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Thermally stable elastomeric composites were prepared via melt processing from poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) (SEBS) and conducting polymer‐modified carbon black (CPMCB) additives. CPMCB additives represent a novel thermally stable conductive compound made via “in‐situ” deposition of polyaniline or polypyrrole on carbon black particles. Incorporating CPMCB is advantageous to the melt processing of composites, as it reduces the melt viscosity in comparison to the use of pure carbon black. Thermogravimetric analyses (TGA) showed that the composites are thermally stable with no appreciable degradation at temperatures as high as 300°C. In addition, the electrical conductivity of the composites was found to be very stable at high temperatures. Polym. Compos. 25:617–621, 2004. © 2004 Society of Plastics Engineers.

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A taper-shaped phosphonic acid, 3,4,5-tris (dodecyloxy)phenylmethylphosphonic acid (1), was synthesized; its lyotropic liquid crystalline (LLC) behaviour and its ability simultaneously to order and acid-dope polyaniline were examined. It was found that the ability of 1 to form LLC phases in the presence of several hydrophilic solvents is restricted by strong intermolecular interactions between the phosphonic acid head groups (presumably H-bonding). The amphiphile exhibits poor miscibility with pure water and even with strong H-bonding organic solvents such as DMF. However, it forms a lamellar mesophase in the presence of aqueous acid. Upon deprotonation of the phosphonic acid head group with NaOH, the resulting disodium salt of the amphiphile is able to form a well de ned lamellar phase with pure water. The propensity of 1 to form lamellar phases is somewhat unusual since its tapered molecular shape should direct it to form an inverted hexagonal LLC phase. These results suggest that intermolecular head group interactions are more important in determining the overall LLC behaviour of this phosphonic acid amphiphile than are the hydrophobic character and shape of the organic tail system. Compound 1 was also found to be su Y ciently acidic to act as an acid dopant for the conjugated polymer polyaniline in the emeraldine base form. LLC acid 1 induces the resulting polymeric salt to form an electrically conductive LLC complex with an extended lamellar microstructure. The bulk conductivity of the resulting nanostructured polyaniline salt was found to be only in the semiconducting regime (10 Õ 5 S cm Õ 1 ), due to an unfavourable polyaniline chain conformation in the LLC complex.

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