MONOMERIC AND POLYMERIC MOLECULAR FILMS FROM THE DIETHYLENE GLYCOL DIAMINE PENTACOSADIYNOIC AMIDE

A new positively charged polymerizable single chain surfactant was synthesized and analyzed. Monomolecular films made from this surfactant were investigated. Their physical characteristics were evaluated using standard film balance techniques and studied as a function of the subphase pH. The pK of these films was determined to be 6.8 +/- 0.5. At room temperature these films exhibit a pronounced fluid/solid coexistence with a transition enthalpy of 35 +/- 3 kJ/mol for high subphase pH values. A strong rate dependent hysteresis between compression and expansion was found. The crystal morphology of the solid domains was investigated by microfluorescence at the air-water interface. Although the molecules themselves are achiral, the solid domains exhibit a distinct chirality. After UV polymerization the solid domains showed an intense intrinsic fluorescence due to the polymer backbone. Polymeric monomolecular films were transferred onto silicon oxide by standard Langmuir-Blodgett techniques. The structural properties of these films were investigated using the atomic force microscope. At intermediate magnifications the films appeared rippled; at high magnifications molecular resolution was obtained.