Multilayer Langmuir-Blodgett assemblies of hydrophobized CdS nanoparticlesby organization at the air-water interface

The formation of multilayer Langmuir-Blodgett (LB) films of hydrophobized C dS nanoparticles by organization at the air-water interface is described. T he hydrophobization of CdS nanoparticles (60 Angstrom diameter) synthesized in an aqueous medium is accomplished by extraction of the particles from s olution into thermally evaporated octadecylamine (ODA) films. Vigorous stir ring of the ODA-CdS nanocomposite films in organic solvents resulted in dis persion of the CdS particles in the organic phase. The hydrophobic CdS nano particles were dispersed on the surface of water, organized into a fairly c losely packed monolayer and multilayer films formed on different substrates by the versatile Langmuir-Blodgett technique. The organization of the part icles and formation of multilayer films by the Langmuir-Blodgett technique was followed by surface pressure-area isotherm measurements of the nanopart icle Langmuir monolayer, quartz crystal microgravimetry, contact angle meas urements, UV-vis spectroscopy and Fourier transform infrared spectroscopy s tudies. It is observed that a reasonably close-packed monolayer of the CdS nanoparticles forms on the surface of water and that excellent multilayer f ilms of the particles can be grown on different supports via sequential tra nsfer by the LB technique.