We investigated a chemically modified rhodamine B dye as a sensor of local water content in dye-modified epoxy resins, where these measurements were combined with dielectric measurements to estimate the dye–water association ratio in the material. In particular, the water-sensitive fluorogenic dye was covalently attached to the epoxy resin backbone. This dye becomes fluorescent only upon photoactivation by ultraviolet light and its protonation in the presence of water. High-resolution noncontact microwave cavity dielectric measurements on these materials indicate a decrease of the dielectric permittivity upon photoactivation. We utilize this effect to determine the average extent of hydration of the activated dye molecules. Our results suggest that fluorogenic dyes are promising for the quantification of the local water content in polymer materials, such as the technologically important problem of interfacial water in epoxy materials.

中文翻译：

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通过非接触微波介电谱法定量环氧树脂中的荧光染料水合。

我们研究了一种化学修饰的若丹明B染料作为染料改性环氧树脂中局部水含量的传感器，其中将这些测量值与电介质测量值结合在一起以估计材料中的染料与水的缔合比。特别地，将水敏感性荧光染料共价附接到环氧树脂主链。该染料仅在通过紫外线进行光活化时以及在水存在下的质子化时才变为荧光。在这些材料上的高分辨率非接触微波腔介电常数测量表明，光激活后介电常数降低。我们利用这种效应来确定活化染料分子的平均水合程度。