Coaxial Electrospinning for Nanostructured Advanced Materials

Abstract

Electro-hydro-dynamic (EHD) compound jets, with diameters in the micro and nanometric size range, from conical menisci of two co-flowing liquids, is a consolidated platform for the production of nanofibers with inner structure, in a process so-called coaxial electrospinning or co-electrospinning. In contrast to other multi-step template based procedures, the EHD methodology is much more simple and general since, firstly, a solid template is needless and, secondly, the process is seldom affected by the chemistry of the liquids. This gentle process allows selecting the liquid precursors depending on the application sought for the nanofibers. Here, we review different products obtained by this EHD technique: (1) solid and hollow carbon nanofibers from different precursors (polyacrylonitrile, polyvinylpyrrolidone and lignin), (2) nanofibers of biocompatible polymers encapsulating liquids in the form of beads, (3) spinning nanofibers of alginate and (4) in-fiber encapsulation of active microgels.

Coaxial Electrospinning of Self‐Healing Coatings

“…One major advantage of this process is that it utilizes purely physical forces to form the core/sheath structure, thus overcoming the rather serious limitations exhibited by methods that require a minimum emulsion stability for chemical reactions to take place and hold the capsule together. [13,14] This feature makes it suitable for processing a broader variety of materials for self-healing. Another advantage of this simple one-step coaxial electrospinning encapsulation method is the inherent flexibility in controlling the diameter of the microcapsules and connecting ligaments from the micro-to nanometer scales.…”

“…If the proper combination of liquids and operation conditions are satisfied, a layered Taylor cone can be developed and a coaxial jet can be formed when a high voltage is applied to the outer metallic capillary. [13,[15][16][17] The electro-hydro-dynamic forces smoothly stretch the fluid interface to generate coaxial fibers due to the electrostatic repulsion between the accumulated surface charges. A two-part healing agent system was electrospun in two steps onto various substrates, a steel substrate being the most useful experimentally.…”

Fischer-Tropsch synthesis over lignin-derived cobalt-containing porous carbon fiber catalysts

“…Among the different technologies for the preparation of carbon fibers (CFs), electrospinning has emerged in recent years as a simple and versatile technique for the preparation of novel binderless lignin-based submicron CFs, using high voltage electrical fields and a spinnable precursor solution [30,[36][37][38][39]. The properties of the CFs can be modulated by adding different heteroatoms to the initial lignin/ethanol solution and even ceramic/lignin composite fibers can be prepared instead, with a few modifications of the configuration set-up (coaxial and triaxial configurations) [40]. In the former case, metal-containing CFs can be obtained in a single step with very well dispersion of the heteroatom, which increases the dopant active surface of the catalyst [37][38][39].…”