A scattering study on intermicellar interactions and structures of polymeric micelles

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Abstract
The micellar structure is usually considered to be composed of a hard sphere (liquid) core and a heavily solvated corona. Therefore, the correction for intermicellar interactions at finite concentrations can be relatively complicated. In this article, small‐angle neutron scattering of a copolymer, known as Pluronic L64 (PEO13PPO30PEO13), in o‐xylene in the presence of D2O is used to demonstrate that, based on the hard sphere approximation, intermicellar interactions can be corrected by representing the micellar size as having an equivalent hard sphere radius. The procedure remains valid even if the micellar shape becomes asymmetric, with axial ratios of 3 ˜ 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 equivalent hard sphere approach, the scattering behavior of the micelle could be described by using a core‐shell structure. © 1994 John Wiley & Sons, Inc.