title: Self-assembled monolayers derived from a double-chained monothiol having chemically dissimilar chains.
abstract: The structure and conformation of self-assembled monolayers (SAMs) derived from the adsorption of a specifically designed double-chained partially fluorinated thiol having the formula 12,12,13,13,14,14,15,15,16,16,17,17,18,18,19,19,19-heptadecafluoro-2-tetradecylnona-decane-1-thiol (2) onto the surface of evaporated gold were examined by ellipsometry, contact angle goniometry, polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS), and X-ray photoelectron spectroscopy (XPS). The results were compared to those of SAMs generated from normal hexadecanethiol (1) and a structurally related single-chained partially fluorinated thiol having the formula 12,12,13,13,14,14,15,15,16,16,17,17,18,18,19,19,19-heptadecafluorononadecane-1-thiol ( 3). Collectively, the studies demonstrate that the double-chained adsorbate 2 forms SAMs on gold in which the alkyl chains are less densely packed and less conformationally ordered than those in the SAMs derived from each of the single-chained adsorbates. Furthermore, the fluorocarbon moieties in the SAMs derived from 2 are more tilted from the surface normal than those in the SAMs derived from 3. The low values of contact angle hysteresis suggest, however, that the double-chained adsorbate 2 generates homogeneous monolayer films on the surface of gold.
authors.affiliation: Departments of Chemistry and Chemical Engineering, University of Houston, Houston, TX 77204-5003, USA.
authors.forename: Shishan
authors.initials: S
authors.lastname: Zhang
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Jamison
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Schwartz
authors.forename: T Randall
authors.initials: TR
authors.lastname: Lee