THE FORMATION DYNAMICS OF CHOLESTEROL FILMS PREPARED BY SPONTANEOUS SELF-ASSEMBLY METHOD

The dynamics of the process of formation of cholesterol films on a sol id substrate prepared by the spontaneous self-assembly technique has b een investigated. An expression for the coverage in a multilayer syste m was derived. Application of the equation to cholesterol multilayer h im formation kinetics shows that the approach to equilibrium of the se lf-assembly process obeys first-order rate law. An observed adsorption free energy change of -21..7 +/- 0.1 kJ mol(-1) was obtained for chol esterol on quartz slide and a mean lifetime of cholesterol on the slid e surface during deposition of 78 +/- 3 ks at 298.16 K. A mean lifetim e for stearic acid adsorbed from hexadecane onto native aluminium oxid e surface (data from elsewhere) was found to be 12.4 +/- 0.3 ks. The r esults suggest dynamic processes which strongly depend on the formatio n constant of the amphiphile for coordination to the substrate.