Thermoplastic semi-IPN of polypropylene (PP) and polymeric N-halamine for efficient and durable antibacterial activity

Crosslinked polyacrylamide (PAM) was durably immobilized onto polypropylene (PP) by forming a surface thermoplastic semi-interpenetrating network (IPN). Upon conversion of the immobilized amide to N-halamine, the PP substrate was imparted with durable and potent antibacterial activity. The successful modification was limited to one side of the PP fabric only as confirmed by XPS. After the surface modification, surface morphology of the fiber remained relatively unchanged, with only a slight increase in fiber diameter. When the immobilization percentage (IP) was less than 2.5%, a decrease of less than 6.6% in air permeability of the fabric was found. The tensile strength of the fabrics after the modification was well retained and even showed significant improvement as the IP exceeded 2.5%. After a sharp decrease in the first 4 regeneration cycles, the amount of N-halamine on the chlorinated polyacrylamide modified PP fabric leveled off up to 25 regeneration cycles. Even after 25 regeneration cycles, the chlorinated PAM–PP–D fabric was still able to result in 100% reduction of HA-MRSA in 30 min contact.