Synthesis of pyridinium polysiloxane for antibacterial coating in supercritical carbon dioxide

Antibacterial polysiloxane with pyridinium pendants was synthesized through hydrosilylation reaction of trimethylsiloxane terminated (45% methylhydrosiloxane)-dimethylsiloxane random copolymer and 4-vinylpyridine and subsequent N-alkylation of pyridine ring with 1-bromohexane. The pyridinium polysiloxane was coated on cotton and formed a 35 nm layer via a novel method of deposition in supercritical carbon dioxide (scCO(2)) for biocidal application. The coated fabrics provided effective antibacterial activities against both Staphylococcus aureus and Escherichia coli compared with uncoated ones that did not exhibit noticeable biocidal activities. The pyridinium polysiloxane coating layer on cotton was stable toward storage in air and washing cycles. The scCO(2) deposition technique uses ecologically responsible CO2 as solvent and is hypothesized to work on both reactive and nonreactive surfaces due to without the use of covalent tethering groups. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41723.