Design of Infused-Liquid-Switchable Superamphiphilic and Flame-Retardant Hierarchically Porous Materials from Emulsion-Templated Technique

The serious oil pollution from oil spillages and industrial processes not only causes severe environmental and ecological damage but also creates a risk of fire and explosion. Therefore, it is imperative, also challenging, to find high-performance oil/water separation materials that are effective and incombustible. Herein, hierarchically porous polyphosphazene (PSZ) monoliths, having an intelligent superamphiphilicity and high flame retardance, are constructed via an emulsion-templating strategy. A high-temperature-resistant high internal phase emulsion (HIPE) is designed for the first time to synthesize PSZ from hexachlorocyclotriphosphazene and 3, 3′-diaminobenzidine. The synthesis of PSZ guarantees the formation of a mesostructured framework. Meanwhile, the droplets of the emulsion as sacrificial templates provide the formation of micron-scale voids in the monolith. The hierarchically porous structure combining the amphiphilic nature of PSZ endows the monolith with an infuse-liquid-switchable superamphiphilic performance, i.e., superhydrophobic under oil and superoleophobic under water. Also, due to its highly permeable structure, the PSZ monolith is proven to be highly efficient for continuously and simultaneously separating oil and water from emulsion. Moreover, the intrinsic flame retardance of PSZ makes the monolith possess excellent flame retardancy (UL-94-V-0 grade, LOI of 27.4%), which is thus expected to reduce the risk of fire and explosion when being used to separate oil and water.