Influence of charge density of anionic polyelectrolytes on structure formation in liquid crystalline systems

The influence of different amounts of anionic copolymers of N-Methyl N-viny l acetamide (NMVA) and acrylic acid with various charge densities on the fo rmation of the lamellar liquid crystal formed by sodium dodecyl sulfate (SD S)/decanol/water was investigated by means of polarization microscopy, smal l angle x-ray scattering (SAXS), transmission electron microscopy and rheol ogy. On the contrary to the incorporation of poly(acrylic acid) a one phase lamellar liquid cristalline region was obtained in all investigated formul ations with the different copolymers. Although a shrinking of the Liquid cr istalline region for all systems that contain copolymers could be generally proved by SAXS-measurements, no change of the phase boundaries due to the different amounts or charge densities could be shown over a wide range. How ever, for the investigated weight ratios water / (SDS + decanol) the interl ayer spacings of the lamellar mesophases decreased with increasing copolyme r amount whereas the value for the extrapolated interlayer spacing ( d(0)) remained constant. Transmission electron microscopy proves the formation of spherical supramol ecular structures in good agreement with the rheological behaviour of the s ystems.