Interaction forces between OH-groups in different solvents as observed by scanning force microscopy

Interactions between hydroxyl-terminated surfaces were measured on local scale by performing force-displacement measurements using a scanning force microscope (SFM). For this purpose a SFM-tip was modified by self assembly techniques employing alkanethiolates ω-substituted with OH-groups. Gold surfaces were functionalized employing the same method. Interaction forces between the OH-terminated tip and samples terminated by OH- or CH3-groups were examined in hexadecane and deionized water. As in water OH/OH-interaction forces have been found to be relatively small, in hexadecane larger forces clearly could be detected. Further investigations by a systematic variation of the solvents have been carried out to clarify the origin of the observed strong adhesion forces between OH-groups in unpolar solvents.