Amphiphilic block copolymers in aqueous-polar organic solvent mixtures: Phase behavior and structure

Amphiphilic block copolymers of the poly(ethylene oxide)-poly(propylene oxide) (PEO-PPO) family are well known for self-assembling in the presence of water (selective solvent for PEO) into cubic, hexagonal and lamellar lyotropic liquid crystals. We are interested on how the aqueous phase behavior and structure of these polymeric amphiphiles can be modulated by the addition of polar organic solvents (e.g., glycerol, ethanol). Mixtures of water with two organic solvents (glycerol and ethanol) constitute a specific focus of this work. Our studies combine macroscopic observations (e.g., phase diagrams) with microscopic measurements (from small-angle X-ray scattering), and aim to relate the type of structure formed and its characteristic dimensions to the relative swelling of the polymer blocks and to the location of the solvent in the amphiphile assembly. Solvent-induced structural changes of block copolymers have interesting repercussions on the formulations and nonmaterial's synthesis in such media.