A monolith
bonding system has a high reliability for dissimilar
material bonding. The epoxy monolith layer fabricated on a substrate
guarantees bond strength by the anchor effect, regardless of the compatibility
of the used materials. Designing a high-performance monolith bonding
system requires the suppression of an interfacial failure between
the monolith and the substrate. In this study, silane and phosphine
coupling agents containing amino and epoxy groups were used to construct
a robust interfacial structure between the monolith and the substrates
such as glass and metals. The internal and interfacial monolith structures
were characterized by three-dimensional X-ray imaging as a nondestructive
observation method in addition to the scanning electron microscopy
of the sample cross sections. The modification of the substrate–monolith interface using the coupling agents improved the strength of dissimilar
material bonding of the glass and metal substrates in combination
with thermoplastic resins such as poly(ethylene terephthalate) and
polycarbonate bisphenol-A.