A Lattice Statistical Thermodynamic Study of Bilayer Amphiphile Molecules

In order to elucidate conformational properties of bilayer semiflexible amphiphile molecules, we derive a expression of free energy separation with respect to bilayer width, and segment density profiles on the basis of cubic lattice model. Our result shows that at the moderate surface coverage region (i.e., ${\sigma}$ < 0.35), bilayer system tends to have thermodynamically favorable bilayer width corresponding to free energy minimum condition resulting from the major contribution of attractive interaction between chain segments. However such a favorable bilayer width do not occur in the region of high surface converage (i.e., ${\sigma}$> 0.4) where repulsive interaction between chain segments is considered to be dominant.