Characterization of Mixed Micelles of SDS and a Sugar-Based Nonionic Surfactant as a Variable Reaction Medium

摘要: Time-resolved fluorescence quenching (TRFQ), electron paramagnetic resonance (EPR), and small-angle neutron scattering (SANS) are employed to characterize mixed micelles of sodium dodecyl sulfate (SDS) the nonionic sugar-based surfactant dodecylmalono-bis-N-methylglucamide (DBNMG) as a reaction medium. Interpretation results from three methods constrained fit classical model hydrocarbon core surrounded by polar shell. As measured TRFQ, at 45 °C, aggregation numbers increase 48 for pure SDS maximum 63 36 mole percent DBNMG decrease again 49 DBNMG. The 33 21° Ct o 45°C. SANS interpreted fixing number (from TRFQ) allowing shell thickness vary fitting parameter, yielding value 5.8 A °C. EPR, utilizing hydrophobic spin probe, is used measure nonempirical polarity index, H(25 °C), °C) defined be ratio molar concentration OH dipoles in solvent or mixture that water 25 °C; thus, both sugar headgroups contribute. By volume inaccessible due presence (127 3 ) (580 ), theoretical values computed, result depending only on bonds available interact with probe. constant average 7.4 out possible 10 reproduces over full range micelle compositions. At microviscosity shell, deduced rotational correlation time varies 2.79 ( 0.05 cP 13.1 0.2 departing slightly linear dependence fraction uncertainties viscosity standard deviations measurements therefore represent uncertainty relative viscosity. decreases 32 4c P 21°C °C micelles. These viscosities show rate pyrene dimethyl benzophenone, follows Stokes-Einstein-Smolukhovsky equation probability 0.5 whether composition changed temperature if varied enters into formulation because effective quencher depends volume; however, rates not correlated alone.