| Abstract: | Small‐angle X‐ray scattering (SAXS) has been used to study the nanostructures of complexes formed by slightly crosslinked anionic copolymer gels of poly(sodium methacrylate‐co‐N‐isopropylacrylamide) [P(MAA/NIPAM)] interacting with cetylpyridinium bromide (CPB), and alkyltrimethylammonium bromide (CnTAB, 10 ≤n ≤ 18), respectively. Both the charge density of polyelectrolyte gels and the surfactant alkyl tail length could induce the phase structure transition from Pm3n space group cubic to hexagonal close packing of spheres (HCP), while the different polar groups of pyridinium and trimethylammonium with the same hydrophobic cetyl chain in surfactants had no significant effects on the structures of complexes formed with the same gels. The highly ordered structures were shown to be formed by the self‐assembly of ionic surfactants inside the anionic gel network, driven by both electrostatic and hydrophobic interactions. Freeze drying the water‐equilibrated complexes could collapse the formed ordered structures. However, the highly ordered structures could be restored after the dried complexes were reswollen by water under the same conditions, indicating that the highly ordered water‐equilibrated complexes were thermodynamically stable. Copyright © 2000 John Wiley & Sons, Ltd. |
