Honisch Christoph, Lin Te-Sheng, Heuer Andreas, Thiele Uwe, Gurevich Svetlana V
Institute for Theoretical Physics, University of Münster , Wilhelm-Klemm-Str. 9, 48149 Münster, Germany.
Department of Applied Mathematics, National Chiao Tung University, Hsinchu , 30010 Taiwan.
Langmuir. 2015 Sep 29;31(38):10618-31. doi: 10.1021/acs.langmuir.5b02407. Epub 2015 Sep 17.
A mesoscopic continuum model is employed to analyze the transport mechanisms and structure formation during the redistribution stage of deposition experiments where organic molecules are deposited on a solid substrate with periodic stripe-like wettability patterns. Transversally invariant ridges located on the more wettable stripes are identified as very important transient states and their linear stability is analyzed accompanied by direct numerical simulations of the fully nonlinear evolution equation for two-dimensional substrates. It is found that there exist two different instability modes that lead to different nonlinear evolutions that result (i) at large ridge volume in the formation of bulges that spill from the more wettable stripes onto the less wettable bare substrate and (ii) at small ridge volume in the formation of small droplets located on the more wettable stripes. In addition, the influence of different transport mechanisms during redistribution is investigated focusing on the cases of convective transport with no-slip at the substrate, transport via diffusion in the film bulk and via diffusion at the film surface. In particular, it is shown that the transport process does neither influence the linear stability thresholds nor the sequence of morphologies observed in the time simulation, but only the ratio of the time scales of the different process phases.
