Melt fracture in polymer thin films at strongly attractive surfaces

Ultra-thin film lubricants with nanoscale control of surface morphology are becoming increasingly important due to the recent push for miniaturization of electromechanical devices. In this letter, we report on an interesting phenomenon dubbed "melt fracture" when a high-viscosity film was allowed to dewet from a film of lower viscosity. We attribute this phenomenon to the shearing at polymer/polymer interface and pinning at the polymer/Si interface. Melt fracture occurs when the shear rate is faster than the natural reptation time of polymer chains. We show that the degree of melt fracture is a function of annealing time and polymer molecular weight. Furthermore, we demonstrate that screening of the substrate interactions, allowing the film to slip can reduce the degree of melt fracture.