Preparation of a Janus-polyvinylidene fluoride micro/nano fiber membrane by centrifugal spinning and investigation into its unidirectional water transfer and oil–water separation functions

Traditional oil–water separation membranes have a high energy consumption and complicated operation. To solve this problem, an asymmetric wetting polyvinylidene fluoride (PVDF) fiber membrane with a hydrophobic side and a hydrophilic side was prepared. Octamethylcyclotetrasiloxane was grafted onto one side of a centrifugal spun PVDF fiber membrane by plasma initiation, and dopamine was sprayed on the other side of the fiber membrane. The Janus-PVDF fiber membrane prepared can separate a mixture of water and dibromoethane, a toluene–water emulsion and a mixture of n-hexane and water. The initial interception rates were 98.53% ± 1.31%, 98.52% ± 1.12% and 98.61% ± 1.23%, respectively. After five cycles of separation, the separation rates remained at 96.15% ± 1.25%, 95.02% ± 1.21% and 96.91% ± 1.42%, respectively. The Janus-PVDF fiber membrane has excellent unidirectional water transfer capability and possesses well-repeated separability. The preparation of its unique Janus structure also provides a new direction for the field of oil–water separation.