Well-ordered self-assembled monolayers created via vapor-phase reactions on a monolayer template

The reaction of vapor-phase alkyl isocyanates (O=C=N-(CH2)(n-1)CH3) with OH-terminated alkanethiol template monolayers on Au produces well-organized self-assembled monolayers, containing intrachain carbamate linkages (Au/S(CH2)(16)O(C=O)NH(CH2)(n-1)CH3, where n = 1-8, 11, and 12). X-ray photoelectron spectroscopy, contact angle goniometry, and reflection absorption infrared spectroscopy suggest that the template surface completely reacts with the isocyanates yielding a monolayer that contains an interchain hydrogen-bonded carbamate network. Spectroscopic data indicates that the alkyl underlayer remains well ordered following reaction with the isocyanates. The order of the overlayer and the hydrogen-bonding interactions between adjacent chains increase as a function of the alkyl isocyanate chain length, n. The overlayer appears to be well ordered for n greater than or equal to 5.