Role of a Surface Active Agent in the Sol-Emulsion-Gel Synthesis of Spherical Alumina Powders
Authors: Siladitya, B.; Chatterjee, M.; Ganguli, D.
Source: Journal of Sol-Gel Science and Technology, Volume 15, Number 3, September 1999 , pp. 271-277(7)
Abstract:Spheroidal alumina particles of tailor-made size were prepared by the sol-emulsion-gel method under simultaneous mechanical agitation and sonication and by systematic variation of the concentration of a non-ionic surfactant in the organic solvent (“oil phase”) above or below the critical micelle concentration (CMC). The CMC of the surfactant in the organic solvent of low dielectric constant was determined from discernible breaks in surface tension, viscosity, optical absorption and dye fluorescence vs. concentration curves. The CMC of the surfactant played an important role in controlling the sol droplet size and accordingly, the size of the alumina particles obtained therefrom. Transmission electron microscopy (TEM) revealed that near (but below) CMC the nanospheroids (10–50 m) were in the state of chain-like agglomerates. Beyond CMC, spheroidal particles of larger dimensions were obtained. Particle size analysis showed a sharp decrease in mean size with increasing concentration of the surfactant up to CMC, above which a gentle upward trend was noticed.
Document Type: Regular Paper
Affiliations: Sol-Gel Division, Central Glass & Ceramic Research Institute, Calcutta 700 032, India
Publication date: 1999-09-01