Antibacterial Polymeric Nanofibers from Zwitterionic Terpolymers by Electrospinning for Air Filtration

A high-molecular-weight poly(styrene-co-2-(dimethylamino)ethyl methacrylate-co-acrylonitrile) (ABC)-type terpolymer with a high tensile strength (7.36 MPa) was synthesized using free radical polymerization. Sulfobetaine zwitterionic groups, N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl), were introduced into the ABC terpolymer, and electrospun nanofibers were fabricated for the removal of particulate matter particles in air streams. The nanofibers exhibit a high filtering efficiency (>99.9%) with a low pressure drop (177 Pa) at a constant airflow velocity of 5.3 cm s–1 with a quality factor of 0.025 Pa–1. Almost no effect on the filtering efficiency and pressure drop for nanofiber mats is observed even after treatment with saturated vapors of isopropyl alcohol for 24 h, confirming to ISO 16890. With fiber diameters in the range of 340–600 nm, the particle capture possibility is increased because of the large surface area compared to known electrospun nanofibers. The nanofibers also show an excellent antibacterial activity (99.9%) against the Gram-negative bacterium Klebsiella pneumoniae (ATCC 4352) and the Gram-positive bacterium Staphylococcus aureus (ATCC 6538) because of the presence of the sulfobetaine zwitterionic groups. The antibacterial property of nanofibers is desirable for air filter applications to prevent the spread of infectious agents such as viruses and bacteria.