Disordered network state in hydrated block-copolymer surfactants.

Hydration of poly(butadiene-b-ethylene oxide) diblock copolymers leads to various ordered and disordered phases, analogous to the aqueous phase behavior of surfactants and lipids. Small-angle x-ray scattering measurements corroborated by cryogenic scanning electron microscopy imaging reveal a random network (N) morphology at polymer compositions and water content intermediate to those associated with ordered cylinders (H1) and lamellae (L). This sequence of self-assembled structures is strikingly similar to the phase behavior of certain water-oil-surfactant microemulsions.