ABSTRACT
Another A F M application is the mapping of the chemical composition of a surface by high-resolution adhesion measurements [6, 104-108]. In our group Schonherr et al. recently investigated the spatial distribution of ionizable functional groups in surface treated polymers with chemically modified tips ('chemical force microscopy') [108]. Silicon nitride tips were coated with Ti and Au in high vacuum and functionalized with 11-hydroxyundecanol and used to probe oxyfluorinated polypropylene films in solution as a function of pH. The study of the distribution of pull-off forces revealed the sub-50 nm variation in chemical composition. In addition, the influence of roughness on adhesion of chemically treated polyethylene was studied. It was found that roughness introduced by using chromic acid treatment reversed the trends in pull-off forces, which was anticipated due to the introduction of polar groups at the polymer surface during the treatment [109].
