Solvent-resistant antibacterial microfibers of self-quaternized block copolymers from atom transfer radical polymerization and electrospinning

Diblock copolymers with one block of poly[((2-dimethylamino)ethyl methacrylate)-co-(glycidyl methacrylate)] P(DMAEMA-c-GMA) and another of poly(pentachlorophenyl acrylate) (PPCPA) (P(DMAEMA-c-GMA)-b-PPCPA) were synthesized via consecutive atom transfer radical polymerization (ATRP). Electrospinnning of P(DMAEMA-c-GMA)-b-PPCPA from a solution in THF and DMF gave rise to microfibers with diameters in the range of 300 nm to 1.3 μm. Solvent-resistant microfibers were obtained by the subsequent treatment with 1,6-hexanediamine. The quaternary ammonium salts (QASs) were generated viaN-alkylation of tertiary amine groups of the P(DMAEMA-c-GMA) block by the chloro-aromatic compounds of the PPCPA block (or self-quaternization of P(DMAEMA-c-GMA)-b-PPCPA). Combination of the hydrophobic interaction of the PPCPA and the electrostatic interaction of QASs from the self-quaternization of P(DMAEMA-c-GMA)-b-PPCPA gives the resulting microfibers a high antibacterial activity. The antibacterial effect of the crosslinked microfibers was assayed with Escherichia coli and Staphylococcus aureus cultures. 95% E. coli and 97% S. aureus were killed after being contacted with 50 mg P(DMAEMA-c-GMA)-b-PPCPA microfibers in 10 min. The permanence of the antibacterial activity of the self-quaternized P(DMAEMA-c-GMA)-b-PPCPA microfibers was also demonstrated in repeated applications.