Measurements of the conductivity and relaxation times for the micellar nematic phase of the system ammonium perfluorononanoate/H2O

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Abstract
Measurements of the electric conductivity for two mixtures of ammonium perfluorononanoate and H2O are presented. The molar ratios for the two mixtures are 0.0159 (sample S2) and 0.0112 (sample S3). The mixtures show a nematic (NL) range about 8 °C wide, between a lamellar smectic and an isotropic micellar solution. The conduction is predominantly due to the NH4+ ions, and it is estimated that about 50% of the NH+4 ions have free mobility. At the same reduced temperature in the NL phase, the lower concentration mixture is more anisotropic, indicating larger micelles for the lower concentration. The reorientation of the director of the NL phase in a magnetic field is also measured. Near the NL to isotropic transition the relaxation times at 10 kG are 30 s for S2 and 80 s for S3. The divergence behavior of the relaxation times at the NL to lamellar transition is different for the two samples. Also, at corresponding temperatures, the relaxation time for the lower concentration is longer than the high concentration mixture. It is also observed that in the lamellar phase, increasing the temperature may lead to undulation of the layers.