title: Triphenylene silanes for direct surface anchoring in binary mixed self-assembled monolayers.
abstract: New triphenylene-based silanes 2-(ω-(chlorodimethylsilyl)-n-alkyl)-3,6,7,10,11-penta-m-alkoxytriphenylene 4 (Tm-Cn) with n = 8 or 9 and m = 7, 8, 9, 10, or 11 were synthesized, and their self-assembly behavior in the liquid state and at glass and silicon oxide surfaces was investigated. The mesomorphic properties of triphenylene silanes 4 (Tm-Cn) and their precursors 3 (Tm-Cn) were determined by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction. From the small-angle X-ray scattering (SAXS) regime, a preferential discotic lamellar mesophase can be deduced, and wide-angle X-ray scattering (WAXS) highlights the liquid-like characteristics of the alkyl side chains. To transfer these bulk structural properties to thin films, self-assembled monolayers (SAMs) were obtained by adsorption from solution and characterized by water contact angle measurements, null ellipsometry, and atomic force microscopy (AFM). Employing the concentration as an additional degree of freedom, binary SAMs of 2-(ω-(chlorodimethylsilyl)-undecyl)-3,6,7,10,11-penta-decyloxytriphenylene 4 (T10-C11) were coassembled with chlorodecyldimethylsilane or chlorodimethyloctadecylsilane, and their capability as model systems for organic templating was evaluated. The structure of the resulting binary mixed SAMs was analyzed by water contact angle measurements, null ellipsometry, and X-ray reflectivity (XRR) in combination with theoretical modeling by a multidimensional Parratt algorithm and AFM. The composition dependence of film thickness and roughness can be explained by a microscopic model including the steric hindrance of the respective molecular constituents.
authors.affiliation: Institut für Organische Chemie, Universität Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Mansueto
authors.forename: Sven
authors.initials: S
authors.lastname: Sauer
authors.forename: Martin
authors.initials: M
authors.lastname: Butschies
authors.forename: Martin
authors.initials: M
authors.lastname: Kaller
authors.forename: Angelika
authors.initials: A
authors.lastname: Baro
authors.forename: Rebecca
authors.initials: R
authors.lastname: Woerner
authors.forename: Nis Hauke
authors.initials: NH
authors.lastname: Hansen
authors.forename: Guenter
authors.initials: G
authors.lastname: Tovar
authors.forename: Jens
authors.initials: J
authors.lastname: Pflaum
authors.forename: Sabine
authors.initials: S
authors.lastname: Laschat