Structure formation in polymer-modified liquid crystals

The objective is the investigation of the influence of tao different polyme rs in a lamellar liquid crystalline sodium dodecyl sulfate (SDS)/decanol/wa ter system. The polymers are, on the one hand, uncharged poly(ethylene glyc ol) (PEG), whose molecular weight is varied, and, on the other hand, a poly cation with differing charge densities made of diallyldimethylammonium chlo ride (DADMAC) and N-methyl-N-vinylacetamide (NMVA). Applied methods were ma inly small-angle X-ray diffraction (SAXS), rheology, and electron microscop y, Our major results are the observation of two coexisting lamellar structu res of which one is a "nonswelling'' and the other a "swelling" structure, which form multilamellar spherical structures on a supramolecular level. Ho wever, the variation of the molecular weight of PEG can be neglected, where as the alteration of the charge density has a pronounced influence on the s tructure. Generally, one can conclude that the phenomena observed here can be understood on the basis of polymer-polymer interactions in contrast to p olymer-surfactant interactions of preliminary electrostatic nature. (C) 199 9 Academic Press.