Well-defined antibacterial block copolymers of 4-vinyl pyridine (4VP) and pentachlorophenyl acrylate (PCPA) (P(4VP-b-PCPA)) were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization. Electrospinning of the P(4VP-b-PCPA) from a solution in mixed tetrahydrofuran and dimethylformamide gave rise to fibers with diameters in the range of 0.5-4.0 mu m. The quaternary ammonium salts (QASs) were generated by N-alkylation of pyridine groups of P4VP block and chloro-aromatic compounds of PPCPA block (or self-quaternization of P(4VP-b-PCPA)). The self-quaternization of P(4VP-b-PCPA) nanofibers was studied by X-ray photoelectron spectroscopy. Attributable to the hydrophobicity of the PPCPA blocks and the electrostatic interaction of QASs generated from the self-quaternization of P(4VP-b-PCPA), the resulting nanofibers exhibit a high antibacterial efficiency. The antibacterial effect of the P(4VP-b-PCPA) nanofibers was assayed using Escherichia coli and Staphylococcus aureus cultures. It was found that 99.6% of E. coli and 99.1% S. aureus were killed after being in contact with 50 mg nanofibers in 10 min. The permanence of antibacterial activity of the self-quaternized P(4VP-b-PCPA) nanofibers was also demonstrated in repeat application.