Two bio-based epoxy prepolymers were synthesized from isosorbide, a carbohydrate-based C6 building block, using two different synthetic routes. The chemical structures of the bio-based epoxy prepolymers were analyzed by SEC, ESI-TOF MS, FTIR, (1)H NMR and (13)C NMR analysis. The resulting epoxy prepolymers differ by the molar mass distribution, one consists of the pure epoxy monomer whereas the other exhibits various oligomeric species. A traditional petroleum-based epoxy prepolymer, DGEBA, which has similar epoxy equivalent weight, was also used in this study for comparison. Gelation and crosslinking reactions of the two bio-based epoxy precursors with an amino hardener, isophorone diamine, were studied using rheological measurements and differential scanning calorimetry (DSC) respectively; the effect of the stoichiometric ratio n(ah)/n(e) was investigated. Structures of the epoxy networks were evaluated using dynamic mechanical analysis (DMA) and thermo gravimetric analysis (TGA). (C) 2011 Elsevier Ltd. All rights reserved.