Preparation of polyimide nanofiber membrane with gradient wettability by electrospinning

Abstract

Radial polyimide(PI) nanofiber membrane was prepared on an asymmetric electrode by electrospinning.The morphology and arragement of the nanofiber on the PI membrane were observed by environmental scanning electron microscope(ESEM).The wettability was characterized by the apparent contact angle and the surface adhesive effect was characterized by the high-sensitivity microelectromechanical balance system.The effect of the microstructures on the contact angle and adhesive force was analyzed.The experimental results show that the PI nanofibers exhibit novel gradient microstructures.Particularly,the PI nanofibers were in a radial pattern from dense to sparse along the direction of triangular electrode to curved electrode.The diameter of the PI nanofibers was uniform and their surfaces were smooth.The distance between the adjacent fibers was from a few microns to tens of microns.The unique gradient microstructure of PI nanofiber membrane results in the gradient density of the surface chemical substance and they are crucial to the gradient changes of the contact angle and adhesive force.