Color Indicator for Supramolecular Polymer Chemistry: Phenolphthalein-Containing Thermo- and pH-Sensitive N-(Isopropyl)acrylamide Copolymers and -Cyclodextrin Complexation

The copolymerization parameters of N-(isopropyl)acrylamide (1) and N-(2-hydroxy-5-(1-(4-hydroxyphenyl)-3-oxo-1,3-dihydroisobenzofuran-1-yl)benzyl)acrylamide (2) are determined. For both monomers, the homoaddition proceeds slightly faster than the heteroaddition step; however, the polymer formation occurs in a statistic fashion. Copolymers of different compositions are prepared and the cloud points are determined. Thereby, a significant influence of the concentration of monomer 2 and the pH value is found. For the first time, the complexation of polymer attached phenolphthalein by -cyclodextrins is shown. Furthermore, it is possible to achieve a decomplexation by the addition of suitable guest molecules. Both procedures can be followed with the naked eye.