Antibacterial effect of surface-functionalized polypropylene hollow fiber membrane from surface-initiated atom transfer radical polymerization

Microporous polypropylene (PP) hollow fiber (PPHF) membranes with surface-grafted block copolymer brushes of poly(ethylene glycol) monomethacrylate (PEGMA) and 2-(dimethylamino)ethyl methacrylate (DMAEMA) (PPHF-g-(PPEGMA-b-PDMAEMA)) were prepared via consecutive surface-initiated atom transfer radical polymerization (ATRP). The effective pore size of the surface modified PPHF membranes could be adjusted by controlling the graft chain length, or the ATRP time. Quaternization of the tertiary amine groups of the PDMAEMA block with 1-bromododecane gave rise to a high concentration of quaternary amine salt (QAS) on the PPHF membrane surface. The antibacterial effect of the quaternized PPHF-g-(PPEGMA-b-PDMAEMA) membrane was assayed with Escherichia coli (E. coli, a Gram-negative bacterium) and Staphylococcus aureus (S. aureus, a Gram-positive bacterium) cultures. In addition to bactericidal properties, the functionalized membrane surface also exhibited anti-fouling effect for bacteria due to the hydrophilic nature of the P(PEGMA) block on the PPHF-g-(PPEGMA-b-PDMAEMA) membrane. The permanence of antibacterial effect of the functionalized PPHF membrane was also demonstrated in repeated applications of the quaternized PPHF-g-(P(PEGMA)-b-PDMAEMA) membrane.