MOLECULAR DYNAMICS STUDY OF n -ALCOHOLS ADSORBED ON WATER

Molecular dynamics simulations of three types of normal alcohols (n-alcohols), n-propanol (C 3 H 7 OH), n-heptanol (C 7 H 1 5 OH), and n-undecanol (C 1 1 H 2 3 OH), adsorbed on water, were carried out as a function of the n-alcohol concentration. The simulation results reveal the following. The distribution of n-propanol on water is homogeneous at all concentrations studied here, and the distribution of n-heptanol and n-undecanol on water is heterogeneous. For n-heptanol, the steady adsorption layer appears discretely as the number of n-heptanol increases. When a monolayer or multilayer of n-heptanol is formed on water, the fluctuations of the water surface are small. But large fluctuations can be observed between these two concentrations. For n-undecanol, the n-undecanol molecules tend to cluster in a single region on the water surface below the concentration at which the monolayer of n-undecanol is formed These molecular dynamics simulations indicate the generation of fluctuations in the alcohol distribution on water that lead to heterogeneous distribution.