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

Morphology transition in electrospinning polymers by a dual‐capillary system

“…Experimental results suggest that c f /c* is typically larger than 6.0 for single-capillary electrospinning systems. 33,37 On the basis of our survey, there is no report on the bead-to-fiber transition in a dual-capillary electrospinning system. The understanding of the solvent effects on the formation of fibers in dual-capillary setups is also very scattered.…”

“…In Figure 10 are summarized the bead-to-fiber transition data from Eda and Shivkumar 37 with our results for the dual-capillary system. To characterize the transition range, the figure is divided into three different regimes: the bead-only regime (identified as regime I in Fig.…”

“…A lack of elasticity of the solution prevents the formation of uniform fibers; instead, beads or bead-to-fiber structures are formed. 26,41,42 To simply identify the bead-to-fiber range, Eda, Gupta, McKee, Shenoy, and coworkers 27,28,[33][34][35]37 investigated morphological transitions based on critical hydrodynamic concentration, that is, the entanglement concentration (c e ) or critical chain overlap concentration (c*). Their research described the effect of the concentration on the breakup of a polymer solution jet in terms of two critical concentrations, the initial concentration (c i ) and final concentration of the transition range (c j ).…”

A review on electrospun bio-based polymers for water treatment

“…Both are directly dependent on the polymer molecular weight which defines the entanglement of the chains to withstand the Coulombic stretching force to prevent the jet breakage into droplets by surface tension [47][48][49][50]. The optimal concentration and/or viscosity are required because too high concentration/viscosity may result in larger diameter and clogging of the capillary [47][48][49][50]. Nevertheless, the gelation (highly viscous) at fairly low concentrations (below entanglement concentration) disrupts the electrospinnability of the biopolymers, resulting in collection of droplets.…”

Investigation of synthesis and processing of cellulose, cellulose acetate and poly(ethylene oxide) nanofibers incorporating anti-cancer/tumor drug cis-diammineplatinum (II) dichloride using electrospinning techniques

“…The wide array of adjustable parameters can be divided into three basic categories -solution, process and ambient parameters [6]. The solution parameters consist of the molecular weight of polymer [7,8], concentration [9][10][11][12], viscosity [13,14] surface tension [15] and conductivity [16]. The process parameters consist of voltage [17,18], flow rate [19], collector type [20,21] and distance between spinneret tip to collector [22,23].…”