Atomic Force Microscopy of Polymer Brushes: Insights into Controversies

Atomic force microscopes (AFM) and nanoindenters have been used for decades to evaluate mechanical properties of thin films at the nanoscale. It is argued that elastic solutions indentation problem, which are most often associated with names Galin or Sneddon, may be extracting contact modulus bulk samples continual films, while their application between an AFM probe a polymer brush priori questionable. This because character compression drastically different from response half-space indentation. In present paper, number controversial issues related interpretation data obtained brushes tested rigid studied. particular, correct relation has established constitutive equation single in bare surface two identical under assumption lack interpenetration compressed brushes. shown so-called apparent introduced based on Hertzian force-displacement depends indenter radius and, thus, not serve as characteristic brush. Also, Derjaguin’s approximation-based method identifying point initial given opposition methods, broadly mechanics.