Drying Enhanced Adhesion of Polythiophene Nanotubule Arrays on Smooth Surfaces

Polythiophene (Pth) films with aligned nanotubule arrays were adhered strongly on various smooth surfaces such as glass, mica, and GaAs after drying from their wet states under ambient condition. The normal and shear dry adhesion forces of the films on glass with contact areas of 0.5-1.0 cm(2) were measured to be 80 +/- 8 and 174 +/- 10 N cm(-2), respectively. These extraordinary strong adhesion forces are attributed to the high strength and stiffness of Pth and the high contact fraction (similar to 79%) of Pth nanotips on the smooth surfaces induced by drying. During the drying process, there is little controlled preload, suggesting a real gecko-like adhesion of Pth nanotubule arrays.