Hydration of poly(N-isopropylacrylamide) brushes on micro-silica beads measured by a fluorescent probe

Hydration of poly(N-isopropylacrylamide) brushes on silica micro-beads was investigated using a fluorescent probe method. The free ends, the bottom, and the random of brushes were labeled with dansyl group. The emission spectra at the thin brushes were reduced with increasing temperature regardless of their labeling locations. At the free ends of thick brushes, the emission intensity was enhanced at 500 nm and reduced at 455 nm by heating, which was corresponding to the local micro-environmental change around the free ends. The spectral shift was speculated to be due to the enhancement of the flexibility and the hydration of thick brushes. (C) 2010 Elsevier B. V. All rights reserved.