Effects of alcohols on membranes of water/surfactant/alcohol ternary systems. A solid state deuterium NMR study

In this paper, we investigate the effects of alcohol on the structure and dynamics of water/SDS/alcohol Lα phases, using 2H-NMR of deuterium-labelled surfactant. From measurements of quadrupolar splittings, orientational order parameters for the entire bilayer are determined and allow to calculate, through an appropriate model, the hydrophobic thickness, δh, of the membrane. It is shown that changing the octanol-to-surfactant ratio does not modify δh whereas increasing the alcohol chain length leads to a bilayer thickness increase. A comparison is made between 2H-NMR results and small angles X-rays diffraction (SAX) measurements