Synthesis, characterization and reinforcing properties of novel, reactive clay/poly(glycidyl methacrylate) nanocomposites

Abstract Clay/polymer nanocomposites, of the type montmorillonite/poly(glycidyl methacrylate) [MMT/PGMA], were synthesized via atom transfer radical polymerization (ATRP). An ATRP initiator, consisting of quaternary ammonium salt bearing a 2-bromo-2-methyl propionate moiety was intercalated into the interlayer spacings of the layered silicate. The ammonium salt-modified montmorillonite (MMT–Br) served as macroinitiator for the in situ ATRP of glycidyl methacrylate resulting in highly exfoliated MMT/PGMA nanocomposites, as judged by XRD measurements. However, TEM shows the existence of intercalated clay regions, but at a very low extent. TGA and XPS analyses indicate that the nanocomposites have PGMA-rich bulk and surface. Indeed, the mass loading of PGMA reached 61 wt.% whilst XPS spectra, particularly the high resolution C1s region, resemble those of pure PGMA. The MMT/PGMA nanocomposites were found to be soluble in chloroform with a transparent solution, fully compatible with epoxy resin without any sign of phase separation. The primary MMT/PGMA nanocomposites were mixed with DGEBA and DETA in chloroform in order to prepare moulded, ternary MMT/PGMA–epoxy–DETA nanocomposites by solvent evaporation. The dried ternary systems exhibited superior viscoelastic properties (storage modulus and tan  δ ) compared to the neat crosslinked epoxy–DETA adhesive prepared in the absence of any clay nanocomposite.