Highly concentrated, intercalated silicate nanocomposites: Synthesis and characterization

PMMA-layered silicate intercalated nanocomposites are synthesized using supercritical carbon dioxide (scCO(2)) to produce ordered materials with significant levels of reinforcement. The scCO(2) is used to homogeneously distribute monomer as well as act as a low-viscosity solvent for MMA polymerization. This route allows for synthesis of nanocomposites containing significant levels of organically modified layered silicates (OMLS). Below 40 wt % OMLS, the intercalated nanocomposites exhibit a d spacing commensurate with dimensions of the fully extended surfactant chains. Above 40 wt % OMLS, the composite volume is saturated with inorganic material, and the d spacing decreases to homogeneously distribute the polymer volume. A model for estimating this transition concentration is presented. At concentrations approaching the homogeneously intercalated morphology, the basic mechanical and physical properties of the composite are investigated.