Dispersed molecular aggregates II.: Synthesis and characterization of nanoparticles of tungstic acid in H2O/(TX-100+alkanol)/n-heptane W/O microemulsion media

Colloidal dispersions of tungstic acid (H2WO4) have been prepared in water/(TX-100 + alkanol)/n-heptane water-in-oil microemulsion media by reacting Na2WO4 with HCl. The effects of alkanol chain length, TX-100/alkanol mass ratio, temperature, and dilution at different [water]/[TX-100] mole ratios (omega) have been studied by the dynamic light scattering technique. The formation of H2WO4 in the microwater pool has been established by FT-IR measurements. The particle sizes and shapes in microemulsion media and in isolated states have been measured by TEM and SEM techniques. The enthalpy of formation of H2WO4 in the water pool of the microemulsions has also been determined microcalorimetrically. (C) 2001 Academic Press.