Epoxy resin bearing diacylhydrazine moiety as a degradable adhesive for traceless oxidative removal

- Bisphenol bearing a CONHNHCO moiety and ester groups cured epoxy resin.
- The cured resin was strong, tough, and thermally stable adhesive for glass and metal.
- The cured resin was degraded easily without any trace by NaClO solution.
- Bonded materials were separated spontaneously on the treatment with NaClO solution.

Bisphenols functionalized with diacylhydrazine moieties and ester groups were prepared from 5-hydroxyisophthalic acid by esterification and partial hydrazination, followed by oxidative coupling of the obtained hydrazide. Ester groups with long alkyl chains or polyether increased the solubility of bisphenols in the epoxy resin. The epoxy resin was cured by heating with bisphenols in the presence of a catalytic amount of imidazole, with more rapid curing observed for more soluble bisphenols. The cured resin, with Td5 ≈ 300 °C, decomposed rapidly when exposed to sodium hypochlorite solution. The above resin could be used as a strong and tough adhesive for metal and glass, whereas it can be easily removed by treatment with sodium hypochlorite solution without any trace. The observed dismantling rate positively correlated with bisphenol solubility.

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