Molecular distribution among regions of different curvature in aggregates of a lyotropic ternary system: A NMR measurement

A lyotropic phase consisting of elongated ribbon aggregates on a rectangular lattice is induced when a small amount (∼1 mol %) of potassium laurate (KL) is added to a potassium palmitate (KP)/water mixture. By selective deuteration it is shown that the KL and KP molecules are not uniformly distributed throughout the ribbon aggregate. The less abundant KL molecules with the shorter hydrocarbon chain are more concentrated at the edges of the ribbons where there is high curvature, whereas the more abundant KP molecules are more concentrated in the central lamellar region of the aggregates. A quantitative measurement is described. The deuterium spectra also show how the KP and KL lipids are distributed among coexisting phases when an uneven distribution also occurs. The KP molecules prefer the lamellar structures, whereas the KL molecules prefer the aggregate structures. © 1985 American Institute of Physics.