Preparation of biocidal 4-ethyl-4-(hydroxymethyl)oxazolidin-2-one-based N-halamine polysiloxane for impregnation of polypropylene in supercritical CO2

A cyclic N-halamine precursor, 4-ethyl-4-(hydroxymethyl)oxazolidin-2-one (EHMO), was synthesized and attached to poly(methylhydrosiloxane) (PMHS) through silane alcoholysis between the OH of EHMO and SiH of PMHS. The alcoholysis product was chlorinated with tert-butyl hypochlorite to transfer the NH to NCl and obtain an EHMO-based N-halamine polysiloxane. The N-halamine polysiloxane was impregnated into inert polypropylene (PP) fibers and formed a 72 nm coating layer using supercritical carbon dioxide (scCO(2)) as solvent and swelling reagent at 28 MPa and 50 degrees C for biocidal application. The overall synthetic procedure and the impregnation process were characterized by FTIR, XPS, and SEM, respectively. The N-halamine polysiloxane layer on PP imparted potent antibacterial abilities against both Staphylococcus aureus and Escherichia coli while pristine ones did not exhibit noticeable killing activities. Stability tests showed that the N-halamine polysiloxane layer was resistant to washing cycles, storage, and UV irradiation and the rechlorination of lost chlorines was good. The strategy of using CO2-philic PMHS as carrier polymer and scCO(2) as working solvent for impregnation presents a general and friendly procedure to functionalize inert substrates without the need of chemical linkage and organic solvent. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46624.