13C-NMR Study of aerosol OT in aqueous and organic solvents

Abstract

The dynamic behavior of Aerosol OT in the monomeric state in methanol and in micellar states in water, chloroform and benzene has been studied by measurement of 13C-NMR spin-lattice relaxation time ( T 1) with the following results. The correlation time for the overall reorientation of micelle or monomer calculated from T 1 was compared with that calculated from the viscosity of the solvent and a reasonably postulated radius of the solute particle, showing good agreement in organic solvents. In the micellar state the motion near the polar head group was restricted and the segmental mobility was increasing as one moves along the chain away from the polar group. This trend was significantly noticeable in organic solvents, where the polar head group serves to anchor the chain of Aerosol OT molecules. Also, the 13C-NMR chemical shifts and the effects of lanthanide shift reagents, Yb( fod) 3 in organic solvents and Pr(NO 3) 3 in water, were measured and analyzed on the basis of the molecular conformation and micellar structure of Aerosol OT.