3D cellulose scaffold with gradient pore structure controlled by hydrogen bond competition: Super-strength and multifunctional oil/water separation

Cellulose-based aerogels offer exceptional promise for oily wastewater treatment, but the challenge of low mechanical strength and limited application functions persists. Inspired by the graded porous structures in the animal skeleton and bamboo stem, we firstly report here a stepwise solvent diffusion-induced phase separation approach for constructing the gradient pore-density three-dimensional (3D) cellulose scaffold (GPDS). Benefiting from the regulation of competitive hydrogen bonding between the anti-solvents and the ionic liquid (IL) in cellulose solution, GPDS exhibits the decreased major channels size and increased minor pores amount gradually along the solvent diffusion direction. These endow GPDS with the characteristics of low density (0.019 g/cm) and super strength (high up to 870 KPa). The application of GPDS in the field of oil-water separation has achieved remarkable results, including oil/organic solvent absorption (13-25 g/g