Viscoelastic thin polymer films under transient residual stresses: two-stage dewetting on soft substrates.

A nonmonotonic, two-stage dewetting behavior was observed for spin coated thin viscoelastic polymer films on soft elastic substrates. At times shorter than the relaxation time of the polymer (t>tau_{rep}), dewetting accelerated, accompanied by an unstable rim. However, holes nucleated at t

Molecular recoiling in polymer thin film dewetting.

The molecular recoiling force stemming from nonequilibrium chain conformation was found to play a very important role in the dewetting stability of polymer thin films. Correct measurements and inclusion of this molecular force into thermodynamic consideration are crucial for analyzing dewetting phenomena and nanoscale polymer chain physics. This force was measured using a simple method based on contour relaxation at the incipient dewetting holes. The recoiling stress was found to increase dramatically with molecular weight and decreasing film thickness. The corresponding forces were calculated to be in the range from 9.0 to 28.2 mN/m, too large to be neglected when compared to the dispersive forces (approximately 10 mN/m) commonly operative in thin polymer films.