Electrowetting-Induced Morphological Evolution of Metal-Organic Inverse Opals toward a Water-Lithography Approach

This paper presents a unique morphological evolution of metal-organic inverse opals (Pb(NO3)(2)-poly(St-MMA-AA)) subjected to an electrowetting process. The morphology of the building blocks changes from interconnected pores to separated hollow spheres during the electrowetting process, accompanied by an unusual blue-shift of the stopband position and the decreased wettability of the film. This morphology evolution is attributed to the simultaneous collapse/reconstruction of the metal-organic frame owing to the partial dissolution of the metal salt and the interfacial assembly of the metal-organic coordination around the skeleton. The adjustable morphology can be developed as a novel and simple water-lithography approach for the creation of the photonic crystal pattern.