Successive Phase Transitions in Lipid Membranes

On the basis of a statistical model previously proposed by the present authors, a new sort of phase transition recently observed in the fluid-like phase of DPL bilayer and mono-layer above the main transition temperature is investigated as successive orientational transitions accompanied with conformational changes. The effects of lateral pressure on the transition temperatures and latent entropies observed in DPL monolayer are also explained consistently. This type of phase transition is expected to occur in DML, DSL and DBL as well, although it has not been observed yet in the case of these molecules.