Browsing by Author "Ward, Meryck"

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    Actuation behaviour of a derivatized pyrrole accordion type polymer
    (ESG, 2014) Ward, Meryck; Botha, Shanielle; Iwuoha, Emmanuel I.; Baker, Priscilla
    A monomer (Phenazine-2,3-diimino(pyrrole-2-yl)–PDP) derived from the condensation reaction between 2,3-diaminophenazine and a pyrrole derivative has been synthesized as a hinge molecule in the design of a zig-zag polymer. The monomer was polymerized both chemically and electrochemically in order to produce the polymer material, phenazine-2,3-diimino(pyrrole-2-yl (PPDP). During electrochemical polymerization the system was doped using 1,4-napthaquinone sulphonic acid (NQSA) and polyvinylsulfonic acid (PVSA) respectively, to improve conductivity. Characterization of the materials by Fourier transform infrared spectroscopy (FTIR) confirmed the successful linking of the starting materials to produce the hinge molecule and nuclear magnetic resonance spectroscopy (NMR) supported the FTIR data. The electrochemistry of the polymer in the doped and undoped state was evaluated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).
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    Development of Schiff base electrochemical sensors for the evaluation of polycyclic aromatic hydrocarbons in aqueous medium
    (University of the Western Cape, 2017) Ward, Meryck; Baker, Priscilla G.L.; Aubert, Pierre-Henri
    A novel monomer (N,N'-Bis-(1H-pyrrol-2-ylmethylene)-benzene-1,2-diamine-BPPD) was derived from the condensation reaction between o-phenylenediamine and a pyrrole derivative. The monomer was polymerized electrochemically to produce the new polymer material - polymerized(N,N'-Bis-(1H-pyrrol-2-ylmethylene)-benzene-1,2-diamine) PBPPD. This novel polymer material was deposited at the surface of a screen-printed carbon electrode, as a thin film, in the development of chemical sensors for the detection of polycyclic aromatic hydrocarbons (PAHs). The monomer material was characterized in terms of its optical (spectroscopy) and thermal properties. The polymer material was characterized in terms of its surface morphology and its redox electrochemistry. Fourier transform infrared spectroscopy (FTIR) was used to confirm the azomethine bond formation during the condensation reaction of an aldehyde and primary amine derivative.
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    Electrochemical actuation potential of diaminophenazine linked pyrrole derivatives
    (2013) Ward, Meryck; Baker, Priscilla
    A novel monomer (Phenazine-2,3-diimino(pyrrole-2-yl)–PDP) derived from the condensation reaction between 2,3-diaminophenazine and a pyrrole derivative has been synthesized as a hinge molecule in the design of a zig-zag polymer with actuation possibility. The monomer was polymerized chemically and electrochemically to produce the new polymer material – polymerized Phenazine-2,3-diimino(pyrrole-2-yl) PPDP. Two very crucial properties of a good actuator material, relate specifically to its solubility testing and electrical conductivity. The hinged polymer material was studied intensively in terms of its spectroscopy; Fourier Transform Infrared - FTIR, 1H’NMR, thermal properties (Differential Scanning Calorimetry-DSC and Thermogravimetric Analysis-TGA) as well as voltammetry and conductivity. Conductivity was evaluated using three different approaches including; 4 probe measurements, plotting of I/V curves based on potentiostatic measurements and an electrochemical impedance experiment using a dielectric Solartron interface. Electrochemical kinetics of the polymer prepared as a thin film at glassy carbon electrode (GCE) was also done and it was clear that the thin film conductivity was vastly different from the compressed pellet conductivity (thick film). The zig-zag polymer was then further modified by homogeneous inclusion of gold nanoparticles to improve conductivity and solubility, in the thick film arrangement. Conductivity of the thin film was studied by electrochemical impedance spectroscopy with the relative charge transfer values being determined for unmodified and modified polymer systems. The solubility testing of the material plays an important role as it is required for a wide range of experimental applications. The zig-zag polymer showed great promise for applications; in dye sensitized solar cells and free standing interpenetrating polymer network (IPN), solubility testing and electrical conductivity would need to be improved in order to be used in these applications.