In this study,a novel waterborne polyurethane(WPU)with azobenzene-containing(azo-containing)pendant groups was synthesized by isophorone diisocyanate,long-chain diol of polycaprolactone,2-ethyl-2-methyl-butanoic acid(...In this study,a novel waterborne polyurethane(WPU)with azobenzene-containing(azo-containing)pendant groups was synthesized by isophorone diisocyanate,long-chain diol of polycaprolactone,2-ethyl-2-methyl-butanoic acid(2,2-dimethylolpropionic acid),10-(4-(phenyldiazenyl)phenoxy)decyl-3-hydroxy-2-(hydroxymethyl)-2-methylpropanoate,and N,N-diethyl-ethanamine(triethylamine).Moreover,the influence of ultraviolet and visible(UV-Vis)light irradiation on the viscoelasticity of azo-containing WPU film in terms of the reversible trans-cis photoisomerization of azo-containing pendant groups was investigated by UV-Vis light spectroscopy,atomic force microscopy,and dynamic thermomechanical analysis.The results revealed that the adhesion of azo-containing WPU with single crystal silicon atomic force microscope probe was about 13 n N when irradiated by 450 nm Vis light for 60 s at 25°C.Subsequently,the adhesion increased to 82 n N after irradiation with 365 nm UV light for 60 s at 25°C.In addition,the azo-containing WPU presented a photo-induced reversible transition of tensile modulus and tanδin the range from about 2 MPa to 22 MPa and 6000 to 0.35 with UV-Vis light cyclic irradiation for 120 s at 25°C,respectively.展开更多
基金financially supported by the Guangzhou Science and Technology Plan Project (No. 201607010348)
文摘In this study,a novel waterborne polyurethane(WPU)with azobenzene-containing(azo-containing)pendant groups was synthesized by isophorone diisocyanate,long-chain diol of polycaprolactone,2-ethyl-2-methyl-butanoic acid(2,2-dimethylolpropionic acid),10-(4-(phenyldiazenyl)phenoxy)decyl-3-hydroxy-2-(hydroxymethyl)-2-methylpropanoate,and N,N-diethyl-ethanamine(triethylamine).Moreover,the influence of ultraviolet and visible(UV-Vis)light irradiation on the viscoelasticity of azo-containing WPU film in terms of the reversible trans-cis photoisomerization of azo-containing pendant groups was investigated by UV-Vis light spectroscopy,atomic force microscopy,and dynamic thermomechanical analysis.The results revealed that the adhesion of azo-containing WPU with single crystal silicon atomic force microscope probe was about 13 n N when irradiated by 450 nm Vis light for 60 s at 25°C.Subsequently,the adhesion increased to 82 n N after irradiation with 365 nm UV light for 60 s at 25°C.In addition,the azo-containing WPU presented a photo-induced reversible transition of tensile modulus and tanδin the range from about 2 MPa to 22 MPa and 6000 to 0.35 with UV-Vis light cyclic irradiation for 120 s at 25°C,respectively.
