PREPARATION OF PARTICULATE MONOLALYERS AND MULTILAYERS FROM SURFACTANT-STABILIZED, NANOSIZED MAGNETITE CRYSTALLITES

The preparation of particulate films and Langmuir-Blodgett (LB) films from lauric acid-stabilized, ca. 130 Angstrom diameter magnetite (Fe3O4) particles is described. A hexane solution of surfactant-stabilzed magnetite colloids was dispersed on a water subphase in a Langmuir film balance, and the structure of the resultant film was investigated by a range of techniques as a function of compression. Electron microscopic investigation of the particulate film demonstrated that compression resulted in the production of circular domains of magnetite particles in a lauric acid matrix and ultimately to a close-packed array of magnetite crystallites. The domains appeared to consist of a monoparticulate layer of crystals, with some aggregation occurring at higher compressions. Reflectivity measurements were consistent with this hypothesis, showing the film thickness at collapse to be 138 Angstrom, The films could subsequently be transferred to a solid substrate using the LB technique.