Figure 5.

Photo images of POFs (containing 10 wt % benzophenone, 1 h UV irradiation of pattern) immersed in different media: (a) air (dried POFs), (b) water, and different mixtures of EtOH and H₂O, with (c) 20%, (d) 40%, (e) 60%, (f) 80%, (g) 100% of EtOH by volume fraction. Scale bar is 0.5 cm. Blue and red spots in part g show detection regions for the reflection spectra. (h) Wavelength of the reflection peak from irradiated (blue line) and nonirradiated (red line) regions when immersed in mixture of EtOH and H₂O with different volume fractions. (i, j) Reflection spectra of (i) nonirradiated regions and (j) irradiated regions after the POFs were immersed in different media.