Interfacial characterization of epoxy/silica nanocomposites measured by fluorescence

Abstract

Fluorescence labeling was used as a tool for the interfacial characterization of nanocomposites. The solvatochromic probe dansyl chloride was employed as interfacial reporter in epoxy/silica nanocomposites. Molecular spacers (organosiloxanes and polyetheramines) of different lengths were used to vary the location of the chromophore at the interface. The steady state and time resolved fluorescent responses reflect a rigid polar interface. Fluorescence changes during heating at a constant rate were analyzed for determining the local glass transition (Tg) at the interface region. The fluorescence results were then compared to the Tg obtained from differential scanning calorimetry and the results showed the existence of a gradient interface of a few nanometers thick having different properties than the bulk matrix. The thickness of this interface is small but its altered dynamics due to strong interactions with the nanofiller spreads its influence throughout the whole matrix.