Using a localized fluorescent dye to probe the glass/resin interphase

A novel technique has been developed to study the buried polymer/substrate interfacial regions by localizing a fluorescent probe on the substrate surface. Epoxy functional multi‐layers of silane coupling agents were deposited on glass and doped with small amounts of a fluorescently labeled silane‐coupling agent (FLSCA). When the dye‐doped silane layers were immersed in an epoxy/amine cured resin, a blue shift in the emission maximum was measured after resin cure. Silane layers of varying thickness were tested. Thicker layers showed smaller fluorescence shifts during cure, suggesting incomplete resin penetration into these layers. The fluorescence sensitivity to the interfacial reaction was verified with external reflection Fourier Transform Infrared Spectroscopy (FTIR) of the silane layers immersed only in the amine hardener.