²H NMR study on the lyomesophases of the system hexaethylene glycol dodecyl methyl ether/water Temperature dependence of quadrupole splittings

The liquid-crystalline phases of the system hexaethylene glycol n-dodecyl methyl ether (C12E6C1)/water are studied by deuteron NMR spectroscopy. Information about the molecular orientation is derived from the quadrupole splittings of two selectively deuteriated derivatives of C12E6C1, one deuteriated at the α-position of the alkyl chain, the other at the methoxy group. The temperature dependence of the quadrupole splittings reveals a continuous decrease of orientational order on approach to the macroscopic phase transformations. This behaviour is explained by an increase of defects and fluctuations in the microstructure of the mesophases.