Physical and chemical imaging of adhesive interfaces with soft X-rays

Hiroyuki Yamane,Masaki Oura,Osamu Takahashi,Tomoko Ishihara,Tetsuya Ishikawa,Koichi Hasegawa,Takaki Hatsui,Noriko Yamazaki,Kiyoka Takagi

doi:10.1038/s43246-021-00168-5

Hiroyuki Yamane, Masaki Oura + Show 7 more

Open Access

https://doi.org/10.1038/s43246-021-00168-5

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Abstract

Adhesion is an interfacial phenomenon that is critical for assembling carbon structural composites for next-generation aircraft and automobiles. However, there is limited understanding of adhesion on the molecular level because of the difficulty in revealing the individual bonding factors. Here, using soft X-ray spectromicroscopy we show the physical and chemical states of an adhesive interface composed of a thermosetting polymer of 4,4’-diaminodiphenylsulfone-cured bisphenol A diglycidyl ether adhered to a thermoplastic polymer of plasma-treated polyetheretherketone. We observe multiscale phenomena in the adhesion mechanisms, including sub-mm complex interface structure, sub-μm distribution of the functional groups, and molecular-level covalent-bond formation. These results provide a benchmark for further research to examine how physical and chemical states correlate with adhesion, and demonstrate that soft X-ray imaging is a promising approach for visualizing the physical and chemical states at adhesive interfaces from the sub-mm level to the molecular level.

Highlights

Adhesion is an interfacial phenomenon that is critical for assembling carbon structural composites for next-generation aircraft and automobiles
Steel/alloy-based vehicles have long been assembled using bolted joint and arc welding techniques. These conventional joining methods are not well-suited for carbon-fiber-reinforced plastics (CFRPs) because bolts increase weight, bolt holes reduce the stiffness of CFRPs, and arc welding does not work for joining polymer-based structures[2,3]
For soft X-ray imaging of the adhesive interface, a cross-section of the DGEBA-DDS/PEEK interface was magnified at the sample surface by oblique polishing (Fig. 1b)

Summary

Results and discussion

For soft X-ray imaging of the adhesive interface, a cross-section of the DGEBA-DDS/PEEK interface was magnified at the sample surface by oblique polishing (Fig. 1b). The exposed cross-section was introduced into a trifluoroacetic anhydride (TFAA) atmosphere, which can fluorinate the OH a c

F Kα c max

A B1B2 C 1

Conclusion

Methods