Towards the determination of surface energy at the nanoscale: a further assessment of the AFM-based approach

Towards the validation of the atomic force microscopy-based approach to the determination of surface energy at the nanometer scale, this paper explores the applicability of the technique by comparing atomic force microscopy-derived surface energy values with those from conventional contact angle measurements from a range of self-assembled organosilane structures ((3-aminopropyl)triethoxysilane, (3-glycidoxypropyl)trimethoxysilane, 3-(triethoxysilyl)propylsuccinic anhydride and trimethoxy(propyl)silane) and also from films of an ultra-low-surface-energy polymer, poly(1H,1H,2H,2H-perfluorodecyl methacrylate). The close agreement between the two sets of data indicates the validity of the AFM method, while unique attributes are indicated by the high resolution (ca. 1000 atoms) that is inherent to the approach and by the capability to study materials that are not compatible with the probing liquids used for goniometric determinations.