Nanotribology of Spiderman

Invited lecture, Int. Conf. Nanoscience & Nanotechnology, Frascati (ITA), Nov. 6-9, 2006. --- Spiders can produce cobwebs with high strength to density ratio and surprisingly display self-cleaning, strong and releasable adhesion (as geckos). Nanointerlocking, capillary and van der Waals forces, all potential adhesive mechanisms, were thus discussed, demonstrating the key role played by hierarchy to the design of super-hydrophobic, i.e. self-cleaning (by activating fakir drops as in lotus’ leaves) and super-adhesive materials. The reversibility of the strong attachment was quantified thanks to an improved nonlinear peeling model, for which the solution in closed form was provided. Thus, mimicking Nature, thanks to carbon nanotube-based technology, we have suggested [N. Pugno, J. Phys. Condens. Matter 19, 395001 (2007)] the feasibility of large invisible cables, as well as of self-cleaning, super-adhesive and releasable hierarchical smart materials. We have found that a man can be supported by a transparent cable with cross-section of 1 cm2 and feasibly, with spider material gloves and boots, could remain attached even to a ceiling: a preliminary step towards a Spiderman suit.