SYNOPSISNanocomposites are prepared by a simple technique of emulsion polymerization using MMA monomer and Na+-montmorillonite. The products are purified by hot toluene extraction and characterized by FT-IR, X-ray diffraction, TGA, DSC, and tensile testing. The structural investigation confirms that the products are intercalated with PMMA chain molecules oriented parallel to the direction of lamellar layers whose separation is consequently more enlarged than in the polymer-free clay. DSC traces also corroborate the confinement of the polymer in the inorganic layer by exhibiting no observable transition in the thermogram. Both the thermal stability and tensile properties of the products appear to be substantially enhanced. The ion-dipole bonding is believed to be the driving force for the introduction and fixation of the organic polymer to the interfaces of montmorillonite.

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This article demonstrates the direct intercalation of an epoxy polymer in the interlayer of Na / -montmorillonite (MMT) by a step type of polymerization in an aqueous emulsion media. The synthesis and the results of structural and thermal characterizations for this hybrid composite are described. Equimolar quantities of bisphenol A and an epoxy prepolymer ( n Å 0.2) in an emulsion media were polymerized in the presence of Na / -MMT. X-ray diffraction (XRD) data obtained from the acetoneextracted products show that the basal spacing of the MMT is expanded from 0.96 to 1.64 nm. Thermal characterization for the postcured products by TGA and DSC gave evidence of enhanced thermal stabilities. SEM examination of the uncured products revealed that a disordered phase begins to appear with increasing polymer loading. However, the XRD profile supported that an overwhelming fraction of the nanocomposite contains intercalated clay. Also, the possibility of intercalation by the emulsion technique is proposed on the basis of the swelling characteristics of MMT in aqueous media and the sizes of micelles containing a monomer.

A well-defined styrene-acrylonitrile copolymer/montmorillonite (SAN-MMT) nanocomposite has been prepared by emulsion copolymerization of styrene and acrylonitrile in the presence of sodium ion exchanged montmorillonite (Na ϩ -MMT). This direct and one-step polymerization technique yielded nanocomposites intercalated with styrene-acrylonitrile copolymer without occurrence of significant delamination of MMT. The purified products by hot tetrahydrofuran extraction for up to 5 days gave evidences of copolymer intercalation. Those infrared spectra obtained from the purified products revealed the characteristic absorbances due to styrene, acrylonitrile, and MMT. Room temperature powder X-ray diffraction patterns of the purified product exhibited increased 001 d-spacing about 1.60 nm. The transmission electron microscopy micrograph of unpurified products confirmed that the 1-2-nm sized silicate layers are arranged in good order. The onset temperature of purified products are found to be moved to higher temperature, while the thermograms of differential scanning calorimetry show nothing observable transition. The modulus of elasticity of the product was increased with increasing content of MMT, whereas the stress at maximum load was decreased with the increments of MMT.