Polymeric nanocomposites based on an epoxy cycloaliphatic resin and o-montmorillonite (Cloisite 30B(R)) modified by reaction with maleinized liquid polybutadienes were prepared through photopolymerization. The conditions for the o-montmorillonite modification were settled. After the reaction. a strong, increase of the basal spacing of the nanoclays was evidenced through XRD analysis. The modified clays were dispersed in the epoxy resin (5 wt.%) and subjected to the UV-curing process. The kinetics of the photopolymerization process was evaluated by means of Real-Time FT-IR spectroscopy. The obtained nanocomposites were studied by means of XRD and TEM analyses; the formation of either intercalated or quasi-exfoliated structure was assessed. The thermal and mechanical properties of the cured films were evaluated and correlated to the morphology of the obtained nanocomposites. (C) 2007 Elsevier Ltd. All rights reserved.