Date of Award
University or Center
Clark Atlanta University(CAU)
Dr. Issifu I. Harruna
High performance polyamides containing the 4,4’-disubstituted-2,2’-bipyridyl moiety were synthesized by phosphorylation polycondensation from 2,2’-bipyridyl-4,4’-dicarboxylic acid and a series of primary aromatic diamines with triphenylphosphite and pyridine as the agents to facilitate condensation. Polyamides exhibiting improved solubility in organic solvents and strong acids, melting transitions at low temperatures and good thermal properties were prepared by introducing bulky methyl and fluoro groups, flexible ether and propyl linkages, and by using monomers with reduced symmetry. Solutions of the polyamides with rigid mainchains (II, III, IV, V, VI, and VIII) showed birefringence (colorful spherulites) at concentrations of 5, 10, and 15% w/v polymer/solvent. The immobilization of the bipyridyl units in the polymer matrix increases the metal ion sensing of the polymer by promoting a chelating interaction between the polyamides and metal ions.
The chelation of nickel (II) ions caused extensive crosslinking within the polymeric systems immediately precipitating insoluble metallopolymers. Ultra violet-visible data of the chromium (III) and zinc (II) extract yielded inconclusive evidence of metal ion chelation. The optical spectroscopic studies of the extraction of ruthenium ions by the 2,2’-bipyridyl containing polyamides revealed the formation of distinct ruthenium (II) complexes [RuII(poly)L4] (λmax=530nm), [RuII(poly)2L2] (λmax=584nm), and [Ru(poly)3]2+ (λmax=476nm), while iron (II) ions formed only one complex (λmax=569nm). The diverse functional features of the polymer repeat unit directly influences the chelation of metal ions. Subsequently, the chelation of ruthenium (II) ions resulted in the preparation of directional metallopolyamides systems based on the geometrically favorable tris(2,2’-bipyridyl)ruthenium (II) complex. The three-dimensional polyamides, which absorbed at λmax of 476nm and emitted at λmax of 620 nm, exhibited high thermal stability and improved solubility making them suitable candidates for compressive strength studies and cyclic voltammetry studies as part of an effort to address the corrosion of graphite-fiber reinforced composites.
Petzold, Odessa N., "Synthesis and characterization of metal ion sensing high performance polymers and directional metallopolymers" (1999). ETD Collection for AUC Robert W. Woodruff Library. 2989.