Satya Shivkumar

Bio: Satya Shivkumar is an academic researcher from Worcester Polytechnic Institute. The author has contributed to research in topics: Electrospinning & Polymer. The author has an hindex of 19, co-authored 27 publications receiving 1823 citations.

N,N-Dimethylformamide Additions to the Solution for the Electrospinning of Poly(ε-caprolactone) Nanofibers

Abstract: Additives taht exhibit polyelectrolyte behavior such as N,N-dimethylformamide (DMF) may improve the electrospinning characteristics of viscoelastic polymer solutions. DMF additions to the solution lead to extensive jet splaying, thereby reducing the fiber diameter significantly. Nanofibrous structures with diameters of the order of 150 nm can be produced by the addition of about 10 vol.-% DMF to the solvent (chloroform). DMF additions also yield a narrow, unimodal distribution of fibers, compared to the bimodal distribution typically detected in electrospun polymers.

Bead-to-fiber transition in electrospun polystyrene

Abstract: The morphological transition, namely bead-to-fiber transition, of electrospun polymer was examined for polystyrene, with its molecular weight ranging from 19,300 to 1,877,000 g/mol. Tetrahydrofuran and N,N-dimethylformamide were used as solvents to examine the effects of solvent properties on the morphological variations. Polymer molecular weight and solvent properties had a significant effect on the morphology of beads as well as fibers. Observation of fiber diameter and its distribution suggested that the effect of molecular weight and solvent may be independent. The critical concentrations at which incipient and complete fibers were observed were found to decrease significantly with molecular weight, as can be expected. The effect of solvents on these critical concentrations was minimal for moderate to high-molecular-weight (>100,000 g/mol) solutions. For low-molecular-weight solutions, the transition occurred at concentrations much lower than those predicted by a model, based exclusively on chain entanglements. Rapid solidification of jet which is expected to occur with concentrated solutions may play a vital role in establishing stable fibers during electrospinning. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Nano-sized beads and porous fiber constructs of Poly(ε-caprolactone) produced by electrospinning

Abstract: Nano-sized beads and non-woven porous fiber constructs of poly(e-caprolactone) were produced by electrospinning. Nearly spherical beads with diameters between 900 nm and 5 μm were produced with dilute solutions with less than 3 wt% PCL. In this case, the initial jet of solution may split into many mini jets almost at the end of the needle and each minijet gradually disintegrates into small droplets. Beyond a critical solution concentration of about 4 wt% PCL, the jet may undergo extensional flow, splitting and splaying to produce a web of interconnected fibers with mean diameters on the order of 300 to 900 nm. Intermolecular entanglements play a dominant role in stabilizing the fibrous structure. A uniform fibrous structure was obtained at 40 kV while at 20 kV a large fraction of beads were present in the electrospun polymer. The fiber diameter in the PCL deposited on the collector typically exhibits a bimodal distribution. Electrospinning lowers the degree of crystallinity in the polymer.

Electrospinning: A Fascinating Method for the Preparation of Ultrathin Fibers

Abstract: Electrospinning is a highly versatile method to process solutions or melts, mainly of polymers, into continuous fibers with diameters ranging from a few micrometers to a few nanometers. This technique is applicable to virtually every soluble or fusible polymer. The polymers can be chemically modified and can also be tailored with additives ranging from simple carbon-black particles to complex species such as enzymes, viruses, and bacteria. Electrospinning appears to be straightforward, but is a rather intricate process that depends on a multitude of molecular, process, and technical parameters. The method provides access to entirely new materials, which may have complex chemical structures. Electrospinning is not only a focus of intense academic investigation; the technique is already being applied in many technological areas.

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

Abstract: Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made with regard to the development of electrospinning methods and engineering of electrospun nanofibers to suit or enable various applications. We aim to provide a comprehensive overview of electrospinning, including the principle, methods, materials, and applications. We begin with a brief introduction to the early history of electrospinning, followed by discussion of its principle and typical apparatus. We then discuss its renaissance over the past two decades as a powerful technology for the production of nanofibers with diversified compositions, structures, and properties. Afterward, we discuss the applications of electrospun nanofibers, including their use as "smart" mats, filtration membranes, catalytic supports, energy harvesting/conversion/storage components, and photonic and electronic devices, as well as biomedical scaffolds. We highlight the most relevant and recent advances related to the applications of electrospun nanofibers by focusing on the most representative examples. We also offer perspectives on the challenges, opportunities, and new directions for future development. At the end, we discuss approaches to the scale-up production of electrospun nanofibers and briefly discuss various types of commercial products based on electrospun nanofibers that have found widespread use in our everyday life.

Electrospinning of polymeric nanofibers for tissue engineering applications: a review.

Abstract: Interest in electrospinning has recently escalated due to the ability to produce materials with nanoscale properties. Electrospun fibers have been investigated as promising tissue engineering scaffolds since they mimic the nanoscale properties of native extracellular matrix. In this review, we examine electrospinning by providing a brief description of the theory behind the process, examining the effect of changing the process parameters on fiber morphology, and discussing the potential applications and impacts of electrospinning on the field of tissue engineering.