Contact angle studies of surface-hydrophilic elastomer films

The surface properties of a film made from a novel latex product, surface-hydrophilic elastomer latex (SHEL), were studied by the sessile-drop contact-angle technique. The advancing contact angle of water on a SHEL film was very low, indicating that the surface was hydrophilic. The surface hydrophilicity was sustained even after being placed in dry air or washed with an excess amount of water for a prolonged period of time. These results suggest that the observed low water contact angle on the SHEL film results from the high surface energy of the solid rather than from simple reduction of the water surface tension. Zisman critical surface tension analysis was carried out by measuring advancing contact angles of inorganic salt solutions having surface tensions higher than that of pure water. The result shows that the SHEL film has a critical surface tension of 62 ± 2 mN/m. Since the surface tension of water is usually brought down below this level by even a slight contamination, in normal practice, this material can be regarded as virtually completely water-wettable.