Adhesion is the science of stickiness. Everyday life examples where adhesion is important are tape, glue and velcro, a more exotic example from biology is the gecko that can walk on the ceiling. The physical origins behind adhesion range from polymer entanglement (tape), to chemical bond formation (glue), mechanical interlocking (velcro) or Van der Waals interactions (Gecko). This case of the gecko shows the extreme importance of the surface structure for adhesion: gecko have nanometric pillars on their feet and with these pillars they can create very intimate contact even with rough surfaces, allowing them to utilize weak Van der Waals interactions to stick to the ceiling.
Recent research in our group includes unravelling the mechanisms behind DIY Gecko tape [1], and the unrolling of Scotch tape [2]. Future work can be expected on the interrelation of friction and adhesion, with special attention to adhesive transfer film formation in Teflon.
Contact:
Hans Terwisscha-Dekker (h.dekker2@uva.nl)
Marion Grzelka (m.grzelka@uva.nl)
References:
Terwisscha-Dekker et al., “How does ”Gecko tape” work?’, Biotribology, 2021, https://doi.org/10.1016/j.biotri.2021.100179
Grzelka et al. Transition from viscoelastic to fracture-like peeling of pressure-sensitive adhesives, Soft Matter, 2022, https://doi.org/10.1039/D1SM01270C