Studies on the Hydrodynamic Diameter and Aggregation Number of Nonionic Switchable Surfactant

Abstract

An Investigation of the micelle aggregation number (N) and hydrodynamic diameter (Dh) is conducted on nonionic switchable surfactant 11-ferrocenylundecyl polyoxyethylene ether (FPEG), the micelle aggregation number of FPEG solution is determined by steady-state fluorescence probe, the results show that the micelle aggregation number (N) increase linearly with the concentration range from 5 to 12 times CMC of FPEG solutions. The critical micelle aggregation number Nmwhich means that the aggregation number of surfactant at the concentration of CMC is calculated to be 66. The hydrodynamic diameter (Dh) of FPEG micelle is determined by dynamic light scattering (DLS), the measurement angle is fixed at 90°and the wavelength is 532nm, the distribution data analyses by NNLS (non-negatively constrained least square) algorithm, the results reveal that the mean value of Dhat the concentration of 0.5 mmolL-1is 7.8nm. the POLY value, which used to explain the micelle polydispersity in the aqueous solution, is measured and the results show that the POLY values are slightly different, this indicates that the micelle aggregation morphology of FPEG is polydispersity in the aqueous solution.