A SCATTERING STUDY ON INTERMICELLAR INTERACTIONS AND STRUCTURES OF POLYMERIC MICELLES

The micellar structure is usually considered to be composed of a hard sphere (liquid) core and a heavily solvated corona. Therefore, the cor rection for intermicellar interactions at finite concentrations can be relatively complicated. In this article, small-angle neutron scatteri ng of a copolymer, known as Pluronic L64 (PEO(13)PPO(30)PEO(13)), in o -xylene in the presence of D2O is used to demonstrate that, based on t he hard sphere approximation, intermicellar interactions can be correc ted by representing the micellar size as having an equivalent hard sph ere radius. The procedure remains valid even if the micellar shape bec omes asymmetric, with axial ratios of 3 similar to 4. For the present system, the equivalent hard sphere radius corresponds to the micellar core radius plus one-half of the micellar shell thickness. With the eq uivalent hard sphere approach, the scattering behavior of the micelle could be described by using a core-shell structure. (C) 1994 John Wile y and Sons, Inc.