关键词: 静电纺丝, Janus纳米纤维膜, 制备方法, 水处理, 空气过滤, 生物医用

Abstract: The Janus separation membrane, a special kind of thin film material, is named for its two sides having different properties. One side of the Janus membrane is hydrophilic (oleophobic), while the other side is hydrophobic (oleophilic), which gives the Janus membrane a unique advantage in oil-water separation, membrane distillation, catalytic degradation and other fields. Electrospun Janus nanofiber membranes have attracted much attention due to their advantages of high specific surface area, slender fiber structure, and controllability. In order to better understand the research progress of electrospun Janus nanofiber membranes, this paper reviewed the recent research in this field. The preparation methods of electrospun Janus nanofiber membranes and their applications in various fields were highlighted.
First, this paper described the method and principle to prepare Janus nanofiber membranes through electrostatic spinning. In electrospinning, the polymer solution or melt was deformed under the action of high voltage electric field to form the "Taylor cone", and then the nanofibers were prepared by stretching, refining and curing. In this paper, the commonly used methods for the preparation of Janus nanofiber membranes based on electrospinning technology, such as sequential electrospinning, electrospinning combined with physical methods, and electrospinning combined with chemical methods, were summarized, and their principles, advantages and disadvantages were described in detail. 
Then, this paper detailed the applications of electrospun Janus nanofiber membranes in various fields. In this paper, recent advances in the application of Janus nanofiber membranes in oil-water separation were introduced. The synergistic role played by the sieving mechanism of porous structure and the aggregation mechanism of symmetrically selected wettability in the oil-water separation process was emphasized in this part. Secondly, its application in  membrane distillation was introduced. Researchers found that, in membrane distillation, the lower the resistance to pollution of the hydrophobic membrane is, the lower its permeability and separation efficiency will be. The unique porous structure and symmetrical selective wettability of the Janus nanofiber membrane can effectively improve its pollution resistance and enhance its membrane distillation performance. Then its application in catalytic degradation was described. Based on the multi-level controllable structure of electrospun Janus nanofiber membranes, researchers often introduce catalysts to give Janus nanofiber membranes excellent catalytic degradation performance, in order to remove dyes, heavy metal ions and other pollutants that cannot be thoroughly treated by physical separation. Finally, the applications of electrospun Janus nanofiber membranes inair filtration and biomedicine were introduced, which fully indicates that the unique structure and properties of electrospun Janus nanofiber membranes play an important role in in these two aspects..
In summary, this paper reviews the recent research progress of electrospun Janus nanofiber membranes, and introduces their preparation methods and applications in various fields. Through the discussion of their advantages and disadvantages, as well as the prospect of future development, it is hoped that the paper can provide some reference for the research and application of electrospun Janus nanofiber membranes.

Key words: electrospinning,  , Janus nanofiber membranes, preparation method, water treatment, air filtration, biomedical use