Quat/malonylurea-based N-chloramine silane crosslinked on cotton for bactericidal synergism

The study reports a tactic for superior antibacterial performance on cotton via synergism of complementary functionalities of quaternary ammonium salt and malonylurea-based N-chloramine combined in a silane. Knoevenagel Condensation between 4-(chloromethyl)benzaldehyde and malonylurea formed a product whose chloromethyl group was used to quaternize tertiary amine of N,N-dimethylethanolamine. The O − H of the quaternization product was subsequently alcoholyzed with Si − H of trimethoxysilane. The methoxysilyl groups of the alcoholysis silane were hydrolyzed to silanol ones that condensed with either their own kind or hydroxy groups of cellulose to polymerize into a crosslinked polysiloxane finishing on cotton. Upon chlorination of malonylurea-based N − H bonds, each repeating unit of the polysiloxane has one quaternary ammonium salt and two imide N-chloramine sites. Antibacterial assays against Staphylococcus aureus and Escherichia coli proved that the synergism of quaternary ammonium salt and N-chloramine, a higher efficacy and a broader spectrum arising from their complementary elimination mechanisms and physiochemical features. Biocidal stability and rechargeability of the polysiloxane finishing were both promising due to the robust and hydrophobicity of silicone backbone and the sturdy cyclic N-chloramine. This research presented a general approach for generation of super biocidability on substrates that can react with hydroxy group using silanes to carry complementary functionalities.