Solvation Dynamics in Different Phases of the Lyotropic Liquid Crystalline System

Bibhisan Roy, Sagar Satpathi, Krishna Gavvala, Raj Kumar Koninti, Partha Hazra

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

Reverse hexagonal (HII) liquid crystalline material based on glycerol monooleate (GMO) is considered as a potential carrier for drugs and other important biomolecules due to its thermotropic phase change and excellent morphology. In this work, the dynamics of encapsulated water, which plays important role in stabilization and formation of reverse hexagonal mesophase, has been investigated by time dependent Stokes shift method using Coumarin-343 as a solvation probe. The formation of the reverse hexagonal mesophase (HII) and transformation to the L2 phase have been monitored using small-angle X-ray scattering and polarized light microscopy experiments. REES studies suggest the existence of different polar regions in both HII and L2 systems. The solvation dynamics study inside the reverse hexagonal (HII) phase reveals the existence of two different types of water molecules exhibiting dynamics on a 120-900 ps time scale. The estimated diffusion coefficients of both types of water molecules obtained from the observed dynamics are in good agreement with the measured diffusion coefficient collected from the NMR study. The calculated activation energy is found to be 2.05 kcal/mol, which is associated with coupled rotational-translational water relaxation dynamics upon the transition from "bound" to "quasi-free" state. The observed ∼2 ns faster dynamics of the L2 phase compared to the HII phase may be associated with both the phase transformation as well as thermotropic effect on the relaxation process. Microviscosities calculated from time-resolved anisotropy studies infer that the interface is almost ∼22 times higher viscous than the central part of the cylinder. Overall, our results reveal the unique dynamical features of water inside the cylinder of reverse hexagonal and inverse micellar phases.

Original languageEnglish
Pages (from-to)11721-11731
Number of pages11
JournalJournal of Physical Chemistry B
Volume119
Issue number35
DOIs
Publication statusPublished - Aug 13 2015
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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