Computation of molecular properties and physical characterization of doped and undoped polyaniline

Date

4-2005

Degree

Bachelor of Science in Applied Physics

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Maricon R. Amada

Co-adviser

Ernesto J. Del Rosario

Abstract

Computational and experimental studies were done on polyaniline in order to determine the molecular properties of the emeraldine base and salts. HyperChem 7,0 was used to compute the molecular properties of the undoped and doped polyaniline. Different molecular properties were obtained from the optimized structures of undoped structures (leucoemeraldine base, emeraldine base and pernigraniline base) and doped strictures (PANi-HI, PANi-CH2COOH, and PANi-HCIO.,) These different molecular properties include HOMO and LUMO energies, energy gap, bandwidth, dipole moment, ionization potential, electron affinity, total energy, heat of formation and mean polarizability. Results showed that after doping, the PANi polymers have a greater stability, ionization potential, electron affinity and bandwidth. For the emeraldine salts, PANi-HC10,1 was observed to exhibit the highest electrical conductivity and associated molecular properties, followed by PANi-CH2COOH and PANi-HI The incorporation of dopant anions like perchloric acid and acetic acid enhanced the conductivity of the polymer. However, the conductivity of the PANi-HI could not be determined because of its very large resistance. This was attributed to the side reactions during the polymerization reaction. Polymerization of polyaniline followed nucleation growth based SEM images of the polymers. Globular structures (sponge-like and coral-like) and void spaces were observed in the morphology of the polymer except for PANi-HI which has sharp edges and loose flaky structures. Pelletized polymers have reduced void spaces but the formations of boundaries were evident. Benzenoid and quinoid rings were determined from the structures of the fabricated conducting polymers. Other functional groups that describe the nature of oxidation of polyaniline were also obtained. The effects of dopant ions on the polymer were not observed in the SEM image but some were revealed in the FTIR spectroscopy. Endothermic temperature was observed from the DTA graph of the doped and undoped polyaniline. Doping of the polymer reduced the transition temperature of the polymer.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

Thesis

Document Type

Thesis

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