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Pre-electrospinning polymer solution treatment by atmospheric-pressure argon plasma jet

Electrospinning has been found to be a straightforward and flexible technique to produce novel fibers. This technique has obtained much attention in the last decade due to its advantages, including versatility in spinning a wide variety of polymeric fibers, its high stability, its reproducibility and its consistency in producing fibers with a diameter in the submicron range1. The morphology of the resultant nanofibers is directly affected by the polymer solution properties such as polymer concentration, surface tension, viscosity, electrical conductivity and solvent(s) volatility. Therefore, preparation of an appropriate polymer solution is of great importance in the electrospinning process. The capability of non-thermal plasma technology for treatment of various polymeric surfaces has been extensively investigated by many research groups. Also, plasma treatment has been used for enhancement of surface characteristics of electrospun nanofibers. However, only a handful of studies are available on the plasma treatment of polymeric solution. In the present study, an atmospheric-pressure argon plasma jet was used for the treatment of Poly lactic acid (PLA) dissolved in a chloroform/dimethylformamide mixture with different concentrations to enhance the electrospinnability of the polymer solutions. Plasma treatments were carried out with various exposure times and the viscosity, surface tension and conductivity of the PLA solutions were measured before and after plasma treatment. Optical emission spectroscopy (OES) was also performed during plasma treatment to investigate the characteristics of the atmospheric argon plasma jet generated in the polymer solution. Starting from the plasma-modified polymer solutions, nanofiber mats were also produced and the morphology of the nanofiber mats was examined by SEM.