Self-assembled monolayers on polymer surfaces: Kinetics, functionalization, and photopatterning

Monolayers of bifunctional bolaamphiphiles were self-assembled on a polymer ic substrate (spin-coated film of poly(allylamine hydrochloride)). Various features of the novel bifunctional, well-ordered, and relatively stiff mono layer and the subsequent reactions of the exposed benzoyl azide groups were investigated. The characterization of the monolayers and the kinetics of s elf-assembly was determined via reflection-absorption infrared spectroscopy and ellipsometry. Atomic force microscopy and ellipsometry were used to me asure roughness and thickness, respectively. From molecular modeling and el lipsometry, the bolaaphiphiles in the monolayers were found to be inclined at an angle of about 68 degrees to the normal. In addition, the monomolecul ar layers appeared to be fairly crystalline. Serial functionalization of th e exposed benzoyl azide groups with dansyl-cadaverine in the liquid phase f ollowed by propylamine in the gas phase illustrated a stable, dense, well-o rdered, two-dimensional monomolecular layer of bolaamphiphiles. Photopatter ning, via UV irradiation of exposed benzoyl azide groups, was also demonstr ated. The novelty of the surface modification procedure described here is t he extraordinary ease with which self-assembly took. place and the stabilit y of the resulting monolayers which formed a highly reactive new surface su itable for further modification. Arranging molecules in a tidy ordered arra y on a polymeric surface is a main result of this work.