PUB - Publikationen an der Universität Bielefeld

It is shown how a system containing two or more distinctly different types of self-assembled aggregates can be characterized by a combination of scattering methods. The system studied represents an aqueous micellar solution of a poly(paraphenylene) type oligomer in which each benzene unit of the aromatic backbone is doubly substituted with a hydrophobic and a hydrophilic group, viz., an alkyl chain (-C12H25) and an oxyethylene chain (-CH2O(EO)(3)Me). This oligomer, in which the boundary hydrophobic/hydrophilic is parallel to the aromatic backbone, is insoluble in pure water but soluble in micellar solutions of nonionic surfactants like C8E4. Cryogenic transmission electron microscopy reveals the existence of fiberlike aggregates of mean length greater 200 nm and a diameter of ca. 6 nm in an excess of small surfactant micelles. Static and dynamic light scattering and small-angle neutron scattering (SANS) were used to characterize this complex liquid, and the scattering data were analyzed by model-based and model-independent procedures. (C) 2003 American Chemical Society.