Effect of Organic Photosensitizers on the Antimicrobial Property of Polyurethane coated Leather

Abstract: Cow leather coated with polyurethane film that contains various organic photosensitizers was investigated to demonstrate the antimicrobial properties in the application of the material to protective clothing and home appliances. To prepare the antimicrobial coating on leather surfaces with high potency against microbes, photoactive agents, such as benzophenone (BP), 4,4’-bis(dimethylamino) benzophenone (MK), 4,4’-dihydroxybenzophenone (DHBP) and methylene blue (MB), were incorporated into polyurethane-based coating solutions. The photoactive antimicrobial agent treated leather samples were characterized by SEM, color appearance, color fastness against abrasion, and antimicrobial tests. The optical properties of organic photosensitizers indicated that active UV absorbance ranges were different: BP (around 250 nm), MK (around 360 nm), DHBP (around 305 nm) and MB (around 295 nm &570 nm-685 nm). The intensity of the UV absorbance curve at the UVA light wavelength for the antimicrobial test showed the highest value with MK; subsequently, this was followed by MB, DHBP and BP in decreasing order. The treated-leather samples demonstrated excellent antibacterial activity under UVA light. The antimicrobial effects for the Staphylococcus aureus were superior to Escherichia coli. Moreover, the polyurethane finishing showed an effective durability to abrasion. The overall results indicated that DHBP is the most suitable PU coating additive to provide antimicrobial properties to leather as well as color and surface appearance than MK, MB, and BP. Key words: organic photosensitizer, antimicrobial coating, benzophenone derivative, leather finishing, polyurethane 1