Studies of Structure and Molecular Distribution in Lyotropic Ribbon Aggregates

Abstract

A lyotropic phase consisting of elongated ribbon aggregates on a rectangular lattice is formed with a ternary mixture of potassium palmitate (KP), potassium laurate (KL) and water. Deuterium NMR and x-ray studies of molecular factors which affect the formation of the aggregate system are reviewed. By selective deuteration of the lipids 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 aggregate. The shape of the ribbon and molecular ordering within the ribbon are also reviewed.