Browsing by Author "Bahraeian, Sobhan"

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    Synthesis and characterization of polypyrrole-palladium coated poly (styrene-butyl acrylate) nanocomposite emulsion
    (Universiti Teknologi Malaysia, 2016) Bahraeian, Sobhan
    A conductive polypyrrole-palladium (Ppy-Pd) nanocomposite polymer shell was used to encapsulate poly (styrene-butyl acrylate )(poly(St-BA)) latex core. Poly(St-BA) core was prepared by emulsion polymerization at various glass transition temperature (Tg). The styrene:butyl acrylate (St-BA) monomer ratio was set at 77:23. From the measurement of differential scanning calorimetry and the analysis of minimum film formation temperature, Tg of poly(St-BA) was 51 °C and the copolymer formed uniform and smooth film. Peaks at 2872 cm-1, 1730 cm-1 and 1160 cm-1 from Fourier transform infrared spectra corresponding to symmetric and asymmetric stretching vibration of methyl group (-CH2-) of styrene as well as stretching vibrations carboxyl group (C=O) and aliphatic esters of BA confirmed the successful synthesis of poly(St-BA). The particle size of synthesized poly(St-BA) core was 25 nm, as measured by particle size analyzer. Later, the prepared poly(St-BA) core was encapsulated in situ with Ppy-Pd shell at various Ppy-Pd compositions. The thermal stability of poly(St-BA)/Ppy-Pd nanocomposite was increased with increasing Ppy loadings due to the deposition of Ppy char at the outer layer of the core. The char layer became a barrier that slowed down the degradation of poly(St-BA) core. The conductivity of nanocomposite was increased when compared to that of pure poly(St-BA) due to the adsorption of Ppy-Pd on the outer layer of the core particles that formed a continuous thin conductive pathway. The formation of this thin layer had nearly doubled the particle size from 25 nm of pure poly(St-BA) core to 46.57 nm of nanocomposite. The finding was supported by the micrograph obtained from transmission electron microscopy which showed the poly(St-BA) core was surrounded by the dark region, corresponding to Ppy-Pd layer. Effects of varying Ppy-Pd loading on the thermal stability and the particle size of nanocomposite were verified with the findings obtained from the optimization of reaction parameter using response surface method