Electrospinning: The State of Art Technique for the Production of Nanofibers and Nanofibrous Membranes for Advanced Engineering Applications

The electrospinning technology leaves an indelible mark in the successful production of continuous fibers with average diameter in submicron to nanometre scale range, primarily by using an electric force to induce the charged filaments of polymer solutions or melts, which gained the invigorated attention of the scientific community due to its versatile, cost-effective, and easy production of continuous ultrafine fibers from a wide variety of materials like polymers, metals, ceramics, and composites. Electrospinning is a relatively simple procedure to undertake in a laboratory as it requires minimal equipment and this method does not need high temperatures and/or coagulation chemistry to yield ultrafine fibers from polymer solution, which results in the predominant production of fibers using bulky and composite molecules. However, the physics and fiber forming mechanism behind the process is complex. According to the mechanism of the electrospinning process, the basic electrospinning setup contains a high-voltage system, mono- or multi-spindle spinneret equipped with a pressure pump, and a grounded stationary or rotating collector. This cost-effective synthetic method produces fibrous flexible membranes possessing high aspect ratio as well as applicable for large-scale industrial production. The present chapter focuses on the historical development of electrospinning process, principle behind electrospinning technique, major parameters that govern the fiber morphology as well as architecture of the polymer membranes and their engineering applications in different fields. The submicron-sized fibers as well as fibrous nonwoven fabric produced by this mature technique found a variety of applications in textile industries, filtration, tissue engineering scaffolding, drug delivery, energy storage devices, flexible nanosensors, cosmetic skin mask, composite technology, etc. The fiber structure, average fiber diameter, fiber orientation, and morphology of these one-dimensional nano-architectures are controlled by varying the spinning parameters such as solution properties, process parameters, ambient parameters. To gain a vivid understanding of all these process variables and electrostatic inter relations involved in electrospinning, special consideration must be given to polymer chemistry, fluid mechanics, electric field interactions, environmental conditions and kinetics. And thus, the current chapter also discusses the different electrospinning techniques, effect of various spinning parameters on the properties of the fibres as well as the relevant theoretical fiber forming mechanisms involved in the spinning process.