As you may know, wettability is a characteristic of each surface which determines what the contact angle would be when a droplet is put on the surface (see here for more info). Surface roughness has a significant effect on wettability. For instance, if you increase the roughness of a polymer surface, the contact angle will be increased as well (i.e. it becomes more hydrophobic).
I need to create a surface such that I can control its wettability by an external stimulus (e.g. temperature, etc.). For instance, a polymer (or any other material) in which when I change its temperature, the surface roughness is also changed (due to change in the molecules chains shape or crystallization). I need to know which materials I can use to create this kind of surface.