Microfluidic Generation of Bioinspired Spindle-knotted Graphene Microfibers for Oil Absorption

Graphene materials have a demonstrated value in water treatment. Efforts to promote these materials are focused on the generation of functional graphene adsorbents for effectively removing contaminants from water. Here, inspired by the conformation of spider silks, we present a novel graphene microfiber material with spindle-knotted microstructures by using a microfluidic emulsification and spinning collaborative technology. The size and spacing of the spindle-knots were highly controllable by adjusting the flow rates of microfluidics during the generation process of the microfibers. The generated microfibers could adsorb oil from a water-oil mixed environment due to their hydrophobic surface chemistry. Because of the surface energy curvature gradient and the difference in Laplace pressure, the collected oil tended to form droplets and move from joints between the spindle-knots to the knots. In addition, by encapsulating additional functional elements, such as magnetic nanoparticles, the graphene microfiber with the ability to control and facilitate the collection of oily contaminants can also be achieved. These features greatly prove the promising values of the spindle-knotted graphene microfibers in the protection of the environment.