Hybrid organic-inorganic nanocomposites: Exfoliation of magadiite nanolayers in an elastomeric epoxy polymer

A newly developed class of paraffm-like organomagadiite intercalates, interlayered by primary, secondary, tertiary, and quaternary onium ions, has been used to form elastomeric polymer-layered silicate nanocomposites by in situ polymerization during the thermoset process. Depending on the nature of the onium ions, intercalated or exfoliated magadiite nanocomposites were obtained. The exfoliated nanocomposites were typically disordered, but a new type of exfoliated structure also was observed in which the nanolayers were regularly spaced over long distances (e.g., similar to 80 Angstrom Bragg spacings). The tensile properties of the polymer matrix were improved greatly by the reinforcement effect of the silicate nanolayers. Exfoliated silicate nanolayers were more effective than intercalated assemblies of nanolayers in optimizing reinforcement, Interestingly, organomagadiite exfoliation in the rubbery epoxy matrix improves the elongation-at-break while improving tensile strength, which is opposite to the behavior of conventional composites. The tensile properties of the new epoxy-magadiite elastomeric nanocomposites are compared with those for previously reported nanocomposites derived from smectite clays.