Fabrication of a Self-Supported Nanoparticle-Decorated Amphipathic Film at a Liquid/Liquid Interphase

The design and facile fabrication of an amphipathic, mechanically durable, nanoparticle (NP)-decorated film has been realized at a liquid/liquid interphase. The innovative film is prepared by applying a changing electric field across an organic-aqueous interphase in the presence of 1-2 nm metal NPs, with a specific focus on Ir NPs in this work, self-assembled at the interphase, where the organic phase consists of a dissolved hydrophobic polymer in a volatile solvent. The electrochemical process leads to the oxidation of the Ir to IrOx, forming a hydrous oxide matrix at the interphase. With evaporation of the residual volatile solvent and precipitation of the polymer backbone, an isolable Ir/IrOx-decorated film is realized. The novelty of this technique stems from the ability to fabricate a substrate material in situ around a nanoparticle matrix, as opposed to transferring the matrix onto a substrate. The subsequent film exhibits a hydrophobic and a hydrophilic surface, permitting the film to reside at a water/oil, water/air, or oil/air interphase. The differences in wettability are attributed to the differences in the chemical and physical properties of the two sides of the film. Interestingly, despite both sides of the film exhibiting different wettabilities, both sides are electrochemically accessible. Several potential applications exist for this film, including the separation and collection of oil from water, in biosensors, and as catalyst layers.