Dodecyltrimethylammonium bromide-styrene microemulsion dielectric investigation in aqueous media

Abstract

In this paper, we report the complex permittivity of aqueous microemulsions of N-dodecyltrimethylammonium bromide and styrene. The studies were carried out at 298.15 K while varying the styrene to surfactant concentration ratio, S0 (0.16 ≤ So ≤ 0.71) and the surfactant concentration, c (0.1032 ≤c (mol•dm-3 ) ≤ 0.7806). The frequencies ranged from 100 MHz to 89 GHz. An analysis of a particular solution is conducted over the temperature range of 278.15 to 328.15K in order to calculate the energy of the activation parameters. At 298.15 K, the spectra are fitted to a total of five Debye processes for concentration dependency series and three Debye processes for temperature dependence series. Br- surface and bulk diffusion surrounding the micelles best describes the two low frequency dispersions, at 100 MHz and 0.8 GHz, respectively. These mechanisms were examined using Grosse theory. The Maxwell-Wagner relaxation process is equivalent to high frequency micelle dispersion at 0.8 GHz. The thickness of the conducting shell of the micelle is determined by using the electrical conductivity of the particles and parameters taken from the Grosse theory, and the results are comparable to those from an examination of the Pauly and Schwan model. The Grosse model and solvent dispersion analysis were used to calculate the volume fractions of micelles. Both approaches were in agreement. The surfactant head group non-rotationally hydrates almost ~7±1 water molecules. Styrene addition allows for the non-rotationally bound accommodation of an additional ~7±1 water molecules.