Reducing electrospun nanofiber diameter and variability using cationic amphiphiles

One major limitation of the electrospinning technique for generating polymer fibers is the large average diameter and the broad diameter variability of electrospun fibers. Improved methods of controlling fiber diameter and variability will have implications for many applications ranging from filtration to cell and tissue engineering. Here we report an effective method of reducing the diameter and variability of fibers prepared from three different polymers, poly(ethersulfone), poly(caprolactone), and poly(caprolactone-co-ethyl ethylene phosphoester), by doping polymer solutions with a positively charged amphiphile, octadecyl rhodamine (R18) or octadecyltrimethylammonium bromide (OTAB) at 5000:1 to 20:1 of polymer to amphiphile weight ratio. This is due to the combined effect of field-driven surface partitioning of positively charged amphiphiles and surface tension reduction. This method of diameter reduction can be applied easily without modifying the electrospinning setup or changing the polymer-solvent system.