Spinodal Decomposition-Induced Surface Wettability Modification of Thermo-Responsive Nanoemulsion Films

Functional polymer thin films with a multilayer structure have been constructed with nanometer scales typically by using the sequential adsorption of oppositely charged polyelectrolytes onto a solid substrate. Tight control over phase separation is essential for providing the film with structured surface heterogeneity as well as surface functionality. Herein, we fabricate nanoscale emulsion thin films by utilizing the layer-by-layer deposition. Their thickness was tunable to micrometer scales by solely changing the number of alternate emulsions and polyelectrolytes layers. Interestingly, the nanoemulsion films exhibited a thermos-responsive heterogeneous phase separation behavior, which is typically referred as Spinodal decomposition. We observed that surface wettability of the Nanoemulsion films was critically dependent upon the pattern of the Spinodal decomposition, which enables development of thin film-based smart drug delivery patches.