Smart superwetting COF membrane for controllable oil/water separation

•A series of COF membranes with tunable wettability were constructed using COF nanofibers by filtration assembly.•The membrane exhibits superior robustness and flexibility and can be easily peeled off from substrates into a self-standing membrane.•The membrane can achieve switchable separation of light oil/water, heavy oil /water, water-in-oil and oil-in-water emulsion.•The membrane presents excellent stability and recyclability.