Structure–Property Relationships in Hydrolytically Degradable Epoxy–Amine Networks From Ester‐Bridged Diepoxides

ABSTRACT Ester groups influence intermolecular interactions and segmental mobility while introducing hydrolytically‐ or alcoholytically‐cleavable bonds. Here, a series of para‐substituted ester‐containing bisphenols is prepared from phenolic acids and short‐chain alcohols. The bisphenols are converted to ester‐bridged diepoxide monomers that were previously unreported or underexplored as thermoset building blocks. Resistance of the ester linkages to hydrolysis during diepoxide synthesis depends on ester density and precursor hydrophilicity. MTT cell proliferation assays indicate no significant estrogenic activity for most bisphenol precursors, although one aromatic ester bisphenol causes proliferation comparable to bisphenol A. The diepoxides are cured with isophorone diamine to form epoxy–amine networks. Variations in interphenylene bridge length, steric and electronic environment of the ester groups, and ester concentration tune glass‐transition temperatures from 80°C to 153°C and control degradability under alkaline conditions. Mass loss by alkaline hydrolysis ranges from less than 4% after 28 days for an aromatic monoester network to complete dissolution within 48 h for the most susceptible aliphatic diester network—reflecting ester concentration, network hydrophilicity, and local ester environment. Aromatic ester networks approach the tensile and compressive performance of a diglycidyl ether of bisphenol A reference, and all ester‐containing networks exhibit higher lap‐shear strength and pull‐off failure stress than the reference.