Computational studies of submicron probing of polymer surfaces. I

The atomistic details of the interaction of an atomic force microscopic (AFM) probe with a polymer surface are examined by using the molecular-dynamics method. It is found that the perturbation of the AFM probe can produce a deformation of the local structure of the polymer surface. The dynamics study reveals how the structural changes evolve during the surface probing experiment, and whether the deformations result in permanent or reversible structural damage upon removing the probe. The effects of probe features (radius of curvature) and load force on the surface deformation(s) and image resolution are investigated in both a constant-force and constant-height AFM mode. Load forces between 10^-8 and 10^-11 N were determined to be an optimum working range for nondestructive AFM probing of polymer surfaces, and consequently for well-resolved surface image production.