A cationic macromonomer, 2-methacryloylethylhexadecyldimethylammonium bromide MA16, and a cationic macroinitiator, cationic acrylic/styrene oligomer end-capped with a nitroxide, were used to modify pristine Na−MMT, to enhance compatibility between the clay platelets and the host acrylic polymer matrix in waterborne nanocomposites. Both cationic species were successfully exchanged in the montmorillonite. The organically modified clays were used for the synthesis of acrylic (MMA/BA)/clay waterborne nanocomposites by miniemulsion polymerization. The 30% solids containing latexes were stable and coagulum free and presented better mechanical, thermal and barrier properties than the pristine acrylic copolymer.

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Summary: Waterborne polymer clay nanocomposites (WPCN) were prepared by emulsion and miniemulsion copolymerization of butyl acrylate and methyl methacrylate with enhanced mechanical, thermal and barrier properties for coating applications. Emulsion polymerization was used to synthesize WPCN using pristine Na‐MMT (sodium montmorillonite) and miniemulsion polymerization to prepare the WPCNs when the pristine clay was organically modified and hence its incorporation into the polymerization loci was not guaranteed by the conventional emulsion polymerization technique. Both techniques allowed preparing stable nanocomposite latexes of BA/MMA copolymers with partially exfoliated morphologies as demonstrated by wide X‐ray difraction (WAXD) and transmission electron microscope (TEM) measurements. Furthermore, latexes with solids contents up to 45 wt% and manageable viscosities were prepared for the first time using seeded semibatch emulsion polymerization.