Theoretical UV-VIS spectroscopy and molecular simulations on doped polyaniline as a hydrazine sensor / Fatin Nadzirah Sabri

Fatin Nadzirah , Sabri (2018) Theoretical UV-VIS spectroscopy and molecular simulations on doped polyaniline as a hydrazine sensor / Fatin Nadzirah Sabri. Masters thesis, University of Malaya.

	PDF (The Candidate's Agreement) Restricted to Repository staff only Download (1518Kb)
Preview	PDF (Thesis M.A) Download (3559Kb) | Preview

Abstract

Polyaniline (PANI) is one of the conducting polymers known to have a reasonably good conductivity, is easy to prepared, stable, affordable and manifests redox properties. It has received attention in comparison to other organic compounds through on-going research work performed either in its native state or functionalized form. Emeraldine base, (EB) is acknowledged as the most useful form of PANI due to its high stability at room temperature. Besides, EB can be doped to the emaraldine salt (ES) which is the conducting form of the polymer. As for this study, EB has been doped with anions called sodium dioctyl sulfosuccinate (AOT⁻) to use as a hydrazine sensor and the detection of hydrazine is then observed by using ultraviolet-visible (UV-VIS) spectroscopy. In order to have an insight into the conductivity mechanism as well as its effect on the UV-VIS spectroscopy, a comprehensive study about the molecular and electronic properties of different degrees of polymerization have been explored using quantum mechanical calculations together with molecular dynamics simulation. Through our computational study, it had been found that dimer form of ES that is composed of 8 rings in ratio of 1:1 benzoid and quinoid shows the closest ES UV-VIS peak with experimentally observed result. On the other hand, semi-empirical AM1 and PM6 as well as DFT (B3LYP functional) show the most reliable UV-VIS absorption peak simulation using the dimer model in comparison with the experimental spectra. Then again, DFT with B3LYP calculations are the most reliable calculations, manifesting a consistent lambda peak reduction as more cations at the ES chain are reduced. This is observed during the dedoping process simulation conducted on tetramer and ES compared to the experimental results.

Actions (For repository staff only : Login required)