Spinodal decomposition between closely spaced plates

Abstract

We have studied the dynamics of phase separation in a binary liquid mixture contained between a pair of closely spaced quartz plates. The system behaves very differently from a bulk mixture undergoing spinodal decomposition. For example, the domains do not increase in size as a power of time, and in fact coarsening happens much faster than within a bulk mixture. This is because the process is dominated by the wetting of the plates by one of the two phases. One of the emerging phases, the one that wets the plates, forms an initially thick wetting layer on each quartz plate. Both layers are connected with a few isolated channels. As the time progresses, these layers thin, causing the channel radii to increase. We studied the growth of the channels in detail and found that there was a smallest radius ${\mathit{r}}_{\mathrm{min}}$, such that channels with radius r${\mathit{r}}_{\mathrm{min}}$ dissolved, while those with r>${\mathit{r}}_{\mathrm{min}}$ grew.