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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 Youngs 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., 00:000-000, 2017. V C 2017 Society of Plastics Engineers FIG. 2. Solids analysis obtained as a function of polymerization time for (i) copolymer and the nanocomposites containing (a) 1 wt%, (b) 2 wt%, and (c) 3 wt% bentonite. Lines are only intended as guide to the eye. FIG. 3. Degree of conversion and coagulum amount of polymer/clay emulsions as a function of bentonite concentration. Lines are only intended as guide to the eye. FIG. 7. Photographs of copolymer/bentonite nanocomposites, about 1.0, 0.4, 0.2, and 0.5 mm in thickness, casted from their respective emulsions. The concentrations of bentonite are (a) 0 wt%, (b) 1 wt%, (c) 2 wt%, and (d) 3 wt%. FIG. 12. (a) TGA and (b) DTG curves for (i) copolymer and nanocomposites containing (ii) 1 wt%, (iii) 2 wt%, and (iv) 3 wt% of bentonite.

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Based on the nature of the links and interactions existing at the hybrid interface, hybrid materials can be broadly classified in two main designations: a) Hybrid compounds Class I, that include all systems with electrostatic forces, hydrogen bonding or Van der Waals interactions and b) Hybrid compounds Class II, showing that the inorganic and organic components are linked through strong covalent or ionic-covalent bonds. The physico–chemical properties of nanostructured copolymer acrylates based on butyl acrylate (BA), methyl methacrylate (MMA) and acrylic acid (AA) has been investigated employing un-modified SiO2 (Class I) and modified SiO2 particles (Class II) using 3-(trimethoxysilyl) propyl methacrylate (MPS) as compatibilizing agent. The synthesis was carried out using seeded batch emulsion polymerization system. Metastable nanostructured emulsions containing 1 wt% nanoparticles were obtained. Films casted from the in-situ nanostructured latex exhibited excellent optical transparency suggesting good nanoparticles dispersion. However, the mechanical properties showed by SiO2-MPS nanocomposite, are better than the Class I hybrid compounds. Therefore, SiO2-MPS surface treatment prior to polymerization enhances the physical properties of copolymer BA-MMA-AA film. The mass loss derivative traces for the polyacrylic nanocomposites and the neat polymer obtained by thermogravimetric analysis showed that the onset temperature for thermal decomposition was shifted towards a higher temperature than the neat polyacrylic, indicating the enhancement of thermal stability of the un-modified SiO2 nanocomposite. However, there is a decrease of 40°C in the decomposition temperature for the modified polyacrylic nanocomposite. The results obtained so far have shown that weak Van der Waals and H-bonding interactions may be sufficient to enable improvement of the physical properties of the acrylate nanocomposites.

The field of composites materials has evolved from the use of traditional fillers (e.g. carbon and glass fibers) to nanoscale fillers that add unique and often multifunctional properties to the neat polymer. Because nanoparticles have extremely high surface to volume ratios, that alter the mobility of polymer chains near their interfaces, even a small addition of nanoparticles. These components have the potential to drastically transform the properties of the host polymers. While the last decade has observed several advances in the field of nanocomposites, some recent reviews have made it clear that definitive structure-property relationships are insufficient in the literature. The influence of inorganic TiO2 nanoparticles on the dynamic mechanical properties and microstructure of copolymer based on Butyl acrylate - Methyl methacrylate - Acrylic Acid has been investigated. The mechanical relaxations of the reinforced copolymer/TiO2 composites were studied under tension mode. Addition of TiO2 nanoparticles to acrylic copolymer produced a decrease in the glass transition temperature. Dynamic mechanical analysis (DMA) showed that the local motions associated with the alpha-transition (40°C) are enhanced as the frequency of oscillation increases, i.e. the tan d maximum increases at higher frequencies. The addition of TiO2 nanoparticles reduces significantly the strength of the alpha-transition. Thus, the cooperative molecular motions involving segments of the molecular chains associated with the alpha-transition were compromised by the presence of TiO2 nanoparticles resulting in a decrement of the storage modulus.