominating dewetting mechanisms, and find that as the thickness increases there is a critical thickness across which the dominating dewetting mechanism changes from the spinodal to the nucleation. Our further study shows that the occurrence of the critical thickness can only be due to the kinetic crossover resulting from the competition between those two major dewetting mechanisms. Time evolution study is carried out on the development of the dewetting morphology on the sample...[ Read more ]

There is a long time controversy on whether unstable polymer liquid films break up via spinodal destability or nucleation and growth when the bicontinuous morphology cannot be found in the dewetting of the film. By applying the artificial induced topographical defects, we are able to unambiguously distinguish the dominating dewetting mechanisms, and find that as the thickness increases there is a critical thickness across which the dominating dewetting mechanism changes from the spinodal to the nucleation. Our further study shows that the occurrence of the critical thickness can only be due to the kinetic crossover resulting from the competition between those two major dewetting mechanisms. Time evolution study is carried out on the development of the dewetting morphology on the sample with the thickness within the spinodal dominating regime. It shows that the dispersion relation of the growth rate is consistent with the theoretical description based on the mean-field theory if corrections due to the non-linear effects and stochastic thermal fluctuations are considered. Analyzing the energy cost to create a hole reveals the existence of the thermal nucleation.