Hydroxyterminated fluoroalkene oxide oligomers were reacted with chlorendic anhydride and subsequently with epsilon-caprolactone to produce carboxyterminated perfluoroethers prepolymers that were totally miscible with diglycidylether of bisphenol A. Curing the epoxy resin mixtures with hexahydrophthalic anhydride hardener and benzyl dimethylamine catalyst produced transparent products exhibiting a two-phase co-continuous morphology. Prereacting the fluoroalkeneoxide prepolymers with an excess of epoxy resin prior to the addition of hardener and catalyst, resulted in opaque products displaying a two-phase dispersed particles morphology. The dynamic mechanical spectra of the cured products confirmed the absence of any significant short-range network miscibility and revealed substantial enhancements in beta-relaxations in all cases, which are normally associated with microdispersed morphologies. Both systems exhibited much higher flexural strength and ductility than the equivalent unmodified epoxy resins, even at very low levels of addition, 3.5-5.0%. The surface energy was found to be much lower than that exhibited by the unmodified resin system, and the reduction in water absorption was relatively small. The above effects were much more pronounced for products exhibiting a particulate morphology than for systems that exhibited a co-continuous morphology.