Microspheres of polyurethanes functionalized with push-pull type azo chromophores and their photoinduced deformation behavior

Publication date: 24 February 2017
Source:Polymer, Volume 111
Author(s): Yuqi Zhou, Bingyang Liu, Xiaogong Wang
A series of azo polyurethanes bearing push-pull type azo chromophores was synthesized by post-polymerization azo-coupling reactions between a polyurethane precursor and diazonium salts of different aniline derivatives, respectively. Colloidal spheres with narrow size distributions were obtained by aggregation of these azo polyurethanes in DMF-H2O mixed solvents, which were induced by slowly increasing the water content. The self-assembling processes and formed structures were investigated by laser light scattering and transmission electron microscopy. When irradiated with linearly polarized light from Ar⁺ laser (488 nm) and diode solid state laser (532 nm), the azo polyurethane microspheres showed significant deformations elongated in the light polarization direction. The electron-withdrawing groups on the azo chromophores show a significant effect on the photoinduced deformation degree. These microspheres composed of the azo polyurethanes bearing carboxylic acid and trifluoromethyl groups as the electron-withdrawing substituents shows the largest deformation degrees when irradiated with 488 and 532 nm light, respectively.

Graphical abstract

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