Micro and nanowrinkled conductive polymer surfaces on shape-memory polymer substrates: Tuning of surface microfeatures towards smart biointerfaces

With the aim of providing an easy and versatile method for realizing conductive polymer surfaces with controlled micro and nano-scale topographical cues patterning, we deposited a ultra-thin film of the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on a thermo-retractable polystyrene sheet. Biaxial and uniaxial micro and nano-wrinkles were formed with different features depending on clamping geometry during shrinking of the substrate upon heating. Homogeneous nano and micro-patterning of surface topography over large areas (several cm²) was obtained. The formed wrinkles were very robust and adhered strongly to the substrate because of their penetration into the soft substrate during the heat-shrink process. In the case of uniaxial wrinkles a very well aligned quasi-periodic structure is formed with different populations of wavelengths ranging from submicrometric to 10-20 μm, depending on PEDOT:PSS thickness. Surface topography, wrinkles amplitude and wavelength have been evaluated by means of SEM and AFM and the results have been related to sheet resistance as measured with a four point probe technique. The realized conductive surfaces can offer new opportunities in the field of cell stimulation and growth.