A Review on the Secondary Surface Morphology of Electrospun Nanofibers: Formation Mechanisms, Characterizations, and Applications

Engineering the secondary surface morphology of fibers (fibers without smooth surface and solid interior) has been attracting significant awareness in various areas and applications. Among different methods of forming nanofibers, electrospinning is the most widely adopted technique due to the ease of forming fibers with a broad range of properties and its unique advantages such as the flexibility to spin into a variety of shapes and sizes as well as adjustable porosity of electrospun structures. In this review paper, more emphasis is put on the secondary surface morphology. A comprehensive overview of the basic principles about the electrospinning process, types of electrospinning, materials, formation mechanisms, characterizations, and applications of electrospun fibers with the secondary surface morphology (e. g. the porous structure, grooved structure, wrinkled structure, rough structure, cactus structure, and hollow structure) are discussed in detail. Importantly, we believe our work can serve as guidelines for the preparations, characterizations, and applications of electrospun fibers with the secondary surface morphology.