Fluorocarbon-assisted surface orientation of N-halamine groups on cellulose in supercritical CO2: An effective and eco-friendly approach for developing higher biocidability

Preferential segregation of N-halamine structure to top surface to better contact with bacteria is demonstrated to be an effective tactic for achievement of higher biocidability. 5-Allylbarbituric acid and its fluorinated derivative, formed by sacrificing a imide hydrogen to tether a 4-perfluorohexylbutyl segment via nucleophilic substitution, were synthesized and separately attached to (50% methylhydrosiloxane)-dimethylsiloxane block copolymer (P(MHS-DMS)) via hydrosilylation. Chlorination of N-H bonds originating from barbituric acid produced two N-halamine polysiloxanes that were interpenetrated into cellulose to form coatings with similar morphology and thickness. Although containing similar to 50% less total content of chlorine than its nonfluorinated counterpart, polysiloxane with fluorinated pendants exerted faster inactivation against Staphylococcus aureus and Escherichia coli due to the orientation of its N-halamine groups on top surface with the assistance of the lowsurface-tension 4-perfluorohexylbutyl segment as verified by depth profiling using angle-dependent X-ray photoelectron spectroscopy (ADXPS). Design biocide with proper surface segregation ability therefore paves a new way for improved antibacterial efficacy. The stability and rechargeability of the biocidability of the coatings are satisfactory under washing cycles, UV irrigation, and storage.

Automated summary

The preferential segregation of N-halamine structure to the top surface for better contact with bacteria has been shown to be an effective strategy for achieving higher biocidability. The synthesis of fluorinated pendant polysiloxane demonstrated faster inactivation against Staphylococcus aureus and Escherichia coli, paving a new way for improved antibacterial efficacy. Designing biocides with proper surface segregation ability can lead to enhanced antibacterial effectiveness.