In Situ Self-Reinforcing Surface Self-Wrinkling Polypyrrole Films

Here,a simple versatile method to obtain large-area free-standing polypyrrole(PPy)films with stable hierarchical wrinkles were reported.It is mainly based on in-situ surface wrinkling coupled with the simultaneous self-reinforcing effect.Namely,when PPy film was grown on polydimethylsiloxane(PDMS)substrate via a solution-phase polymerization,the occurrence of the in-situ self-reinforcing surface wrinkling led to unexpected two-scale wavelengths of stabilized wrinkling patterns.The influences of the experimental conditions(e.g.,deposition time,stiffness and surface geometry of PDMS substrate)on the resulting morphologies had been investigated systematically.The morphology of obtained-PPy film was characterized by optical microscopy,Scanning electron microscopy,atomic force microscopy and 3 D laser microscope.When we replaced the initial planar PDMS substrate with a physically-patterned PDMS stamp,the labyrinth patterns on the in-situ PPy film evolved into ordered patterns with the orientation perpendicular to the introduced boundary.As for the surface patterns that were far from the boundary,they still kept the initial disordered orientation.The response of PPy film from different reaction time and on different substrates to different concentration of NH3 was investigated.Interestingly,we took advantage of the enhanced wrinkle stability to successfully construct free-standing PPy films with the intact stable wrinkles for the first time,which were further transferred onto target substrates for functional device fabrication.Additionally,highly hierarchical wrinkles with tunable wetting properties had been generated,when the in-situ two-scale wrinkles were well organized with newly triggered ones by the post-treatment of external stimuli.