Novel Method for High-Spatial-Resolution Chemical Analysis of Buried Polymer-Metal Interface: Atomic Force Microscopy-Infrared (AFM-IR) Spectroscopy with Low-Angle Microtomy

Abstract

There is a great need for the analysis of the chemical composition, structure, functional groups and interactions at polymer–metal interfaces in terms of adhesion, corrosion, and insulation. Although atomic-force-microscopy-based infrared spectroscopy (AFM-IR) can provides chemical analysis with nanoscale spatial resolution, it generally requires to thin a sample to be placed on a substrate that has low absorption of infrared light and high thermal conductivity, which is often difficult for samples that contain hard materials like metals. This study demonstrates that the combination of AFM-IR with low-angle microtomy (LAM) sample-preparation can analyze buried polymer–metal interfaces with higher spatial resolution than that with the conventional sample-preparation of a thick vertical cross-section. In the LAM of a polymer layer on a metal substrate, the polymer layer is tapered to be thin in the vicinity of the interface, and thus, sample thinning is not required. An interface between an epoxyacrylate layer and copper wire in a flexible printed circuit cable was measured using this method. A carboxylate interphase layer with a thickness of ~130 nm was clearly visualized at the interface, and its spectrum was obtained without any signal contamination from the neighboring epoxyacrylate, which was difficult to achieve on a thick vertical cross-section. The combination of AFM-IR with LAM is a simple and useful method for high-spatial-resolution chemical analysis of buried polymer–metal interfaces.

In Situ Analysis of Local Strain Distribution of Amorphous Polyrotaxane Adhesives Constrained by Metal Substrates

“…However, the analysis of adhesive structures buried between substrates, which shield X-ray and electron beams, presents considerable challenges. These buried interfaces can be exposed to the surface via ultralow-angle microtomy, enabling the application of conventional surface analysis methods to reveal structures at certain moments during the fracture process. − Conversely, for nondestructive analysis, recent advancements in interface-sensitive analyses have been notable. Sum frequency generation vibrational spectroscopy, for instance, has revealed specific molecular orientations of buried polymers at the surface of transparent inorganic substrates .…”

Decoration of Ultramicrotome-Cut Polymers with Silver Nanoparticles: Effect of Post-Deposition Laser Treatment

“…The microtome is an original mechanical instrument that serves to prepare very thin cuts of biological samples for microscopic examination [5]. However, it has been used effectively to cut, for example, botanical specimens [6] and newly developed polymers [7]. Microtome cuts in the preparation of botanical specimens refer to various parts of botanical tissues, very small sections of wood [5] and plants [6], which serve for histological and pathological studies.…”

“…Such histological sections were suitable for wound care. The study of polymer-metal interfaces was performed by microtome cutting in the work of Baden et al [7]. In this case, the thin microtome cut of the sample increased the spatial resolution of the atomic force microscopy-based infrared spectroscopy technique.…”