Viscosity B coefficients of some alkyltrimethylammonium bromides and the effect of added alkan-1-ols

Abstract

The viscosity B coefficients for aqueous solutions of alkyltrimethylammonium bromides and decyltrimethylammonium bromide containing various concentrations of aliphatic alcohols have been determined at 25 °C. Viscosity B coefficients for the alkyltrimethylammonium bromides were positive and increased as the alkyl chain length increased; the B coefficient increase per methylene group was 0.084. The addition of aliphatic alcohols decreased the viscosity B coefficient of decyltrimethylammonium bromide. As the alcohol concentration was increased the measured partial molal volume V_s of decyltrimethylammonium bromide first decreased and then increased, and this was correlated with the viscosity B coefficient. The addition of alcohol is thought to effect the solvent structure and solute–solvent interactions by changing the composition and dielectric constant of the environment.