Self-Assembly of Amphiphilic Block Copolymers in Ternary Solvent Mixtures: Lyotropic Liquid Crystalline Phase Behavior and Structure

The effects of the simultaneous addition of two organic solvents (glycerol and ethanol) on the lyotropic liquid crystalline (LLC) phase behavior and structure formed by PEOPPOPEO amphiphilic block copolymers in water are examined. Glycerol and ethanol have been selected because of their opposite effect: structure promoting and structure dissolving, respectively. Lattice parameters of Pluronic P105 (EO37PO58EO37) and F127 (EO100PO70EO100) LLC samples in the presence of any type and amount of E+G solvents decrease with increasing volume fraction of the PPO-rich domains. Lattice parameters for the two block copolymers fall on the same line when normalized with the square root of polymer molecular weight, suggesting weak block segregation.