Physicochemical Properties of Monolayers of a Gemini Surfactant with a Minimal-Length Spacer.

Fundamental physical chemical properties of monolayers formed from a new anionic gemini surfactant with a minimal-length (single-bond) spacer unit have been investigated at the air-water interface and compared with those of monolayers formed from affiliated comparator surfactants. The minimal spacer surfactant, dubbed C-0-C, exhibited strikingly different packing characteristics from an anionic gemini surfactant with a comparatively bulkier headgroup, including the formation of close-packed, crystalline films, and shared similar characteristics to simple fatty acid-based monolayers. Monolayers of C-0-C also exhibited good stability at the air-water interface and transferred with reasonable efficiency to solid substrates, although the film integrity was compromised during the transfer.

Single-Molecule Fluorescence Spectroscopy of Phase-Separated 10,12-Pentacosadynoic Acid Films.

Phase-separated monolayers of 10,12-pentacosadiynoic acid and perfluorotetradecanoic acid can be photopolymerized to produce micrometer-sized, fluorescent polydiacetylene fibers at the air-solid interface. The photopolymer fibers were not uniformly fluorescent but rather showed a series of fluorescent spots along their lengths. The spots exhibited the classic properties of single-molecule fluorescence emission, including diffraction-limited size and fluorescence intermittency ("on-off blinking").