Emulsion-templated, hydrophilic-oleophobic aerogels with flexibility, stretchability and recyclability

Abstract

Hydrophilic-oleophobic porous materials, especially those fabricated from one-pot emulsion templating, are promising for removing water from oil-water mixtures, but the relatively dense covalent crosslinking makes the materials rigid and impossible for recycling, which hinders their real applications. Herein, we report the fabrication of hydrophilic-oleophobic aerogels with flexibility, stretchability and recyclability through high internal phase emulsion templating. The aerogels were formed through the interface-initiated condensation of perfluorooctyltriethoxysilane within the dispersed phase and the subsequent solidification of external aqueous phase through poly(vinyl alcohol) gelation. The resulting aerogels exhibited controllable external shapes, good flexibility, robust compression, high stretchability, and in-air hydrophilicity-oleophobicity. These features enabled the aerogels to remove water from not only free oil-water mixtures but also surfactant-stabilized water-in-oil emulsions through selective absorption, and the aerogels also showed good reusability. Since the aerogels were formed through physical gelation, they could be recycled and reshaped by dissolving in hot water, adding oil, and freeze drying. The as-recycled aerogels showed similar properties to that of the parent aerogels.