Embodiments of the present disclosure are directed to heterogeneous advanced epoxy resins formed by reacting a mononuclear aromatic diglycidyl ether and a diphenol, more specifically, embodiments of the present disclosure are directed to heterogeneous advanced epoxy resins formed by reacting the mononuclear aromatic diglycidyl ether and the diphenol in a molar ratio of the mononuclear aromatic diglycidyl ether to the diphenol in a range from 1.5 to 1.0 to 5.0 to 1.0.