Award Date

12-1-2012

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Committee Member

Pradip K. Bhowmik

Second Committee Member

Vernon F. Hodge

Third Committee Member

Kathleen A. Robins

Fourth Committee Member

Laxmi P. Gewali

Number of Pages

189

Abstract

Pyridinium salts, both molecular and polymeric, are an interesting class of multifunctional materials that exhibit liquid-crystalline and light-emitting properties. Moreover, their properties can be easily tuned by introducing new types of anions or by modifying their chemical structures. This dissertation describes synthesis and characterization of poly(pyridinium salt)s containing macrocounterions and fluorene moieties in their backbones, synthesis and characterization of nanocomposites of poly(pyridinium salt)s with single-walled carbon nanotubes via non-covalent interactions, and synthesis and characterizations of pyridinium salts having different aliphatic linkages and their application in organic acid sensing.

First, all of these ionic polymers were prepared by either ring-transmutation or by metathesis reaction. Their chemical structures were established by FTIR, 1H spectroscopy and elemental analysis. Some polymers containing macrocounterions had relatively low melting transitions above which they formed thermotropic liquid-crystalline phase; and other polymers were amorphous as determined by VTXRD studies. Ionic polymers containing fluorene moieties in their backbones exhibited lyotropic properties in both polar protic and aprotic solvents at various critical concentrations. Light emission properties of this class of polymers in common organic solvents as well as in water and in solid states were also studied. To explore the application of poly(pyridinium salt)s, we developed a method of preparation of nano-composites with a number of poly(pyridinium salt)s and single-walled carbon nanotubes. The single-walled carbon nanotubes were effectively dispersed with various poly(pyridinium salt)s resulting in nanocomposites. The optical and solution properties of these composites were examined by a number of experimental techniques. Finally, some of the synthesized dicationic salts exhibited ionic liquid properties, but all exhibited fluorescent properties in solution and solid states. Due to the presence of methyl orange counterions, pyridinium salts could serves as a pH sensor in organic solvents.

Keywords

Carbon nanotubes; Pyridinium compounds – Properties; Salts

Disciplines

Chemistry | Nanoscience and Nanotechnology | Polymer Chemistry

Language

English


Share

COinS