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[전기방사기 논문] Plasma Modifcation of Poly Lactic Acid Solutions to Generat…

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작성일2018-03-15 /   조회1,505회

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Fatemeh Rezaei , Anton Nikiforov, Rino Morent & Nathalie De Geyter Physical properties of pre-electrospinning polymer solutions play a key role in electrospinning as they strongly determine the morphology of the obtained electrospun nanofbers. In this work, an atmospheric-pressure argon plasma directly submerged in the liquid-phase was used to modify the physical properties of poly lactic acid (PLA) spinning solutions in an efort to improve their electrospinnability. The electrical characteristics of the plasma were investigated by two methods; V-I waveforms and Q-V Lissajous plots while the optical emission characteristics of the plasma were also determined using optical emission spectroscopy (OES). To perform a complete physical characterization of the plasma-modifed polymer solutions, measurements of viscosity, surface tension, and electrical conductivity were performed for various PLA concentrations, plasma exposure times, gas fow rates, and applied voltages. Moreover, a fast intensifed charge-couple device (ICCD) camera was used to image the bubble dynamics during the plasma treatments. In addition, morphological changes of PLA nanofbers generated from plasma-treated PLA solutions were observed by scanning electron microscopy (SEM). The performed plasma treatments were found to induce signifcant changes to the main physical properties of the PLA solutions, leading to an enhancement of electrospinnability and an improvement of PLA nanofber formation. Atmospheric-pressure non-equilibrium plasmas have recently gained increasing attention for diferent applications, such as decontamination and sterilization of surfaces or living tissues1 , surface activation2–4 , and liquid treatment5 . One of the emerging novel applications of these plasmas in the feld of plasma-liquid interactions is modifcation of pre-electrospinning polymer solutions6–8 . Electrospinning is a fber fabrication technique which relies on the application of electrostatic forces between a nozzle-tipped syringe containing the polymer solution and a collector for the deposition of nanofbers. As such, the polymer solution will be electrically charged and a Taylor cone will be formed at the nozzle tip. Overcoming the surface tension of the polymer solution, the electrostatic forces lead to the formation of a polymer jet from the nozzle tip towards the collector. While the polymer jet travels towards the collector, the solvents evaporate leading to nanofber deposition on the collector. Tis technique has gained more interest in recent years due to the large application potential of nanofbers in various felds including aerospace, energy generation and storage, fabrication of sensitive optical sensors, fltration, IT, and biomedical applications such as tissue engineering and drug delivery9–11. Usually, the production of uniform and bead-free fbers with desirable properties for a specifc application is not easy as multiple electrospinning parameters are known to determine the morphology of the resultant nanofbers. Tese parameters can be divided into three groups: electrospinning working parameters (such as applied voltage, feed rate, and working distance), properties of the electrospinning polymer solution, and ambient conditions12. Multiple studies have examined the efect of electrospinning working parameters and ambient conditions on numerous polymer solutions13–15, whereas the efect of the polymer solution properties (besides polymer concentration) on the electrospinning process have not been widely investigated. Nevertheless, the physical properties of the polymer solution such as concentration, viscosity, surface tension, and conductivity are known to be the main factors infuencing the electrospinnability of the solution as well as the fnal fber Research Unit Plasma Technology (RUPT), Department of Applied Physics, Faculty of Engineering and Architecture, Ghent University, St-Pietersnieuwstraat 41 B4, 9000, Ghent, Belgium. Correspondence and requests for materials should be addressed to F.R. (email: Fatemeh.Rezaei@UGent.be) 

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