Cationic organoiron polyelectrolyte three-arm stars.
|Title||Cationic organoiron polyelectrolyte three-arm stars.|
|Author(s)||A. Abd-El-Aziz, S. Carruthers, E. Todd, T. Afifi, J. Gavina|
|Journal||Section Title: Chemistry of Synthetic High Polymers, Journal of Polymer Science, Part A: Polymer Chemistry|
|Abstract||With nucleophilic arom. substitution and ester condensation reactions, several new first-generation dendrimers and star-shaped mols. contg. cationic cyclopentadienyl iron moieties were prepd. Although the soly. of the organoiron star-shaped mols. with ether bridges in polar solvents was found to decrease with an increase in the size of the mol., the addn. of ester linkages resulted in a sharp decrease in the soly., regardless of the size. The thermal behavior of these mols. was examd. with differential scanning calorimetry and thermogravimetric anal. The glass-transition temps. (Tg's) of these star-shaped mols. ranged from 123 to 170 Â°C. However, the addn. of the ester functionality allowed for an increase in the Tg's to 151-194 Â°C. The star-shaped mols. were thermally stable up to 200 Â°C, above which a loss of the cationic cyclopentadienyl iron moieties occurred. Degrdn. of the ester chains started at 321 Â°C, and degrdn. of the ether chains started at 408 Â°C. Electrochem. studies of the ether star-shaped mols. showed a redn. of the 18-electron iron centers to 19-electron centers. This redox system was reversible at low temps., whereas it was irreversible at room temp. Moreover, an increase in the no. of metal moieties caused an overlap and broadening of the redox wave. Viscosity studies showed a polyelectrolyte effect for the organoiron star-shaped mols. [on SciFinder(R)]|
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