ABSTRACT
Aqueous film stability is dependent on the adhesive force or negative interfacial tension at the two-phase (i.e., solid/liquid) boundary. The force balance at the twophase boundary may change independently from the three-phase force balance due to surface configuration change of interfacing surface state moieties, which occurs in order to minimize interfacial tension with water as described in previous chapters.
The extent of intrinsic hysteresis can be determined by exposing a Wilhelmy plate to two consecutive wetting cycles, each consisting of one immersion step followed by an emersion step, and observing the extent of deviation between the first and second immersion lines. Most low-energy polymeric surfaces exhibit the common, ideal parallelogram-shaped force loops, since the intrinsic hysteresis is usually relatively small or even zero. The deviation between the first and second immersion lines is a result of surface configuration change during the time scale of Wilhelmy force measurement.
