Plasma Modification of Poly Lactic Acid Solutions to Generate High Quality Electrospun PLA Nanofibers

Abstract

Physical properties of pre-electrospinning polymer solutions play a key role in electrospinning as they strongly determine the morphology of the obtained electrospun nanofibers. 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 effort 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-modified polymer solutions, measurements of viscosity, surface tension, and electrical conductivity were performed for various PLA concentrations, plasma exposure times, gas flow rates, and applied voltages. Moreover, a fast intensified charge-couple device (ICCD) camera was used to image the bubble dynamics during the plasma treatments. In addition, morphological changes of PLA nanofibers generated from plasma-treated PLA solutions were observed by scanning electron microscopy (SEM). The performed plasma treatments were found to induce significant changes to the main physical properties of the PLA solutions, leading to an enhancement of electrospinnability and an improvement of PLA nanofiber formation.

Fabrication of PEOT/PBT Nanofibers by Atmospheric Pressure Plasma Jet Treatment of Electrospinning Solutions for Tissue Engineering

“…followed a similar strategy, using an atmospheric pressure plasma jet (APPJ) to treat polylactic acid dissolved in dichloromethane and observed 100% bead‐free fibers . In our research group, an extensive study on the effects of NTP exposure on a solution of PCL or PLLA in CHCl 3 and DMF was recently performed . It was found that the plasma was responsible for improving the conductivity of the polymer solution as well as changing the viscosity and pH via the generation of new chemical species without damaging the macromolecular structure of the polymer …”

“…However, the use of NTP to alter the properties of polymeric solutions (for electrospinning) is a field of research that has barely been touched upon. So far, to the best of the author's knowledge, only five research papers have been published that deal with this subject . Shi et al.…”

“…Successively, a mixture of chloroform and DMF (10 v/v%) was also explored as DMF has a high dielectric constant and aprotic properties, which could positively affect PEOT/PBT electrospinnability. In addition, the mixture CHCl 3 + DMF has already been extensively studied in our previous works focusing on PCL and PLA with successful electrospinning results . Third, a mixture of chloroform and MeOH (10 v/v%) was examined as methanol is also characterized by a high dielectric constant and presents a protic behavior and may thus positively affect PEOT/PBT electrospinnability.…”

The Influence of Pre‐Electrospinning Plasma Treatment on Physicochemical Characteristics of PLA Nanofibers

“…Attention and interest in nanofiber technology has substantially grown in the last decades due to their unique properties and many potential biomedical applications such as tissue engineering scaffolds, wound dressings, drug delivery devices as well as many other industrial applications . In the biomedical field, there is a great tendency to use nanofibers generated from biodegradable polymers due to their similarity to native tissues which is believed to result in improved cell interactions and extracellular matrix generation .…”

“…Taking this into account, pre‐electrospinning plasma treatment (PEPT) of polymer solutions has already been investigated by several research groups, including ours, as an innovative and environmentally friendly method to change polymer solution properties in an effort to increase the electrospinnability of these solutions . For example, Shi et al have treated polyethylene oxide (PEO) and polyacrylonitrile (PAN) solutions and observed the creation of finer and smoother nanofibers after electrospinning.…”