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Isotropic-nematic phase equilibrium and phase separation of kappa-carrageenan in aqueous salt solution: Experimental and theoretical approaches

Chronakis, Ioannis S LU and Ramzi, M (2002) In Biomacromolecules 3(4). p.793-804
Abstract
The behavior of chiral-nematic and isotropic phases of helical kappa-carrageenan in aqueous solution of sodium iodide was compared with that of the anisotropic biphasic phase that contains both these phases. On the basis of birefringence, rheology, chemical analysis, average molecular weight, and polydispersity index measurements, we derived a number of characteristic differences as well as similarities between these phases, over a range of polysaccharide concentrations obtained by the dilution of each phase. For example, we assessed the critical concentration of an isotropic-anisotropic transition (C-i), the temperature of the anisotropic-isotropic phase shift during thermal heating-cooling cycles, and the viscosity changes due to the... (More)
The behavior of chiral-nematic and isotropic phases of helical kappa-carrageenan in aqueous solution of sodium iodide was compared with that of the anisotropic biphasic phase that contains both these phases. On the basis of birefringence, rheology, chemical analysis, average molecular weight, and polydispersity index measurements, we derived a number of characteristic differences as well as similarities between these phases, over a range of polysaccharide concentrations obtained by the dilution of each phase. For example, we assessed the critical concentration of an isotropic-anisotropic transition (C-i), the temperature of the anisotropic-isotropic phase shift during thermal heating-cooling cycles, and the viscosity changes due to the phase shift and due to the diminishing of the helical conformation. We also demonstrated how the different phases and their dilutions behave under the effect of shear and frequency of oscillation and how the viscoelastic properties vary in each phase and discussed the isotropic and anisotropic liquid crystal controlling behavior mechanisms. From a theoretical point of view, we propose to combine the wormlike chain model for semiflexible polyelectrolytes interacting via both hard-core and electrostatic repulsion to assess the concentration of isotropic-nematic transition, to assess the coexistence concentration range, and to determine the effects of charge by applying the effective diameter and a twisting effect. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Biomacromolecules
volume
3
issue
4
pages
793 - 804
publisher
The American Chemical Society
external identifiers
  • wos:000176716700022
  • scopus:0036057109
ISSN
1526-4602
DOI
10.1021/bm020015k
language
English
LU publication?
yes
id
993a3275-01aa-48f5-af45-30d6d91d4ca8 (old id 333882)
date added to LUP
2007-08-14 16:06:59
date last changed
2017-01-01 04:22:02
@article{993a3275-01aa-48f5-af45-30d6d91d4ca8,
  abstract     = {The behavior of chiral-nematic and isotropic phases of helical kappa-carrageenan in aqueous solution of sodium iodide was compared with that of the anisotropic biphasic phase that contains both these phases. On the basis of birefringence, rheology, chemical analysis, average molecular weight, and polydispersity index measurements, we derived a number of characteristic differences as well as similarities between these phases, over a range of polysaccharide concentrations obtained by the dilution of each phase. For example, we assessed the critical concentration of an isotropic-anisotropic transition (C-i), the temperature of the anisotropic-isotropic phase shift during thermal heating-cooling cycles, and the viscosity changes due to the phase shift and due to the diminishing of the helical conformation. We also demonstrated how the different phases and their dilutions behave under the effect of shear and frequency of oscillation and how the viscoelastic properties vary in each phase and discussed the isotropic and anisotropic liquid crystal controlling behavior mechanisms. From a theoretical point of view, we propose to combine the wormlike chain model for semiflexible polyelectrolytes interacting via both hard-core and electrostatic repulsion to assess the concentration of isotropic-nematic transition, to assess the coexistence concentration range, and to determine the effects of charge by applying the effective diameter and a twisting effect.},
  author       = {Chronakis, Ioannis S and Ramzi, M},
  issn         = {1526-4602},
  language     = {eng},
  number       = {4},
  pages        = {793--804},
  publisher    = {The American Chemical Society},
  series       = {Biomacromolecules},
  title        = {Isotropic-nematic phase equilibrium and phase separation of kappa-carrageenan in aqueous salt solution: Experimental and theoretical approaches},
  url          = {http://dx.doi.org/10.1021/bm020015k},
  volume       = {3},
  year         = {2002},
}