Electro-responsively reversible transition of polythiophene films from superhydrophobicity to superhydrophilicity.

An electro-responsively reversible switching of wettability between superhydrophobicity and superhydrophilicity has been obtained from a highly porous structured polythiophene film. The polythiophene film was prepared by two-step electrochemical deposition on an indium tin oxide (ITO) substrate. The underlying poly(3,4-ethylenedioxythiophene) (PEDOT) provides a highly porous structured conductive support, and poly(3-methylthiophene) (P(3-MTH)) deposited thereon plays the role of a low-surface-energy conductive coating. The wettability switching of this double-layer film between superhydrophobicity and superhydrophilicity has been investigated by doping and dedoping in an electrolyte solution containing ClO4(-). Electrochromism of the film was also seen to accompany the electrochemical process of conversion between the two superwetting states. On the basis of this porous electro-active film, an in situ electro-wetting device was also demonstrated.