STRUCTURE AND CHARACTERIZATION OF SURFACTANT-CAPPED CDS NANOPARTICLE FILMS BY THE LANGMUIR-BLODGETT TECHNIQUE

Oligomer-polymaleic acid octadecanol esters (PMAO) with different rati os between carboxylic groups and hydrocarbon chains stabilized CdS nan oparticles were produced in the form of reversed micelles. The PMAO-ca pped CdS nanoparticles were transferred from the air-water interface o nto CaF2 and silicon substrates. Surface pressure-area isotherms gave the information that both the two kinds of pure PMAO and PMAO-capped C dS could form stable monolayers on the water subphase. From the area o ccupied by average molecular unit (0.24 and 0.11 nm(2)), it was conclu ded that the size of two kinds of PMAO-capped CdS nanoparticles was di fferent. The results of UV-vis spectra gave us information that the di ameter of CdS nanoparticles could be controlled to less than 2 nm. The measurement of Fourier transform infrared spectroscopy (FTIR) confirm ed the formation of CdS. The average tilt angle of hydrocarbon chains revealed by polarized IR spectra was 50 and 60 degrees, respectively. The long spacing of the multilayer of PMAO-capped CdS determined by sm all angle X-ray diffraction was 6.3 and 4.8 nm, which also maintained the conclusion that the ratio between carboxylic groups and hydrocarbo n chains effect the size of reversed micelles. (C) 1998 Elsevier Scien ce S.A. All rights reserved.