Liquid crystalline polyanion/polycation/water systems

Abstract The phase diagrams of polyanion/polycation/water systems with varying acidity of the ionic groups of the polyanion were investigated. The phase diagram of the ternary system poly(styrenesulfonic acid) (NaPSS), poly(diallyldimethylammonium chloride) (PDADMAC) and water is dominated by a macroscopic phase separation due to the formation of polyelectrolyte complexes. A transition to macroscopic homogeneous systems is only observed for concentrated samples, if one component is in excess. By replacing NaPSS by a statistical copolymer with maleic acid, the region of macroscopic phase separation becomes smaller and macroscopically homogeneous one phase systems are now formed over a much wider range of the phase diagram. Concentrated, macroscopically homogeneous polyanion/polycation/water systems were investigated by comparing them to the corresponding concentrated aqueous polyelectrolyte solutions by means of polarized-light microscopy, differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS) and electron microscopy (EM). Concentrated aqueous polyanion solutions show a temperature induced spherulitic crystallization. The addition of a cationic polyelectrolyte decreases the crystalline order and induces the formation of a temperature controlled liquid crystalline phase.