WATER-INDUCED MICELLAR STRUCTURES OF BLOCK COPOLY(OXYETHYLENE-OXYPROPYLENE-OXYETHYLENE) IN O-XYLENE

We previously reported the water-induced micelle formation of copoly(oxyethylene-oxypropylene-oxyethylene), Pluronic L64, in o-xyIene. The micellar properties could be controlled by varying the water to EO ratio (Z) in micelles. In this paper, laser light scattering, transient electric birefringence (TEB), and synchrotron small-angle x-ray scattering (SAXS) were used to study the micellar structure at different Z values. Both TEB and SAXS results further confirmed the micellar shape transition from that of a sphere to a nonspherical shape. A comparison between TEB and dynamic light-scattering results as well as the SAXS experiments showed an ellipsoidal shape for micelles when Z > 1.3 with the oblate being the more reasonable form for fitting all the experimental parameters. The degree of asymmetry appeared to be not high. (C) 1993 John Wiley & Sons, Inc.