Conferring durable antimicrobial properties on nonwoven polypropylene via plasma-assisted graft polymerization of DADMAC

Spunbond nonwoven polypropylene (SB-PP), commonly used for hygienic products, was treated with diallyldimethylammonium chloride (DADMAC) to confer antimicrobial properties. Atmospheric pressure glow discharge plasma was used to induce free radical chain growth polymerization of DADMAC monomer onto the SB-PP in the presence of a crosslinker, which produced a graft polymerized network on the fabric with durable antimicrobial properties. The effects of different DADMAC concentrations and plasma operating condition parameters including the RF power (400-800 W) and the time of plasma exposure (0-120 s) were studied and the optimum treatment conditions were identified by determining the surface charge density on the treated fabrics. The presence of grafted poly-DADMAC on the polypropylene surface was confirmed using SEM, FT-IR and TOF-SIMS techniques. Antibacterial performance was investigated using the AATCC Test Method 100 for both gram positive and gram negative bacteria, and the antimicrobial test results showed 6 log reductions in the number of bacterial activities of Klebsiella pneumoniae and Staphylococcus aureus on the SB-PP samples, which is unprecedented.