Structure and Dynamics of Thermotropic Liquid Crystalline and Solid Phases of Sodium Alkanoates (Nmr)

The neat (smectic A) phase of anhydrous sodium alkanoates is studied by means of NMR, polarization microscopy, and X-ray diffraction. The domain sizes, ('23)Na spin-lattice relaxation times T(,1), and the ('23)Na quadrupolar coupling constants (QCC) in neat phase sodium 3- and 4-methylpentanoates are compared with results in other short-chain sodium alkanoates. The magnitude of the ('23)Na QCC and its dependence on the ionic lateral packing area are explained quantitatively by a quasi-crystalline model in which the cations and the carboxylate groups are arranged in a double-layered square array. The drop in the ('23)Na T(,1) at the clearing point in all salts is discussed. In a preliminary ('23)Na NMR study of sodium stearate, the sodium ion apparently experiences an effectively isotropic environment in the neat phase, while ('23)Na spectra in the superwaxy and subneat phases indicate a distribution of sodium sites.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Phillips, Margaret Levin

• Chemistry, Physical

Identifier

(UMI)AAI8711852

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/70363