Preparation and characterization of ultrathin layers of substituted oligo-and poly(p-phenylene)s and mixed layers with octadecanethiol on gold and copper

Substituted poly(p-phenylene)s were adsorbed from solution onto gold and co pper and oligo(p-phenylene)s onto gold. The layers were investigated with I R spectroscopy at grazing incidence reflection, XPS, NEXAFS, ToF-SIMS, surf ace profilometry, AFM, SEM, optical microscopy, ellipsometry, and contact a ngle measurements to examine their formation and structure. The structure a nd the properties of the investigated layers depend not only on the chemica l structure of the polymer but also on the type of substrate. On gold, the polymers form layers of 15-25 Angstrom in thickness and the oligomers of ca . 5 Angstrom in thickness. On copper, "thick" layers of up to 900 Angstrom were also observed. The oligomers have a lower affinity to gold than the po lymers. Mixed octadecanethiol-polymer layers were prepared by immersion of polymer-coated substrates in an octadecanethiol solution or by exposure of self-assembled monolayers of octadecanethiol to polymer solutions. The stru cture of the mixed layers depends on the sequence of the exposure of the tw o components and on the chemical structure of the polymer. In the mixed lay ers, structures that protrude above the surroundings were frequently detect ed at the surface.