Translucent acrylic nanocomposites containing anisotropic laminated nanoparticles derived from intercalated layered silicates

New acrylic nanocomposites consisting of methyl methacrylate (MMA)/n-dodecy lmethacrylate (LMA) copolymers and intercalated layered silicates were prep ared. The silicates were based upon bentonite which was rendered organophil ic by ion exchange with N,N,N,N,-dioctadecyl dimethyl ammonium ions. Morpho logical, thermal, mechanical, and optical properties were examined as a fun ction of both organophilic bentonite and LMA content. Addition of LMA impro ved the compatibility between the layered silicate and the acrylic matrix, thus promoting bentonite intercalation and formation of anisotropic laminat ed silicate nanoparticles of an average diameter of 18 nm, average length o f 450 nm, and interlayer distance of 4.8 nm, as determined by WAXS, TEM, an d AFM. Addition of 2-10 wt % of intercalated layered silicate accounted for improved stiffness/toughness balance, higher glass temperature, and enhanc ed thermal stability, with respect to the properties of the corresponding M MA/LMA copolymer. As a result of the addition of LMA, translucent acrylic n anocomposites were obtained. (C) 2000 John Wiley & Sons, Inc.