Formation of surface molecular macroclusuters and fabrication of polymer nano-film: Dependence on surface density of hydrogen-bonded functional groups

We have demonstrated that ethanol macroclusters of ca. 5-6 nm in thickness are formed on gold substrates modified with mercapto compounds bearing hydrogen-bonding functional groups, namely, OH and COOH groups. This study aims at examining the effect of the surface density of hydrogen-bonding groups on the ethanol adsorption layer. We modified gold substrates with SAMs of 11-mercaptoundecanol and n-octylmercaptan mixtures. With increasing the surface density of the COOH groups, the change values of SPR effective angle at 1.8 mo% ethanol relative to the cyclohexane, |Δθ_eff(1.8)|, increase from 0.03° at 0 % surface density to 0.46° at 100 %. By utilizing this phenomenon, we can change the thickness of the ethanol adsorption layer by changing the surface density of hydrogen-bonding groups. In addition, we report the formation of the polyacrylic acid nano-film on the gold surface modified with the mercapto compound bearing OH and COOH groups.