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A Molecular-Level Picture of Electrospinning.
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SYSNO ASEP 0541364 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title A Molecular-Level Picture of Electrospinning. Author(s) Jirsák, Jan (UCHP-M) RID, ORCID, SAI
Pokorný, P. (CZ)
Holec, P. (CZ)
Dědičová, D. (CZ)Article number 2577 Source Title Water. - : MDPI
Roč. 12, č. 9 (2020)Number of pages 31 s. Language eng - English Country CH - Switzerland Keywords electrospinning ; polymer solution ; molecular dynamics Subject RIV CF - Physical ; Theoretical Chemistry OECD category Physical chemistry Method of publishing Open access Institutional support UCHP-M - RVO:67985858 UT WOS 000580120300001 EID SCOPUS 85092139041 DOI 10.3390/w12092577 Annotation Electrospinning is a modern and versatile method of producing nanofibers from polymer solutions or melts by the action of strong electric fields. The complex, multiscale nature of the process hinders its theoretical understanding, especially at the molecular level. The present article aims to contribute to the fundamental picture of the process by the molecular modeling of its nanoscale analogue and complements the picture by laboratory experiments at macroscale. Special attention is given to how the process is influenced by ions. Molecular dynamics (MD) is employed to model the time evolution of a nanodroplet of aqueous poly(ethylene glycol) (PEG) solution on a solid surface in a strong electric field. Two molecular weights of PEG are used, each in 12 aqueous solutions differing by the weight fraction of the polymer and the concentration of added NaCl. Various structural and dynamic quantities are monitored in production trajectories to characterize important features of the process and the effect of ions on it. Complementary experiments are carried out with macroscopic droplets of compositions similar to those used in MD. The behavior of droplets in a strong electric field is monitored using an oscilloscopic method and high-speed camera recording. Oscilloscopic records of voltage and current are used to determine the characteristic onset times of the instability of the meniscus as the times of the first discharge. The results of simulations indicate that, at the molecular level, the process is primarily driven by polarization forces and the role of ionic charge is only minor. Ions enhance the evaporation of solvent and the transport of polymer into the jet. Experimentally measured instability onset times weakly decrease with increasing ionic concentration in solutions with low polymer content. High-speed photography coupled with oscilloscopic measurement shows that the measured instability onset corresponds to the formation of a sharp tip of the Taylor cone. Molecular-scale and macroscopic views of the process are confronted, and challenges for their reconciliation are presented as a route to a true understanding of electrospinning. Workplace Institute of Chemical Process Fundamentals Contact Eva Jirsová, jirsova@icpf.cas.cz, Tel.: 220 390 227 Year of Publishing 2022 Electronic address https://www.mdpi.com/2073-4441/12/9/2577
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