title: Tunable Friction Behavior of Photochromic Fibrillar Surfaces.
abstract: Grasslike compliant micro/nano crystals made of diarylethene (DAE) photochromic molecules are spontaneously formed on elastomer films after dipping them in a solution containing the photochromic molecules. The frictional forces of such micro- and nanofibrillar surfaces are reversibly tuned upon ultraviolet (UV) irradiation and dark storage cycles. This behavior is attributed to the Young's modulus variation of the single fibrils due to the photoisomerization process of the DAE molecules, as measured by advanced atomic force microscopy (AFM) techniques. In fact, a significant yet reversible decrease of the stiffness of the outer part of the fibrils in response to the UV light irradiation is demonstrated. The modification of the molecular structure of the fibrils influences their mechanical properties and affects the frictional behavior of the overall fibrillar surfaces. These findings provide the possibility to develop a system that controllably and accurately generates both low and high friction forces.
authors.affiliation: †Smart Materials, Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy.|‡Dipartimento di Fisica, Università degli Studi di Genova, via Dodecaneso 33, 16146 Genova, Italy.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Nanni
authors.affiliation: †Smart Materials, Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Ceseracciu
authors.affiliation: §Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy.|⊥DIBRIS Department, University of Genova, viale Causa 13, 16145, Genova, Italy.
authors.forename: Reinier
authors.initials: R
authors.lastname: Oropesa-Nuñez
authors.affiliation: §Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Canale
authors.affiliation: †Smart Materials, Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy.
authors.forename: Princia
authors.initials: P
authors.lastname: Salvatore
authors.affiliation: †Smart Materials, Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy.
authors.forename: Despina
authors.initials: D
authors.lastname: Fragouli
authors.affiliation: †Smart Materials, Nanophysics, Istituto Italiano di Tecnologia, via Morego 30, 16163 Genova, Italy.
authors.forename: Athanassia
authors.initials: A
authors.lastname: Athanassiou
mesh_terms: D005030:Ethylenes / Q000737:chemistry*; D017276:Friction; D018625:Microscopy, Atomic Force; D010316:Particle Size; D055668:Photochemical Processes; D013499:Surface Properties; D014466:Ultraviolet Rays
chemical_list: D005030:Ethylenes