The antibacterial activity and mechanism of polyurethane coating with quaternary ammonium salt

An antibacterial PU coating with QAS was developed from polycarbonate diol (PCDL), 4,4'-Diphenylmethane diisocyanate (MDI), 3-dimethylamino-1,2-propanediol (DMAPD) and 1-bromododecane. The structural composition and surface morphology of this PU coating were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). Besides, the QAS-bearing PU showed markedly antimicrobial activity against both gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli). The samples were marked as PU-2, PU-3, PU-4, PU-5, PU-6 and PU-7 according to the different theoretical molar fraction of DMAPD in chain extenders, which were 20, 30, 40, 50, 60 and 70%, respectively. Apparently, PU-4 coating showed the best antibacterial activity against S. aureus, whereas PU-5 against E. coli.