Alkanethiols possessing terminal phenyl groups (C6H5(CH2)nSH, n ) 12-15) were adsorbed onto the surface of gold to afford phenyl-terminated self-assembled monolayers (SAMs). The SAMs were characterized by optical ellipsometry, polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), atomic force microscopy (AFM), and contact angle goniometry. The films generated from the phenylterminated alkanethiols exhibited greater thicknesses but similar crystallinities and well-ordered lattice structures when compared to analogous SAMs generated by the adsorption of normal alkanethiols onto gold. Advancing contact angle measurements using water as the test liquid supported the presence of interfacial phenyl moieties. Furthermore, contact angle measurements using the test liquids methylene iodide (MI), dimethyl formamide (DMF), and nitrobenzene (NB) revealed an odd-even effect as a function of the number of methylene units underneath the terminal phenyl groups. The tribological properties of the phenyl-terminated films were characterized by AFM and compared to those of films derived from normal alkanethiols and other materials presenting aromatic hydrocarbon moieties at the interface (i.e., graphite and C60). The phenyl-terminated SAMs exhibited a substantially higher frictional response than graphite, a slightly higher frictional response than normal alkanethiol SAMs, but a much lower frictional response than C60-terminated SAMs.

We report the formation and subsequent topochemical polymerization of semi-fluorinated self-assembled monolayers (SAMs) containing diacetylene groups. The SAMs used were formed via the adsorption of the following derivatives: CF3(CF2)n(CH2)16CtCsCtC(CH2)10SH (n ) 2, 3) and CF3(CF2)n(CH2)11CtCsCt C(CH2)10SH (n ) 9, 12) onto the surface of gold. The polymerization of the monolayers was initiated by UV irradiation and was monitored using resonance Raman spectroscopy. SAMs with short semi-fluorinated portions were found to polymerize more effectively than those with longer portions, indicating that steric factors become important with increasing perfluorinated chain length.