Enhanced chain densities of n-alkanethiolate self-assembled monolayers on gold from aqueous micellar solutions

This Letter reports that n-alkanethiolate self-assembled monolayers (SAMs) formed onto gold from aqueous micellar solutions of hexaethylene glycol mon ododecyl ether (C12E6) exhibit greater overall chain densities and are more electrochemically blocking than those formed from traditional organic solv ents such as ethanol. As determined by reflectance infrared spectroscopy, t he alkyl chains in SAMs formed from 10 mM C12E6(aq) are less canted on aver age than those in SAMs formed from ethanol. This greater overall chain dens ity for the water-borne SAMs is attributed to hydrophobic interactions betw een alkyl chains during assembly. Consistent with a more defect-free struct ure, the water-borne SAMs exhibit greater resistances against the diffusion of redox probes than SAMs formed in ethanol.