Formation of Langmuir−Blodgett Films of a Clay and a Water-Soluble Alkylammonium Cation

Abstract

We have studied the formation of ultrathin hybrid films composed of a water-soluble alkylammonium cation (trimethyloctadecylammonium caiton: TMODAH+) and clay nanosheets at an air-water interface. When a chloroform solution of the ammonium salt of TMODAH+Cl- was spread onto a surface of an aqueous clay suspension in a Langmuir trough, a stable monolayer of the water-soluble ammonium cation was formed by hybridization with the clay nanosheets at the air-water interface. Surface pressure--molecular area (pi-A) isotherm curve of the hybrid monolayer shifted to the smaller molecular area side with the increase in the concentration of the ammonium salt in the solution or with the decrease in that of the clay in the suspension. In some cases, the lift-off areas in the pi-A isotherm curves were less than the cross-sectional area of an alkyl chain (ca. 0.19 nm2). These results indicated that some ammonium cations spread onto the clay suspension were dissolved into the aqueous subphase before the hybridization with the clay nanosheets. The hybrid monolayers were transferred onto a glass plate in a layer-by-layer way by horizontal dipping to form a hybrid multilayerd film. Interestingly, the densities of TMODAH+ determined by the infrared spectral analysis were constant in the hybrid multilayers prepared from the clay suspensions at the same concentration, regardless of the concentrations of the ammonium salt solutions. XRD patterns of the films showed that the cations of TMODAH+ would lie down on the clay layer in the hybrid film.

Temperature and concentration dependence of J-aggregate of a cyanine dye in a Laponite film fabricated by Langmuir–Blodgett technique

“…Here the initial liftoff area shifts toward larger area per molecule with the increase in the Laponite concentration, typical for organo-clay hybrid Langmuir films (Umemura and Shinohara, 2005). The NK isotherm in presence of Laponite show distinct liquidexpanded phase before collapse.…”

Oxygen Sensing by the Hybrid Langmuir-Blodgett Films of Iridium(III) Complexes and Synthetic Saponite on the Basis of Energy Transfer

“…The basic principle is that a floating film of amphiphilic cationic molecules at an air-water interface is hybridized with clay particles (denoted as a clay nanosheet) exfoliated in an aqueous dispersion. The optimum conditions for preparing a clay hybrid film of high quality were studied extensively [8,9]. The surface morphology and layered structures of a deposited film were investigated by means of various spectroscopic methods [10].…”

“…Recently, the hybridization of amphiphilic cations with clay minerals were attempted to prepare an LB film in order to overcome the disadvantage of fragileness [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Clay minerals are layered inorganic compounds.…”

Photoelectrocatalytic oxidation of GMP on an ITO electrode modified with clay/[Ru(phen)2(dC18bpy)]2+ hybrid film

“…The LB method involves the spreading of cationic surfactants at the air-water interface over a diluted clay suspension. The negatively charged clay particles are adsorbed electrostatically onto the cationic parts of floating amphiphilic molecules [10][11][12] . The hybrid films produced are transferred onto the surface of a conductive substrate.…”