Influence of Processing Conditions on Polymorphism and Nanofiber Morphology of Electroactive Poly(vinylidene fluoride) Electrospun Membranes

Abstract Poly(vinylidene fluoride) (PVDF) electrospun membranes are obtained from a 20% w/w solution of the polymer in dimethyl formamide. Processing parameters are systematically changed to analyze their influence on fiber morphology, fiber orientation, and on the crystallinity and crystal phase of the membranes. The PVDF concentration and travelling distance from the needle to the collector are kept fixed while the influence of the flow rate, needle diameter, applied voltage, and rotating collector speed is considered. The study allows concluding that those parameters leading to a higher stretching of the jet or straining of the fibrils during collection favor the formation of the electroactive β-phase while the total crystalline fraction depends only slightly on the electrospinning conditions. Keywords: Electroactive membranesElectrospinningPolymorphismPoly(vinylidene fluoride)PVDF ACKNOWLEDGMENTS The SEM was conducted by the authors with the kind help of José Carlos Rodríguez in the Microscopy Service of the Universidad Politécnica de Valencia, whose advice is greatly appreciated. We thank the Centro for Nano and Microtechnologies (CENTI), Famalicão, Portugal, for allowing for laboratory support. The authors thank the Portuguese Foundation for Science and Technology (FCT) Grants PTDC/CTM/73030/2006, PTDC/CTM/69316/2006 and NANO/NMed-SD/0156/2007. V.S. thanks the FCT for the SFRH/BPD/63148/2009 grant. C.R. thanks the INL for a Ph.D. grant. J.L.G.R. acknowledge the support of the Spanish Ministry of Education through project No. MAT2007–66759–C03–01 (including the FEDER financial support and founding in the Centro de Investigación Principe Felipe in the field of Regenerative Medicine through the collaboration agreement from the Conselleria de Sanidad (Generalitat Valenciana), and the Instituto de Salud Carlos III (Ministry of Science and Innovation)).