Synthesis and characterization of polypyrrole-palladium coated poly (styrene-butyl acrylate) nanocomposite emulsion
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Date
2016
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Universiti Teknologi Malaysia
Abstract
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
Description
Thesis (PhD. (Polymer Engineering))
Keywords
Polymerization, Emulsion polymerization, Nanocomposites (Materials)