NMR study of the slow dynamics and local structure in lyotropic micellar liquid crystals

RAMIRO RODRIGUEZ; FABIAN VACA CHAVEZ; DANIEL PUSIOL; ANTONIO FIGUEIREDO NETO

Granular Matter

Springer Verlag

Año: 2001 vol. 3 p. 53 - 56

1434-5021

The first experimental evidence of director fluctuations in a micellar lyotropic liquid crystal, studied by 1H spin-lattice relaxation rate, is reported. The system is constituted by the ternary mixture: potassium laurate/1-decanol/water. With the aim to test the slow dynamics, the experiment has been performed over a broad range of Larmor frequencies (2 × 103 − 6.6 × 106 Hz), usingfast field-cyclingNMR relaxometry. The results evidence that in the nematic and isotropic mesophases and the poliphasyc region, director fluctuations are responsible for the spin-lattice relaxation dispersion in the low Larmor frequency range (105 Hz), two relaxation mechanisms are assigned: i) molecular reorientation by translational diffusion on the micellar surface, and ii) molecular exchange between the micelle and the bulk.