| Abstract: | Ordered structures of micellar aqueous solutions of poly(ethylene glycol) (PEG) monododecylether mixtures [octaethylene glycol monododecylether (C12E8) and poly(ethylene glycol) monododecylether (C12E25)] have been investigated as a function of the C12E8/C12E25 composition by means of X‐ray scattering. C12E8 and C12E25 have different chain lengths of corona PEG, that is, 8 and 25 repeating units, respectively. The following results have been obtained. First, in the C12E8‐rich and C12E25‐rich regions, the mixtures take hexagonal and cubic phases, respectively. The hexagonal phase remains over a wider range of compositions and is more stable for the mixing of the other component than the cubic phase. Second, in the C12E8‐rich region of the cylindrical hexagonal packing, the nearest‐neighbor micellar distance increases, whereas the association number density remains constant, with an increasing amount of mixed C12E25 possessing longer corona chains. Third, in contrast to this, the nearest‐neighbor micellar distance of the body‐centered cubic packing exhibits almost no change, whereas the association number increases as C12E8 of shorter corona chains is increasingly incorporated. Fourth, self‐consistent field calculations reasonably reproduce the experimental findings of the second and third observations. We discuss the phase stability and the structural changes with the composition in terms of differences in the PEG corona‐chain length. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2474–2483, 2005 |
