Modeling the properties of self-assembled monolayers terminated by carboxylic acids

Self-assembled monolayers of long-chain carboxylic acids are often used as substrates to promote the growth of oriented crystals. Recent work has shown that the length of the chain (odd or even number of carbon atoms) determines whether oriented growth is observed. We use molecular dynamics simulations to investigate whether the configuration of the headgroups is significantly different in the two cases. We conclude that there are differences between odd- and even-length chains, even at 300 K and in the presence of water for some packings of the monolayer. We discuss whether these differences are large enough to account for the different behavior.