Polymer entanglement loss in extensional flow: Evidence from electrospun short nanofibers

Abstract

High strain rate extensional flow of a semidilute polymer solution can result in fragmentation caused by polymer entanglement loss, evidenced by appearance of short nanofibers during electrospinning. The typically desired outcome of electrospinning is long continuous fibers or beads, but, under certain material and process conditions, short nanofibers can be obtained, a morphology that has scarcely been studied. Here we study the conditions that lead to the creation of short nanofibers, and find a distinct parametric space in which they are likely to appear, requiring a combination of low entanglement of the polymer chains and high strain rate of the electrospinning jet. Measurements of the length and diameter of short nanofibers, electrospun from PMMA dissolved in a blend of CHCl3 and DMF, confirm the theoretical prediction that the fragmentation of the jet into short fibers is brought about by elastic stretching and loss of entanglement of the polymer network. The ability to tune nanofiber length, diameter and nanostructure, by modifying variables such as the molar mass, concentration, solvent quality, electric field intensity, and flow rate, can be exploited for improving their mechanical and thermodynamic properties, leading to novel applications in engineering and life sciences. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1377–1391

Effect of elongational flow on immiscible polymer blend/nanoparticle composites: a molecular dynamics study

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Template Assisted Change in Morphology from Particles to Nanofibers by Side‐by‐Side Electrospinning of Block Copolymers

“…In a highly concentrated solution with 50 wt.‐%, the particles became elongated, increased in size and were connected by thin fibers (Figure D). The increased particle size with increase in the polymer concentration and elongation of drops with even short fiber formation is well documented in the literature …”

“…The increased particle size with increase in the polymer concentration and elongation of drops with even short fiber formation is well documented in the literature. [5,10,30] In an electrospraying process, the electric field has a significant effect on the spraying jet. A stable jet can be obtained by applying a certain range of voltage, which is also a guarantee for the uniform particles.…”

Solvent-Free Aqueous Dispersions of Block Copolyesters for Electrospinning of Biodegradable Nonwoven Mats for Biomedical Applications

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