Insights into the structure and dynamics at the hexadecane droplet–water interface in the presence of 1-alkanols as emulsifiers: Molecular dynamics studies

Abstract

The structure and dynamics at the surface of nanoscopic hexadecane droplets immersed in aqueous phase with and without emulsifiers (1-alkanols of varying chain length; pentanol, heptanol, decanol and dodecanol) have been studied using atomistic molecular dynamics simulations. The nature of layering of alcohol molecules on the oil droplet is governed by the hydrophobicity of alkanols. Longer chain alkanols are more likely to penetrate into the oil droplet. The probability of tangential orientation of hexadecane molecules at the interface decreases with decreasing hydrophobic environment around the droplet. The interfacial hexadecane molecules show greater probability to obtain a puckered conformation in binary oil–water system than in ternary oil–water–alkanol systems. Decrease in hydrophobic interaction between hexadecane and water molecules due to the efficient screening of oil surface by longer chain alkanols in ternary oil–water–alkanol systems leads to greater survival probability of water molecules in the oil–water interfacial layer and enhancement in life time of H-bonds formed between alcohol and water molecules.