Latex elastomer with a permanently hydrophilic surface

Abstract

WATER wettability is important in many applications of polymeric materials, including fabrics, printing and biomedical uses^1,2. Various surface-modification techniques are available to convert the intrinsically hydrophobic surfaces of plastic to water-wettable ones, by incorporating chemically polar functional groups at the surface^4–7. Although such chemically induced surface hydrophilicity can be relatively long-lived while the substrates remain rigid, increases in the mobility of surface molecules, for example, due to increasing temperature, can cause rapid loss of hydrophilicity, driven by the tendency of surfaces to minimize their free energy^2–5. As the polar groups are not often bound to the polymer matrix (usually being instead free surfactant molecules), they may also be flushed from the surface by repeated exposure to water. Here I report the preparation of permanently water-wettable elastomeric films from a latex synthesized by polymerization of monomers in the presence of an amphiphilic block copolymer. By migration of the hydrophilic segments to the surface during film formation, the film is rendered essentially completely wettable by water. Applications may include flexible coatings that can introduce spatially selective wettability to solid surfaces, for example one-side wettable perforated films used for bandages and disposable diapers⁸.