PHASE-TRANSITIONS IN A LIPID BILAYER EMBEDDED IN A CRYSTALLINE MATRIX

The hydrocarbon part of (C10H21NH3)Cd2Cl4 represents a smectic lipid bilayer exhibiting two structural phase transitions in analogy to biomembranes. Single-crystal C13 NMR and N14 nuclear quadrupole resonance and x-ray data show that the first transition is connected with a disordering of the polar heads whereas the second represents a partial melting of the lipid chains. A Landau theory describing the melting of bilayer membranes in terms of order parameters used in the theory of liquid crystals has been constructed to explain the obtained results. © 1979 The American Physical Society.