Influence of Molecular Arrangement in Self‐Assembled Monolayers on Adhesion Forces Measured by Chemical Force Microscopy

Nanopatterned self-assembled monolayers

“…This observation indicates that the alkylbased nanofeatures interact more strongly with the AFM tip than the OH-ended background, which may only be the case if the SAMs in the nanofeatures are of sufficiently high disorder to allow for a higher dissipation of mechanical energy. Indeed, a direct consequence of lower packing density is that a higher friction develops between the tip and the surface [24,25], as explained above. This observation is in agreement with our previous conclusion that SAM layers grown in the nanoholes of the PMMA mask are of limited quality.…”

“…Decreased packing may originate from molecular pits or from a low grafting density, resulting in gauche defects or other conformational distortions of the chains which partially collapse on the substrate. This results in a lower layer thickness and also in higher friction in the LFM, due to the increased number of available vibrational and relaxation modes under contact, which increases energy dissipation [24,25]. It is well known that high temperatures or even simple immersion in various solvents may lead to desorption of thiols [19,33].…”

Plasma functionalization of AFM tips for measurement of chemical interactions

“…In atomic force microscopy derivatives such probe modifications were extensively used to identify and quantify chemical and biological interactions [17]. For example, chemical force microscopy reveals specific chemical functionality at the nanoscale by using chemically modified AFM probes [18]. In such a case, hydrogen-bonding and/or hydrophobic interactions are governing the probe-surface interaction, providing chemical contrast in the resulting SPM images.…”

Chemical force microscopy: probing chemical origin interfacial forces and adhesion

“…The degree of packing in the SAM is affected by the anchoring mechanism and defect density and is different in thiolates on Au, trichrolosilanes on Si, and trimethoxysilanes on Si. [73].…”