Photothermal-Responsive and Flame-Retardant CB/APP/PNIPAM Electrospun Composite Membrane for Efficient Oil–Water Separation

Multifunctional membranes with rapid responsiveness and high fire safety are highly desirable for oil–water separation, yet integrating photothermal responsiveness, thermoresponsive wettability, and flame retardancy into a single membrane remains challenging. Herein, a multifunctional CB/APP/PNIPAM@PP composite membrane was successfully fabricated on a polypropylene (PP) nonwoven substrate via a facile one-step electrospinning strategy. The membrane exhibits reversible wettability switching from superhydrophilicity (∼0° at 20 °C) to hydrophobicity (119° at 60 °C) owing to the lower critical solution temperature (LCST) behavior of PNIPAM. Under one-sun irradiation, the membrane temperature rapidly increased to approximately 66 °C within 420 s, enabling photothermal regulation of surface wettability. Meanwhile, the limiting oxygen index increased from 16.1% for pristine PP to 26.3%, indicating significantly improved flame retardancy. The membrane also exhibited adsorption capacities of 8.49–31.58 g g–1 toward various oils and organic solvents and achieved separation efficiencies above 95% for different surfactant-stabilized water-in-oil emulsions. This work provides a simple strategy for integrating photothermal responsiveness, thermoresponsive wettability, flame retardancy, and oil–water separation into a single electrospun membrane, demonstrating its potential for multifunctional oil–water separation applications.