University of Illinois Urbana-Champaign

Nmr and Polarization Microscopy Studies of Sodium Alkyl Carboxylate Solids and Melts

Bonekamp, Jeffrey Edward

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Description

Title
Nmr and Polarization Microscopy Studies of Sodium Alkyl Carboxylate Solids and Melts
Author(s)
Bonekamp, Jeffrey Edward
Issue Date
1982
Department of Study
Chemistry
Discipline
Chemistry
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Chemistry, Physical
Abstract
  • The dynamic structure of the ionic liquid crystalline mesophase of both sodium n-butyrate and sodium isovalerate is studied using pulsed and Fourier transform NMR. Both the ('1)H self-diffusion measurements and the ('23)Na spin-lattice relaxation time, T(,1), and quadrupole coupling constant,
  • (DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI)
  • The design of a low-noise, four-pulse, heterodyne, NMR spectrometer is discussed in the appendix.
  • data indicate independent, rapid anion and cation diffusion in two dimensions. A measure of the anion order parameter, S, is obtained from the (omega)(,1) dependence of the ('1)H spin-lattice relaxation time in the rotating frame, T(,1(rho)). An expression is proposed which allows the calculation of the dielectric constant, (epsilon)(,(PARLL)), parallel to the mesophase order director using
  • data. An empirical correlation between (epsilon)(,(PARLL)) and S is discussed.
  • ('23)Na T(,1) and
  • data is obtained and compared for both the isotropic melt and the mesophase of sodium n-butyrate, sodium isovalerate, sodium n-valerate, sodium hexanoate, and sodium heptanoate. For these carboxylates studied, a relationship between the expected molar volume and the correlation time, (tau)(,c), for the electric field gradient fluctuation is discussed. The data also suggests that the Na('+) ion diffuses more rapidly two-dimensionally than it does three-dimensionally for these five melts.
  • The smectic A liquid crystalline structure is confirmed for the five sodium alkyl carboxylate mesophases using polarization microscopy. Both the birefringence temperature coefficient and the domain size (500(mu)m) are unusually large for sodium isovalerate. An empirical correlation between birefringence and the order parameter, S, is also found for sodium isovalerate.
  • ('23)Na NMR measurements for the solid phases of sodium isovalerate and sodium n-butyrate suggest that a dynamic disorder of the cation sublattice exists above 425(DEGREES)K for solid sodium isovalerate and throughout solid I and II sodium n-butyrate. It is possible that solids I and II sodium n-butyrate may be fast ion conducting phases. ('1)H T(,1) and T(,1(rho)) measurements indicate that solid I is an orientationally disordered crystalline (ODIC) phase (anion lattice).
Graduation Semester
1982
Type of Resource
text
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http://hdl.handle.net/2142/70180

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