Macromolecules, Vol.34, No.11, 3741-3747, 2001
Leveling and dewetting processes of nanoindentation-induced defects on thin polymer films
study the effect of nanoindentation-induced indents on polystyrene (PS) films (thickness = h > 100 nm); spin-cast on silicon substrates. Indents with residual depths of penetration, zn, comparable to the film thicknesses leveled (healed) upon heating above the glass transition temperature (T,) of bulk PS, resulting in a flat polymer surface. Deep indents which clearly penetrated the films and damaged the substrate dewetted from the silicon surface. The healing rate, dz(D)/dt, was measured for several molecular weight PS films and found to scale with the curvature of the hole bottom, H-D, as (dz(D)/dt) HD0.52 +/-0.05. Measurements were performed using atomic force microscopy. The healing rate was found to be, in general, higher than the dewetting rate of the laterally expanded deep indents.