Investigation of plasma‐induced chemistry in organic solutions for enhanced electrospun PLA nanofibers

Abstract

Electrospinning is a versatile technique for the fabrication of polymer‐based nano/microfibers. Both physical and chemical characteristics of pre‐electrospinning polymer solutions affect the morphology and chemistry of electrospun nanofibers. An atmospheric‐pressure plasma jet has previously been shown to induce physical modifications in polylactic acid (PLA) solutions. This work aims at investigating the plasma‐induced chemistry in organic solutions of PLA, and their effects on the resultant PLA nanofibers. Therefore, very broad range of gas, liquid, and solid (nanofiber) analyzing techniques has been applied. Plasma alters the acidity of the solutions. SEM studies illustrated that complete fiber morphology enhancement only occurred when both PLA and solvent molecules were exposed to pre‐electrospinning plasma treatment. Additionally, the surface chemistry of the PLA nanofibers was mostly preserved.

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

“…An atmospheric-pressure plasma jet directly submerged in liquid phase was used in this study and has already been described in detail in previous studies. [11,19] Briefly, the system consisted of a 130-mm-long quartz tube (inside diameter: 1.5 mm), in which an aluminum rod electrode was embedded. A copper ring placed at a distance of 18 mm from the rod electrode and 40 mm from the end of the capillary served as ground electrode.…”

“…The effects of PEPT on the physical and chemical properties of the PLA solutions have already been carefully examined as well as the plasma-induced effects on the morphology of the resultant PLA nanofibers. [11,19] These studies revealed that PEPT induced significant changes to the conductivity, viscosity, and pH of the PLA solutions, resulting in an enhancement of electrospinnability and an improvement of PLA nanofiber formation. However, the effect of PEPT on the mechanical and thermal behaviors of the resultant PLA nanofibers as well as their crystalline structure still needs to be revealed.…”

“…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. [11,[19][20][21][22][23] For example, Shi et al [21,22] have treated polyethylene oxide (PEO) and polyacrylonitrile (PAN) solutions and observed the creation of finer and smoother nanofibers after electrospinning. In another study by Colombo et al, [20] plasma treatment was also found to promote the electrospinnability of poly-l-lactic acid (PLLA) solutions in dichloromethane resulting in the generation of nicely elongated smooth PLLA nanofibers.…”

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

“…So far, to the best of the author's knowledge, only five research papers have been published that deal with this subject. [23][24][25]31,32] Shi et al were the first to expose an aqueous solution of polyethylene oxide to an NTP and found remarkable improvements in fiber morphology. [24] Colombo et al followed a similar strategy, using an atmospheric pressure plasma jet (APPJ) to treat polylactic acid dissolved in dichloromethane and observed 100% bead-free fibers.…”

“…[25,32] 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. [31] Considering the positive results obtained in the abovementioned innovative papers, this work's intent was to examine the potential of pre-electrospinning plasma treatment of PEOT/PBT solutions for the fabrication of continuous beadfree PEOT/PBT nanofibers. For this purpose, a fixed concentration of 9 w/v% PEOT/PBT was dissolved in four different solvents: pure CHCl 3 , CHCl 3 + DMF, CHCl 3 + MeOH, and CHCl 3 + HFIP.…”