Poly(methyl Methacrylate)/Laponite Nanocomposites: Exploring Covalent and Ionic Clay Modifications
Polymers and High Performance Materials
Laponite clay was modified with combinations of organic ammonium surfactant and/or covalently bound poly( methyl methacrylate) ( PMMA). Two polymer attachment methods were explored, one through reaction of a methacrylate compound with the clay's silanol group followed by in situ free-radical polymerization of methyl methacrylate (MMA), and the other through attachment of an ATRP initiator followed by brush polymerization. The free-radical method yielded clays with ca. 75 wt % of polymer bound though multiple attachment sites to the clay, whereas the ATRP method yielded ca. 68 wt % of bound polymer attached only at the chain end. The PMMA-modified clays were very dispersible in organic solvents and were solvent-blended with commercial PMMA at 1, 3, 5, and 10 wt % concentrations. The resulting nanocomposites were optically transparent and homogeneous. TEM images showed mixed intercalated and exfoliated dispersions. DMA analysis showed an increase in room temperature modulus of 50% at 5 wt % concentration for the clay with no surfactant and PMMA free-radical attachment.
Chemistry of Materials
Wheeler, P. A.,
Mathias, L. J.
(2006). Poly(methyl Methacrylate)/Laponite Nanocomposites: Exploring Covalent and Ionic Clay Modifications. Chemistry of Materials, 18(17), 3937-3945.
Available at: http://aquila.usm.edu/fac_pubs/2290