In this study, polyurethane cationomers (PUCs) containing different amounts of quaternary ammonium groups were synthesized and successfully electrospun into non-woven nanofiber mats for use in antimicrobial nanofilter applications. The PUCs showed very strong antimicrobial activities against Staphylococcus aureus and Escherichia coli. The average diameters of the electrospun PUCs fibers decreased with increasing quaternary ammonium group content due to the increased charge density of the PUC solutions. The PUC nanofibers showed adhesion between nanofibers with various bonding sites, yielding mats with a film-like character and structural integrity. (c) 2007 Elsevier B.V. All rights reserved.