Dynamic AFM on Viscoelastic Polymer Samples with Surface Forces

Abstract

Dynamic atomic force microscopy (dAFM) is widely used to characterize polymer viscoelastic surfaces in the air/vacuum environments; however, the link between the instrument observables (such as energy dissipation or phase contrast) and the nanoscale physical properties of the polymer surfaces (such as local viscoelasticity, relaxation, and adhesion) remains poorly understood. To shed light on this topic, we present a computational method that enables the prediction and interpretation of dAFM observables on samples with arbitrary surface forces and linear viscoelastic constitutive properties with a first-principles approach. The approach both accelerates the computational method introduced by Attard and embeds it within the tapping mode amplitude reduction formula (or, equivalently, frequency modulation frequency shift/damping formula) to recover the force history and instrument observables as a function of the set point amplitude or Z distance. The method is validated against other reliable computational ...