MOLECULAR-ORGANIZATION OF PHOTOREACTIVE UNSATURATED CARBOXYLATES ON LANGMUIR-BLODGETT-FILM

The surface pressure-area (pi-A) isotherms of dioctadecyldimethylammon ium chloride (2C(18)DAC) and dioctadecyldimethylammonium cinnamate (2C (18)DA.Cin) were measured, and their time dependence was examined. The surfaces of Langmuir-Blodgett films of 2C(18)DAC and 2C(18)DA.Cin wer e observed by atomic force microscopy. The effect and location of cinn amate anions against molecular organization on Langmuir monolayers of 2C(18)DA are discussed. After preparation, cinnamate ions bind on the hydrophilic surface of the 2C(18)DA monolayer, by forming ion pairs wi th 2C(18)DA cations and by directing aromatic groups toward the interi or of the aqueous subphase. When the Langmuir film is maintained for l ong periods at a constant surface pressure, cinnamate ions are interca lated into the monolayer, as aromatic groups penetrate into the hydrop hobic interior of the monolayer. (C) 1998 Academic Press.