Degradable epoxy resins prepared from diepoxide monomer with dynamic covalent disulfide linkage

Development of a methodology for designing network polymers with both structural rigidity and facile degradability is an important challenge. In this paper, we demonstrate the efficient degradation of epoxy resins with disulfide linkages synthesized from bis(4-glycidyloxyphenyl)disulfide and several diamines. The synthesis was carried out without any undesired side-reactions derived from disulfide bonds, as supported by the structural characterization of the model linear polymer. While tensile testing revealed that the obtained resins possess comparable mechanical properties to the reference resin without disulfide bonds, they degraded into completely soluble fragments on a time-scale of several tens of minutes via disulfide exchange reaction in the presence of base. On the other hand, the resin containing disulfide bonds only at the diamine moieties only partially degraded and remained undissolved under the same conditions, which indicates that the design for fragmenting into smaller molecules is effective for the degradation of epoxy resins with dynamic disulfide linkages.