Smart methylcellulose-based foams with thermal-induced volume shrinkage for efficient oil absorption and controllable recovery

Oil spill remediation is critical for environmental protection and sustainable resource management, yet conventional absorbents often face challenges in balancing rapid uptake and efficient oil release. Biomass-based polymers, such as cellulose derivatives, offer significant advantages for constructing advanced absorbents due to their renewability and functional tunability. In this study, we developed smart methylcellulose (MC)-based foams with multi-crosslinked networks and thermal-induced volume shrinkage for high-performance oil absorption and controllable recovery. The smart foams exhibit low density (12.73 mgꞏcm −3 ), high porosity (97.09 %), and excellent oil absorption capacity (up to 112.7 g/g). Furthermore, the foams demonstrate rapid temperature-triggered contraction, enabling effective extrusion and recycling of absorbed oil. By incorporating MXene nanosheets, the volume-shrinking oil discharge of the foam can be well enhanced with the assistance of sun illumination (shrinking to 63 % of original volume within 30 min under 1 sun irradiation, accompanied by a surface temperature rise to 91.9 °C), which promotes oil recycling with reduced energy consumption. It is expected that the smart foams with large oil-absorbing capacity and photothermal responsive oil discharge property present a sustainable and energy-efficient solution for environmental remediation.