Preparation of nanocomposites by in situ polymerization of sodium chloroacetylaminohexanoate in the presence of C20A or C30B organo-modified montmorillonites was studied. Both clays rendered an intercalated structure that contrasts with the exfoliated structure previously found with the use of the C25A montmorillonite. Polymerization under non-isothermal and isothermal conditions was evaluated by WAXD synchrotron radiation and FTIR experiments. Results indicate that C20A and C30B had a similar influence on the polymerization kinetics. Thus, the activation energy and the Arrhenius preexponential factor decreased compared to those calculated for the neat monomer. Clear differences were also found when using the C25A clay since, in this case, polymerization had similar activation energy to that determined for the neat monomer. The crystallization kinetics of the intercalated C20A and C30B nanocomposites was studied by FTIR and optical microscopy. The incorporation of clay particles increased the overall rate kinetic constant due to the enhancement of the primary nucleation. On the contrary, the spherulitic growth rate was slightly disfavored by the clay. Negative spherulites were always observed but the textures (speckled, ringed or fibrilar) depended on the crystallization temperature and incorporation of clay particles.