Atmospheric Pressure Non-Equilibrium Plasma Treatment to Improve the Electrospinnability of Poly(L-Lactic Acid) Polymeric Solution Vittorio Colombo,* Davide Fabiani, Maria Letizia Focarete,* Matteo Gherardi, Chiara Gualandi, Romolo Laurita, Marco Zaccaria This work is focused on the use of non-thermal plasma to improve the electrospinnability of poly(L-lactic acid) (PLLA). The use of toxic high boiling point solvents is minimized to produce high quality solvent free nanofibrous scaffolds for biomedical applications. PLLA polymeric solutions dissolved in pure dichloromethane are exposed to the plasma plume of a jet developed by some of the authors and driven by high voltage pulses with rise rate of several kV ns À1 . The effects of peak voltage, pulse repetition frequency, volume of the solution and treatment time on the morphology of electrospun fibers are investigated by means of scanning electron microscope. Electrospinning is per- formed at different time lapses after the plasma treatment to study the durability of the induced effects. 1. Introduction Electrospinning is a well established and versatile technol- ogy to fabricate continuous polymeric or inorganic fibers having dimensions ranging from tens of nanometers to a few microns and typically assembled into non-woven mats, starting from a jet of an electrostatically charged molten polymer or of a polymeric solution. [1] It is well known that such polymeric solutions should fulfil many requirements, in terms of rheological properties, electrical conductivity, and surface tension, in order to be electrospinnable. [2,3] Specifically, high viscosity, high charge density, and low surface tension interplay in the formation and evolution of the electrospinning jet and are key factors in controlling fiber morphology and in producing bead-free fibers. [4] Beads are typical undesired defects along the fiber axis that worsen mat mechanical properties, being commonly responsible of mat increased fragility. [5] Most polymers have low dipole moments and can be dissolved only in non-polar solvents that, however, are not suitable for V. Colombo, M. Gherardi, R. Laurita Department of Industrial Engineering (DIN), Alma Mater Studiorum – Universit a di Bologna, Via Saragozza 8, 40123 Bologna, Italy E-mail: vittorio.colombo@unibo.it V. Colombo, D. Fabiani, C. Gualandi Advanced Mechanics and Materials – Interdepartmental Center for Industrial Research (AMM-ICIR), Alma Mater Studiorum – Universit a di Bologna, Via Saragozza 8, 40123 Bologna, Italy D. Fabiani, M. Zaccaria Electrical, Electronic and Information Engineering Department (DEI), Alma Mater Studiorum – Universit a di Bologna, Viale Risorgimento 2, 40136 Bologna, Italy M. L. Focarete, C. Gualandi Department of Chemistry ‘‘G. Ciamician’’ and National Consortium of Materials Science and Technology (INSTM, Bologna RU), University of Bologna, Via Selmi 2, 40126 Bologna, Italy E-mail: marialetizia.focarete@unibo.it M. L. Focarete Health Sciences and Technologies – Interdepartmental Center for Industrial Research (HST-ICIR), Alma Mater Studiorum – Universit a di Bologna, Via Tolara di Sopra 50, 40064 Ozzano dell’Emilia, Italy Full Paper Plasma Process. Polym. 2014, 11, 247–255 ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 247 DOI: 10.1002/ppap.201300141 wileyonlinelibrary.com