Conventional epoxy resins exhibit excellent mechanical strength and chemical resistance but often suffer from high brittleness and limited elongation due to rigid crosslinked networks. In this study, epoxy resins were designed as the primary network structure, incorporating ethylene glycol derived chains to enhance chain mobility and deformability. Linear diisocyanates form flexible segments, while ether linkages from ethylene glycol promote segmental motion in the cured network. This molecular design enables epoxy thermosets with improved elongation while maintaining structural integrity. Thermal, mechanical, and rheological properties were evaluated using DSC, DMA, and rheological analysis. In addition, ether linkages provide potential pathways for chemical degradation, suggesting applicability to flexible and recyclable epoxy systems.