A SIMULATION STUDY OF FLEXIBLE ZWITTERIONIC MONOLAYERS - EFFECTS OF SOLVENCY AND SPACER MOLECULES

We consider the numerical simulation of two opposing layers of zwitter ion molecules. We address two contributions of the solvent: (1) change s in the dielectric screening of the electrostatic interaction between the zwitterions and (2) the long-range interaction of hydrated molecu les. Further, we study a system of mixed monolayers, zwitterions/neutr al spacer molecules. This work stems from experimental conditions whic h are argued to limit the validity of the entropic fluctuation contrib ution considered responsible for the repulsion between phospholipid bi layers. We find that these factors do not place the above mechanism in doubt. We explain one specific experimental finding, and we place our model into context with the appropriate experimental situation.