Synthesis and properties of difunctional cycloaliphatic epoxides

Three novel cycloaliphatic difunctional epoxides containing symmetric or asymmetric epoxycyclohexyl moieties linked with an ether bond or with a carbon-carbon bond, 3, 4-epoxycyclohexylmethyl-2′, 3′-epoxycyclohexyl ether (I e), bis(2, 3-epoxycyclohexyl) ether ( IIe), and di(2, 3-epoxycyclohexane) (III e), were synthesized by epoxidation of their corresponding dicycloolefin, respectively. Their precursor compounds, 3-cyclohexene-1-methyl-2-′-cyclohexene ether (I), bis(2-cyclohexenyl) ether (II), and di(2-cyclohexane) (III) were also prepared. The structure of the three epoxides and cycloolefins was confirmed by infrared spectroscopy (IR), elemental analysis (EA), and ¹H-NMR spectroscopy. To evaluate the thermal properties of the cycloaliphatic epoxy compounds, a commercial bicycloaliphatic epoxy, 3, 4-epoxycyclohexylmethyl 3′, 4′-epoxycyclohexane carboxylate( marked name ERL-4221) was used for comparison. Three epoxides and ERL-4221 were cured with HMPA, and thermal properties of the cured polymers were examined by thermomechanical analysis, differential scanning calorimetry, and dynamic mechanical analysis. The cured polymers obtained from epoxy I e, II e and III e showed higher glass transition temperature, higher storage modulus, and lower coefficient of thermal expansion than those of ERL-4221.