Electrospinning is a straightforward and versatile method to fabricate ultrafine fibers with unique physical and chemical properties. However, the chaotic nature of traditional electrospinning limits its applications in devices which usually need arranged or patterned micro/nanoscale fibrous structures. In order to improve the controllable deposition of electrospun fibers, near-field electrospinning (NFES) has been proposed and developed in recent years. With characteristics of position-controlled deposition, NFES significantly expands the range of fiber-fabrication uses including electronic components, energy harvesting, flexible sensors, and tissue engineering. In this paper, the basic principle and research advances of NFES have been briefly reviewed. In particular, we summarize the process parameters, polymer materials, as-spun fibrous structures, modified apparatus, and potential applications of NFES. Finally, future prospects on the development tendency and challenges of NFES are discussed.

Electrospinning (e-spinning) has been extensively explored as a simple, versatile, and cost-effective method in preparing ultrathin fibers from a wide variety of materials. Electrospun (e-spun) ultrathin fibers are now widely used in tissue scaffold, wound dressing, energy harvesting and storage, environment engineering, catalyst, and textile. However, compared with conventional fiber industry, one major challenge associated with e-spinning technology is its production rate. Over the last decade, compared with conventional needle e-spinning, needleless e-spinning has emerged as the most efficient strategy for large-scale production of ultrathin fibers. For example, rolling cylinder and stationary wire as spinnerets have been commercialized successfully for significantly improving throughput of e-spun fibers. The significant advancements in needleless e-spinning approaches, including spinneret structures, productivity, and fiber quality are reviewed. In addition, some striking examples of innovative device designs toward higher throughput, as well as available industrial-scale equipment and commercial applications in the market are highlighted.

Electrospun nanofibrous membranes (NFMs) with outstanding photochromic property, waterproof, and breathability have attracted considerable interest owing to their multifunctional applications in intelligent clothing, self-cleaning, and protection. However, great challenges still remain in creating such functional materials. A novel waterproof-breathable membrane with robust photochromic property is fabricated by introducing photochromic microcapsule (PM) into electrospun thermoplastic polyurethanes (TPU) membranes. Compared with the pristine TPU NFMs, the composite TPU/PM membranes are endowed with reversible photochromic properties. In addition, the composite membranes not only exhibited a water contact angle of 1378 and a milk contact angle of 1308, but also had integrated properties of modest water vapor transmittance rate of 19,278 g m 22 day 21 , high air permeability of 962 mm s 21 , low waterproofness of 2.813 kPa, and comparable tensile strength of 12.08 MPa. Furthermore, the convenience and efficiency of this fabrication process will allow for large-scale production of the multifunctional NFMs. V C 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46342.

Electrospun nanofibers with designed or controlled structures have drawn much attention. In this study, we report an interesting new closed-loop structure in individual cerium nitrate/polyvinyl alcohol (Ce(NO 3 ) 3 /PVA) and NaCl/PVA fibers, which are fabricated by electrospinning with a nail collector. The electrospinning parameters such as voltage and Ce(NO 3 ) 3 (or NaCl) concentration are examined for the formation of the closed-loop structure. The results suggest that the increase of the spinning voltage or addition of Ce(NO 3 ) 3 (or NaCl) is favorable for the formation of the closed-loop structure, and the increase of loop numbers and the decrease of loop size. Further analyses indicate that the formation mechanism of the closed-loop fibers can be predominantly attributed to the Coulomb repulsion in the charged jets.