Malleable and recyclable thermoset network with reversible β-hydroxyl esters and disulfide bonds

By combining bifunctional diglycidyl ether of bisphenol A (DGEBA) and trifunctional tris(4-hydroxyphenyl) methane triglycidyl ether (TMTE) epoxy monomers, along with 4,4′-dithiodibutyric acid (DTDBA) as a carboxylic acid, a variety of novel reprocessable and recyclable thermoset polymers are synthesized. The crosslinked network structures with different crosslinking densities are produced by changing the mixing ratio between DGEBA and TMTE, resulting in changes in mechanical and thermal properties of the final products. The stress relaxation and self-healing experiments confirmed that all of these polymeric materials have covalent adaptable networks in their microstructures and perform reversible transesterification processes inside a polymer network. These thermoset polymers are completely decomposed in solution by disulfide-thiol reduction of DTDBA with reversible cleavage or coupling capability in the presence of reducing agent, allowing chemical recycling capability into the thermoset polymer network.