| Abstract
| - Contact angle measurements have been widely used to estimate the surface energy of various materials.Such measurements are severely limited with substrate surfaces that exhibit surface restructuring, arecontaminated, and/or are porous. Although the captive bubble/drop method addresses the capillarity problem,surface undulations have not previously been accounted for in a quantitative way. We do so here with aseries of 8 different pore size synthetic polymer membranes, all fabricated from poly(ether sulfone), asmodel rough porous surfaces of the same surface chemistry. Also, 3 of the 8 different pore size membraneswere rendered hydrophilic through photoinduced graft polymerization producing 17 different modifiedmembranes that are similarly tested. By incorporation of roughness parameters obtained from AFMmeasurements, corrections to the captive bubble/drop constant angle measurements were successfullymade using a simple model of the surface. The predicted average value for the sessile drop contact angleof poly(ether sulfone) accounting for undulations (44.5 ± 1.3°) was, within error, equal to that valueestimated for a smooth relatively nonporous PES nanofiltration membrane (42.9 ± 2.5°).
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