In previous work we have discovered the upper critical solution temperature (UCST) behavior of poly(methyl methacrylate) in ethanol-water solvent mixtures, which was found to be tunable by incorporation of a small fraction of more hydrophilic or hydrophobic comonomers.1-3 In the current work, a series of azobenzene containing copolymers were synthesized by post-modification of poly(methyl methacrylate)-co-(pentafluorophenyl methacrylate) with an amine-functionalized azobenzene. Light- and thermo-responsive behavior of these copolymers in ethanol-water solvent mixture was investigated with various content of ethanol. The UCST of the polymer solutions could be highly tuned by the substitution degree of the copolymers and the ethanol content of the solvent mixture. Light responsiveness of copolymers was also achieved due to the isomerization of azobenzene group under UV irradiation. Furthermore, the UV responsiveness is highly influenced by the composition of the solvent, i.e. a higher decrease of cloud point induced by UV-irradiation was found in ethanol-water solvent mixture with higher content of water. To the best of our knoledege, this is the first example of combining light responsiveness with UCST behavior for polymers in aqueous solutions. 1 R. Hoogenboom, S. Rogers, A. Can et.al., Chem. Commun., 2009, 5582.2 R. Hoogenboom, C. R. Becer, C. Guerrero-Sanchez, S. Hoeppener and U. S. Schubert, Aust. J. Chem. 2010, 63 , 1173.3 Q. Zhang, P. Schattling, P. Theato and R. Hoogenboom, Polym. Chem., 2012, 3 , 1418.

UV-tunable upper critical solution temperature behavior of azobenzene containing poly(methyl methacrylate) in aqueous ethanol solutions

248th National Meeting (2014)

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