The novel mechanism of exfoliation of silicate was investigated. Exfoliation and intercalation was achieved even at 15 wt % in the polyurethane (PU) matrix via in situ polymerization. Through using IR consumption graph of curing agent, crosslinking equation could be derived. The diffusion rate of curing agent, Isophorone diisocyanate, brought the different morphologies as well as crosslinking densities of nanocomposites. Dodecylamine, the organifier having similar hydrogen-bonding component with Isophorone diisocyanate than octadecylamine, affected the faster diffusion of isophorone diisocyanate in hydroxyl terminated polybutadiene/organoclay composite. This phenomenon was confirmed by DSC graph, XRD, SAXS, and TEM images. The nanocomposites showed high physical properties until at 10 wt % clay. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013