Layered gel emulsion-templated Janus porous composites for emulsified oil separation

Abstract

Efficient separation of emulsified oil is urgently needed to repair the ecological environment, given the explosive development in modern industrial civilization. Herein, Janus porous composites were constructed using two different paraffin oil-in-dimethylsulfoxide (DMSO) gel emulsions. One of the gel emulsions contained graphene oxide (GO) within the DMSO phase, while the other continuous phase was dissolved with triarm hydroxyl-terminated poly(ε-caprolactone) (PCL-triol). To create Janus porous composites, the gel emulsions were overlaid and solidified with poly[(phenyl isocyanate)-co-formaldehyde] through step-growth polymerization. The resultant GO/PCL Janus porous composites exhibited an asymmetric double-layer structure with a tightly bonded interface. GO/PCL Janus porous composites displayed asymmetric surface wettability, functioning as a liquid diode, and enabling effective separation of oil-in-water (O/W) miniemulsion. The separation efficiency could be further improved under simulated solar irradiation, due to heat-induced viscosity reduction and phase separation caused by the photothermal conversion effect of the GO-based layer. These Janus porous composites demonstrated excellent performance in oil-water separation, making them an ideal candidate for such applications.