Nanocomposites of conducting polyaniline (PAN) with inorganic Na + -montmorillonite (MMT) clay were synthesized by the emulsion polymerization method. The dodecylbenzenesulfonic acid (DBSA) was used for both dopant and emulsifier. Analyses of X-ray diffraction patterns demonstrated that conducting PAN-DBSA was intercalated between inorganic clay layers at the nanoscale level (<10 Å). We observed that the clay induced more disordered state in PAN-DBSA/clay nanocomposites. From the temperature-dependent dc conductivity [σ dc(T)] experiments, we investigated charge transport mechanism of the PAN-DBSA and PAN-DBSA/clay systems. The interaction between the intercalated PAN-DBSA and the clay layers was observed by FT-IR spectra. The results of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed the improved thermal stability of the nanocomposite materials. The σ dc of these systems was 10 1 -10 -2 S/cm at room temperature, varying with dopant molar ratio. The σdc(T) of the nanocomposite of PAN-DBSA/clay was represented by the quasi-one-dimensional variable range hopping model. From electron paramagnetic resonance experiments, magnetic susceptibility was obtained for the systems. We discuss the effects of the intercalation and clay on charge transport, structural, and thermal properties for PAN-DBSA/clay nanocomposites.

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The sharp and broad electron spin resonance ͑ESR͒ signals from nanocomposites of conducting polypyrrole ͑PPy͒ with inorganic Na ϩ-montmorillonite ͑MMT͒ clay were simultaneously observed. The decomposed linewidths (⌬H P-P) of the sharp and broad ESR peaks of the nanocomposites at room temperature were 0.44 G and 21 G, respectively. However, we observed one broad ⌬H P-P (ϳ12 G) for the conducting PPy without the Na ϩ-MMT clay. From the analyses of the observed ESR signals, we propose that the narrow ⌬H P-P originates from the weak spin-orbit interaction of the intercalated nanolayers of the nanocomposites, while the broad ⌬H P-P originates from the bulky conducting PPy on the outside of the clay particles. The thermogravimetric and differential scanning calorimeter results showed that intercalation in the nanocomposites induced the thermal stability. Coulomb interactions between the positively charged polymers of the intercalated nanolayers and the negatively charged surface of the clay play an important role in the sharp ESR signal and the enhanced thermal stability.