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Dispersion of graphene in a polymer matrix as mono layers is an important step towards fabricating high performance polymer-graphene nanocomposites. In this paper, a novel method based on Pickering emulsion polymerization has been introduced that assures fine dispersion and enhances loading. The major idea is to use a high affinity of graphene oxide (GO) for assembly at the liquidliquid interface for Pickering emulsion polymerization. A guideline for ensuring stable hybrid colloids of polymer-graphene oxide with an appropriate polymer particle size has been introduced. Then a system of poly (methyl methacrylate) (PMMA)-GO has been selected and the nanocomposites have been made by Pickering emulsion polymerization to examine the theory. TEM studies of the products show various interesting arrangements of PMMA and GO for a different size ratio of nanolayers to polymer particles. The new method paves the way for an environmentally benign process for the production of high quality polymer graphene nanocomposites as it is water-based (no organic solvent is employed) and soap free. Furthermore, resulting hybrid particles were melt mixed with PMMA as a master batch. The resulting nanocomposites with 0.3 wt% graphene showed improved thermal stability and stiffness.

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Response surface method of experimental design was applied to optimize the mechanical properties of polypropylene (PP)/nanoclay/CaCO 3 hybrid ternary nanocomposite using three different levels of melt flow index (MFI) of PP, nanoclay, and CaCO 3 contents. The samples were prepared by melt mixing in a lab scale corotating twin screw extruder. The main effect of each parameter on the tensile modulus, tensile strength, and impact strength was extensively discussed. The structure of obtained nanocomposite was studied using X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy (SEM) techniques. Tensile modulus and impact resistance of prepared ternary nanocomposite were correlated to considered parameters using a second-order polynomial model. Also, the optimum values of studied variables were determined using contour plots. The obtained results show that increasing the nanoclay and CaCO 3 contents improve the tensile modulus up to 45%, whereas the optimum value of impact strength, about 54%, is achieved at low concentrations of nanoclay (2 wt %) and CaCO 3 (8 wt %).