Synthesis of polysiloxane with quaternized N-halamine moieties for antibacterial coating of polypropylene via supercritical impregnation technique

Abstract Development of polymers with enhanced biocidal ability to coated surfaces by a simple and versatile approach is very desirable in biomaterial area. A polysiloxane containing both quaternary ammonium and N-halamine was synthesized by silane alcoholysis between poly(methylhydrosiloxane) (PMHS) and 3-bromo-1-propanol, subsequent quaternization with 3-(3-(dimethylamino)propyl)-5,5-dimethylhydantoin (DMAPDMH), and chlorination with tert -butyl hypochlorite. The quaternized N-halamine polysiloxane was impregnated into polypropylene (PP) in supercritical carbon dioxide (scCO 2 ) and formed an antibacterial coating layer of 61 nm. The synthetic procedures and coating results were characterized using FTIR, NMR, XPS, and SEM. The polysiloxane layer showed enhanced synergetic antibacterial ability, providing a total kill of a 7-log S. aureus and E. coli within 10 min of contact. The rechargability and stability of the coating layer toward washing cycles, storage, and UV irradiation were good. This coating procedure uses environmentally benign CO 2 as solvent and affords a general method to functionalize inert polymers with biocidal capability.