Small angle neutron scattering of D2O-Brij 35 and D2O-alcohol-Brij 35 solutions and their modelling using the Percus-Yevick integral equation

Abstract

Small angle neutron scattering of direct micelles in binary surfactant-D2O and ternary surfactant-alc.- D2O systems was measured. The nonionic surfactant was poly(oxyethylene-23) lauryl ether (C12E23, com. name: Brij 35) which was used at concns. far beyond its crit. micellar concn.: between 0.1 and 15% (∼1.0 × 10-3-1.5 × 10-1 mol L-1). The alcs. were butan-1-ol, pentan-1-ol, hexan-1-ol, heptan-1-ol at concns. of ∼0.25 mol L-1. The spectra could quant. be modeled by the Percus-Yevick integral equation method in combination with a core/shell model yielding detailed information about the size, the (ellipsoidal) shape, the aggregation no., the internal structure and the distribution of the micelles. The ternary systems were modeled with an addnl. parameter, the partition of the alc. between the outer aq. bulk and the inner micellar pseudo-phase. In the case of the pentanol system the partition coeff. inferred from NMR self-diffusion measurements was used to describe the scattering result.