The novel exfoliated polymer nanocomposites (PMMA/MgFe(DS)-LDH) were synthesized by in situ polymerization based on poly(methyl methacrylate) (PMMA) and dodecyl sulfate-intercalated MgFe-layered double hydroxide (MgFe(DS)-LDH).The nanostructures were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM)

the PMMA/LDH nanocomposites were partially interacted and partially exfoliated.The thermal degradation mechanism was discussed by thermogravimetric analysis (TG) and Tg.The participation of Fe3+ ion is found to play an important role in the improvement of thermal stability of nanocomposites with small inorganic loading and well-dispersed inorganic components.The thermal degradation temperature of the nanocomposites was 37～69 K higher than that of pure PMMA at 50% weight loss， and the exfoliated nanocomposite containing 1.6 wt% inorganics had the best thermal stability.All nanocomposites have excellent transparency on the visible range due to molecular level dispersion of inorganic nanolayer

the transparence of nanocomposite containing 8.0 wt% inorganics in the visible range was almost over 90%.This sufficient dispersion was very helpful and important to the improvement in properties.The DSC showed that the Tg of the nanocomposite containing 8.0 wt% inorganics was about 34.7 K higher than that of the pristine PMMA.The increment in Tg is probably a result of the polymer-filler interactions that restrict the polymer-chain mobility.These findings demonstrated that using effective molecules and rational synthesis of nanocomposites were suitable for subsequent novel nanocomposites synthesis.