Epoxy Infiltration into Nanoporous Aluminum Oxide

This research uses spatially-resolved electron energy-loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) to study epoxy infiltration into a nanoporous aluminum surface oxide. Imaging by scanning electron microscopy (SEM) shows that the oxide surface of an as-anodized aluminum wire consists of columnar nanopores with diameters ranging from approximately 5 -150 nm. Anodized wires were embedded in a 100 g: 28 g mixture of DGEBA (diglycidyl ether of bisphenol-A) resin and PACM20 (bis(p-aminocyclohexyl)methane) curing agent followed by a two-step cure. Electron-transparent sections were cut by ultramicrotomy. Spatially-resolved carbon and oxygen EELS profiles from the oxide are anti-correlated indicating that oxide pore walls are separated by pore interiors containing epoxy. Spatially-resolved low-loss spectral data are transformed into a measure of apparent specimen thickness. Comparisons of such data with simulations based on experimentally derived oxide topologies indicate that the pores are fully filled.