Abstract
Stack, chimneylike, and threadlike assemblies have previously been proposed for the structure of disodium cromoglycate (DSCG) aggregates in aqueous solutions. The results of the synchrotron x-ray scattering investigations reported here reveal the formation of simple columnar assemblies with π-π stacking at a separation of 3.4 Å between the DSCG molecules. Lateral separation between the assemblies is concentration and temperature dependent, varying from ∼35 to 42 Å in the orientationally ordered nematic () phase and from 27 to 32 Å in the columnar or middle () phase having long range lateral positional order. The assemblies’ length depends on concentration and consists of ∼23 molecules in the phase, becoming three to ten times larger in the phase. The scission energy is concentration dependent in the phase with values ∼7.19 ± 0.14 (15 wt %), 2.73 ± 0.4 (20 wt %), and 3.05 ± 0.2 (25 wt %). Solutions of all concentrations undergo a spinodal decomposition at temperatures above ∼40 °C, resulting in DSCG-rich regions with the phase and water-rich regions in the and isotropic phases.
2 More- Received 13 February 2014
DOI:https://doi.org/10.1103/PhysRevE.89.062504
©2014 American Physical Society