Elastic and adhesive properties of alkanethiol (CH3(CH2)n 1SH) self-assembled monolayers on gold are investigated by atomic force microscopy and correlated with surface structure via near edge x-ray absorption fine structure spectroscopy. As the chain length n decreases from 18 to 5, the elastic modulus of the monolayer film, Ef, decreases from 1.0 GPa to 0.15 GPa and the work of adhesion, w, increases from 82.8 mJ m−2 to 168.3 mJ m−2. The Ef and w trends are interpreted in terms of the dichroic ratios, RI, which reveal distinct changes in chain orientation, order, and coverage over the range of n.
Citation: Applied Physics Letters
Pub Type: Journals
atomic force microscopy, mechanical properties, self-assembled monolayers