Manipulation of interfacial amine density in epoxy-amine systems as studied by near-edge X-ray absorption fine structure (NEXAFS).

In this work, we investigate the ability to tune the quantity of surface amine functional groups in the interfacial region of epoxy-diamine composites using NEXAFS, a technique that is extremely sensitive to surface composition. Thereby, we employ a model surface (silicon wafer with the native oxide present) and, after deposition of an epoxy functionalized silane, we immersed the wafers in various diamines, followed by reaction with a diepoxy acting as a molecular probe. These results show that the number of available surface amines depends on the diamine chosen, wherein smaller molecular weight diamines provide more reaction sites.