Bio-inspired tubular hierarchical porous materials with selective liquids absorption

Cacti have an excellent ability to capture and store water in the air because of their unique hierarchical porous structure. Inspired by this, we proposed a hierarchical emulsion-tube-lattice (ETL) material, comprised of the lattice structure, tubular struts, and porous walls, with superior oil–water separation and storage capabilities. A one-step coaxial direct ink writing process was developed, with a silicone emulsion serving as the typical ink. After that, the oil absorption performances of the sample were evaluated. The results showed that the ETL material possesses higher oil absorption and retention capacity, and could allow the water of the water–oil mixture to pass through while absorbing the oil. Besides, the sample could reuse after squeezing out the oil and keep the soft mechanical properties. In summary, with the bio-inspiring design, the sample showed promising application in water–oil separation and storage. Furthermore, the method could be easily extended to other materials.