Facile fabrication of stable wettability gradients on elastomeric surfaces for applications in water collection and controlled cell adhesion.

We have developed a simple and effective method to prepare stable wettability gradients on an elastomeric soft substrate, polydimethylsiloxane (PDMS). In our method, a partially cured PDMS film composed of a definite ratio of elastomer and crosslinking agent was heated over a hot surface with a temperature gradient. This causes differential thermal curing of the PDMS film and the water contact angle (wettability) of the resultant surface showed gradual variation across the length.