Poly(methyl methacrylate) (PMMA)/layered double hydroxides (LDH) nanocomposites were synthesized by in situ bulk polymerization. The LDHs were synthesized by coprecipitation method. Eight LDHs having different compositions were produced, varying the divalent/trivalent cations (Zn/Al, Mg/Fe), the ratio between these cations (2: 1 and 4: 1) and the LDH intercalated anions (dodecyl sulfate and laurate). The LDH percentage (wt %) in the PMMA was fixed at 1%. The thermal properties of the nanocomposites were evaluated by thermal analysis (thermogravimetricTGA and differential scanning calorimetryDSC). Most of the nanocomposites presented higher thermal resistance than PMMA and the best results were presented by the following nanocomposites: PMMA/(Zn/Al 2: 1 laurate) and PMMA/(Zn/Al 4: 1 laurate). The dynamic mechanical properties of the nanocomposites were investigated and compared to those obtained for PMMA. It was noticed that PMMA/(Mg/Fe 4: 1 laurate) nanocomposite presented an elastic modulus 2.2 times higher than PMMA at 40 degrees C. This investigation demonstrated that the addition of low concentrations of selected LDHs can enhance some desired properties of PMMA. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012