The ternary system
didodecyltrimethylammonium bromide,
1-decanol,
and water forms an extended reversed continuous phase of cubic symmetry
at 25 °C. The cubic phase belongs to the space groupIm3m, as shown by small-angle X-ray experiments.
We present extensive deuterium NMR relaxation data from this cubic
phase for 1-decanol, deuterated at the carbon adjacent to the hydroxyl
carbon position.2H spin-lattice (R1) and spin–spin (R2) relaxation
rates were measured over the existence region of the cubic phase,
which extends from 0.2 to 0.6 in volume fraction of the dividing bilayer
surface of the cubic phase. The data are interpreted with an existing
theoretical framework for NMR spin relaxation in bicontinuous cubic
phases, which takes its starting point in the description of bicontinuous
phases using periodic minimal surfaces. Specifically, we obtain the
self-diffusion coefficient over the minimal surface in one unit cell
for 1-decanol. We also present pulsed field gradient NMR-derived self-diffusion
data for didodecyltrimethylammonium bromide and compare the two sets
of data. The diffusion data for both components show a mild, if any,
dependence on the volume fraction of the bilayer surface. Furthermore,
we present diffusion data for the water component in the cubic phase.
Finally, we discuss the influences of the choice of the value of the
product of the deuterium quadrupole constant and the order parameterS. Within the framework of the model used to analyze the
relaxation data, a value for this parameter is required. As an initial
value, we rely on measurements of deuterium quadrupolar splittings
from deuterated decanol in an anisotropic phase.