Observing wetting behaviors of UV-curable liquid on nanostructured surfaces with sub-20 nm resolution

Abstract

In this work, the liquid acrylated materials were transferred onto the nanostructured surfaces by a transfer printing method. Further, they were frozen (solidified) by UV-light exposure. The morphology of the solidified liquid reflects the original liquid-state profile because the UV-curing shrinkage of the acrylated material was only a few percent in volume so that it would not largely alter the liquid morphology. The cured samples were then examined with high resolution SEM or AFM measurement. This proposed method allows for the observation of liquid behavior down to sub-20 nm scale with more subtle details such as nano-menisci between nanogrooves, and liquid bridges covering nanostructures. The wetting behavior of the liquid strongly depends on the surface properties and geometries of the underlying nanostructures. Experimental results agree with the prediction of a simple surface energy variation model. They indicate that macroscopic wetting behaviors of liquids are preserved as dimensions go down to 100 nm.