Investigation and Retardation of the Dewetting on Top of Highly Viscous Amorphous Substrates

Abstract

The dewetting behavior of thin polystyrene (PS) films on top of an amorphous polyamide (PA) layer is investigated at two different annealing temperatures (119 and 195 °C). While PS is liquid at both temperatures, the PA layer remains solid at 119 °C and becomes highly viscous at 195 °C. At a constant thickness of the PA layer, the thickness and the molecular weight of the PS top layer were varied. With optical microscopy and optical phase interference microscopy ex situ the hole growth was measured during the dewetting of the PS layer. A statistical analysis of the data shows evidence for a change in the dewetting mechanism from a spinodal process into a nucleation and growth process as a function of film thickness. For very thin films the effect of a geometrical constraint is discussed. The retardation of the observed dewetting process was achieved by adding a styrene maleic anhydride random copolymer (SMA). The influence of the amount of SMA added and its molecular weight are shown for each given temper...