Fluid transport in open-cell polymeric foams: effect of morphology and surface wettability

Abstract

Fluid transport behavior inside polymer foams (polyHIPEs) templated from high-internal-phase emulsions (HIPEs) has been studied. Morphological properties of the foams were controlled through shearing their precursor emulsions for varying durations. Two types of flow, Darcy flow through the filled foam, and capillary imbibition into unfilled foams, have been studied. From permeability measurement, the size of the interconnections (windows) between the voids of the polyHIPE was found to provide the appropriate characteristic length to describe Darcy flow. For capillary imbibition, liquid/foam interaction effects were studied under two wetting conditions: silicone oil in which the oil readily spreads (at a vanishing contact angle) on the struts within the foam; and, using water and foams coated with various amount of surfactant where the liquid only partially wets the surface. For capillary imbibition, the dominant morphological feature was also the window size when the internal surfaces of the foam have a macroscopically uniform wettability for the liquid. The Lucas–Washburn analysis was found to well describe imbibition rates in this case. However, when the internal surfaces of the foam have a non-uniform wettability (due to a non-uniform deposition of surfactants), the concentration and distribution of surfactants plays a large role in determining imbibition kinetics.