Synergism of Self-Wrinkling and Ultrasonic Cleaning to Fabricate Hierarchically Patterned Conducting Films

Patterning functional materials into well-defined microstructures has drawn increasing attention in material science, bioengineering, surface engineering, nanotechnology, and especially in device processing. Here, a simple versatile route is developed to fabricate hierarchical surface patterns on conducting polymer films in solution via a combination of surface wrinkling and ultrasonic cleaning. Heterogeneous surface architectures (e.g., wrinkles/delaminating buckles) are first obtained owing to in situ self-wrinkling during the solution-phase growth of polyaniline (PANI) film on a selectively oxygen plasma-exposed polydimethylsiloxane (PDMS) substrate. Subsequent ultrasonic cleaning is introduced to selectively remove the patterned PANI film that is deposited in the exposed PDMS region, based on the different adhesion strength of the patterned film with the exposed and unexposed PDMS regions. As a result, corresponding hierarchically patterned PANI films with controlled microstructures, spatial locations, and dimensions are obtained. Combined with the additional self-reinforcement effect by polymerization of polymerizable monomers into the patterned PANI film, well-defined stabilized patterns of PANI-based composite films are further fabricated, which have great potential for the applications in micro-supercapacitors and integrated pressure sensor arrays with excellent performances, as demonstrated here.