Extremely slow counterion dynamics in xanthan liquid crystal through 23Na and 14N NMR

J. R C Van der Maarel, D. E. Woessner, M. E. Merritt

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

To describe the structure and dynamics in a lyotropic xanthan liquid crystal, we have done 23Na and 14N NMR experiments. The spectra are consistent with a powder average over randomly oriented liquid-crystalline domains. From 14N quadrupolar echo experiments it was concluded that the exchange among the several micron sized domains is slow with residence times in the millisecond range. Conventional spin-lock experiments (14N and 23Na) as well as spin-lock experiments filtered through the quadrupolar spin polarization order (23Na only) revealed the existence of an extremely low frequency, submegahertz dispersion in the spectral densities pertaining to both sodium and ammonium counterions. The corresponding correlation times are on the order of tens of microseconds and agree with a structural correlation length on the order of 500 nm. The latter correlation times reflect the rearrangement of counterions among polymer segments over the same spatial extent as the polymer persistence length.

Original languageEnglish (US)
Pages (from-to)3864-3871
Number of pages8
JournalJournal of Physical Chemistry B
Volume106
Issue number15
DOIs
StatePublished - Apr 18 2002

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Liquid Crystals
Liquid crystals
liquid crystals
Nuclear magnetic resonance
nuclear magnetic resonance
extremely low frequencies
Polymers
Experiments
polymers
Spin polarization
Spectral density
echoes
Ammonium Compounds
sodium
Powders
Sodium
polarization
liquids
Crystalline materials
xanthan gum

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Extremely slow counterion dynamics in xanthan liquid crystal through 23Na and 14N NMR. / Van der Maarel, J. R C; Woessner, D. E.; Merritt, M. E.

In: Journal of Physical Chemistry B, Vol. 106, No. 15, 18.04.2002, p. 3864-3871.

Research output: Contribution to journalArticle

Van der Maarel, J. R C ; Woessner, D. E. ; Merritt, M. E. / Extremely slow counterion dynamics in xanthan liquid crystal through 23Na and 14N NMR. In: Journal of Physical Chemistry B. 2002 ; Vol. 106, No. 15. pp. 3864-3871.
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