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Macromolecular Rapid Communications, Vol.28, No.7, 894-899, 2007
A novel benzoxazole-containing poly(N-isopropylacrylamide) copolymer as a multifunctional sensing material
We report a novel multifunctional material, poly(N-isopropylacrylamide) (PNIPAAm) containing 2-(2-hydroxyphenyl)benzoxazole (HPBO), for sensing pH, zinc ion concentration, or temperature. By titration with zinc ions, a clear blue-shifted emission with a high quantum efficiency was detected since the zinc complex prevented the nonradiative decay pathways of the HPBO moiety. The fluorescence characteristics of the copolymer were similar at various acidic or neutral conditions. However, a large blue shift on the emission maximum was exhibited under the basic condition, due to the disruption of the ESIPT process by the phenolate anion. The LCST affected the fluorescence properties significantly at the basic condition because the incompatibility between the PNIPAAm chain and phenolated HPBO moieties resulted in aggregation formation. The present study demonstrates that the new benzoxazole-containing PINPAAm copolymer could be potentially used as multifunctional sensing material.