Effect on thermo‐mechanical properties by in‐situ emulsion polymerization of polymer/clay nanocomposites

Bentonite clay nanoparticles without surface modification were used to prepare a polymer‐based nanocomposite: Butyl acrylate (BA), methyl methacrylate (MMA), and acrylic acid (AA) were copolymerized as the matrix. The synthesis was carried out using seeded batch emulsion polymerization system. Bentonite was added up to 3 wt% and the metastable emulsions remained for a period over 6 months in storage at room temperature, to estimate the emulsion stability. Cast films were obtained from the aqueous dispersions and these were optically transparent. Scanning electron microscopy and X‐ray scattering spectra showed that the copolymer chain had intercalated the Bentonite nanoplatelets, with aggregates into small crystalline clusters and dispersed through the polymer matrix. Differential scanning calorimetry showed that increasing the concentration of Bentonite increased the glass transition temperature, T_g. Furthermore, uniaxial tensile deformation at room temperature showed that the elastic Young's modulus, E, increased over an order of magnitude at 3 wt% Bentonite concentration. These results suggest that the molecular dynamics is inhibited, due to the associated restricted motions of the confined macromolecules within the gallery clay and the increment of the molecular weight. POLYM. COMPOS., 40:263–276, 2019. © 2017 Society of Plastics Engineers