Thermo-controlled, self-released smart wood tailored by nanotechnology for fast clean-up of highly viscous liquids

Designing highly porous materials is of great importance for liquid separation, water purification, and disinfection, such as spill oil cleaning and recycling, seawater desalting, and oil/water separation. However, a remaining challenge is to produce porous materials with the characteristics of fast absorption, continuous directional transport, and self-release of viscous liquid. Herein, a functional cellulosic composite is reported by the chemical treatment and functionalization of wood resulting in a smart wood that can thermally self-release and separate high viscosity oil. The smart wood has a high absorption speed of 1398 mL/(m(2)center dot s) (ethylene glycol) and a maximum absorption capacity of 47.2 g/g (chloroform) due to its intrinsic vertical micro/nanoscale channel structure, low tortuosity, and high porosity. Moreover, the switchable wettability is achieved by the surface coating of poly(N-isopropylacrylamide) on the porous wood, which enables the collection and removal of oil from the oil/water mixture. The high viscosity oil can be automatically released due to the passive oil release at room temperature. The release capacity of the smart wood remains above 91% after 15 cyclic tests. We envision that this functional smart wood could be extended to a wide range of applications in smart hydrogels, microfluidics, artificial drug release, and environmental restoration.