Soluble PEG600-imidazole derivatives as the thermal latent catalysts for epoxy-phenolic resins

A series of novel soluble PEG600-imidazole compounds were synthesized and investigated as thermal latent catalysts for curing diglycidyl ether of bisphenol A (DGEBA). Based on the results of thermal latency and storage stability, the PEG600-imidazole catalyst showed better thermal latency than unmodified imidazole compounds. The glass transition temperature (Tg) results showed novel PEG600-imidazole catalyst provided complete or near complete curing systems in the temperature range about 150–159 °C. Following the data of the cure activation energy and the viscosity-storage time, the order of thermally latent activity was estimated PEG600-5-(hydroxymethyl)-imidazole (8) > PEG600-4-methylimidazole (6) > PEG600-imidazole (5) > PEG600-1-(2-hydroxyethyl)-imidazole (7) > 4-methylimidazole (4MZ, 2) > 5-(hydroxymethyl)-Imidazole (4) > 1-(2-hydroxyethyl)-imidazole (3) > imidazole (1).