Poly(methyl acrylate-co-methyl methacrylate) [P(MA-co-MMA)] nanocomposite film containing 1 wt % of montmorillonite (MMT) exhibited unusual higher ductility, higher strain recovery ratio after creep, and higher modulus and strength compared to neat P(MA-co-MMA) as they were cast from their individual latices fabricated by soap-free emulsion polymerization. The fortified mechanical properties were attributed to the MgO components of exfoliated MMT nanoplatelets being grafted by P(MA-co-MMA) chains as verified by FTIR and XPS spectroscopies, which to the best of our knowledge is the first time in the literature providing the direct evidence for the polymer chains grafting onto the exfoliated MMT. TEM investigation of the stretched nanocomposite film revealed that the microcracks in the nanocomposite film appeared mainly in the bulk region of polymer matrix, implying that the interfacial strength between P(MA-co-MMA) and its grafted MMT nanoplatelets was higher than the cohesion strength of P(MA-co-MMA). (c) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5891-5897, 2009