A mixture of epoxidized soybean oil (ESO), (R)-12-hydroxystrearic acid (HSA) and a photoinitiator for cationic polymerization in the ESO/HSA weight ratio 10/1 was heated to 100 degrees C and gradually cooled to room temperature to give biobased gelatinous material. The photo-curing of the gel afforded a nanocomposite composed of crosslinked ESO and supramolecular HSA nanofibers. The transmission electron microscopy observation of the photo-cured ESO/HSA revealed that dendritic clusters of HSA nanofibers are formed in the crosslinked ESO matrix. In the differential scanning calorimetry chart of the ESO/HSA, a thermal transition from the mesophase composed of supramolecular nanofibers to isotropic state was observed at 67 degrees C (Delta H = 22.6 J/g-HSA), while the T-m of crystalline HSA is 77.7 degrees C (Delta H-m = 159 J/g-HSA). Tensile strength at 20 degrees C of the ESO-HSA was similar to 80% higher than that of photo-cured ESO without HSA. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 669-673, 2009