New Refreshable N-Halamine Polymeric Biocides: N-Chlorination of Acyclic Amide Grafted Cellulose

Acyclic N-halamine structures have demonstrated antibacterial functions similar to cyclic N-halamine. Precursors of acyclic halamine such as acrylamide and methacrylamide can be easily grafted onto surfaces of substrates via radical polymerization processes. However, due to easy hydrolysis of primary amides during chlorination and steric hindrance of secondary amide to conversion to acyclic halamine structures, the acyclic halamines still have limitations to many applications in preparation of antimicrobial materials. To reduce hydrolysis of amide during chlorination, particularly under alkaline conditions, addition of electrolytes such as NaCl was able to improve chlorination of polyacrylamide grafted cotton (chlorine content 458 ppm) with less than 10% hydrolysis under slightly basic (pH = 8) conditions. Both acidic conditions and the addition of salt can increase the chlorination of secondary an-fides and provide effective antibacterial functions on the treated cellulose (5 log reduction of E. coli in contact time of 120 min).