Abstract
AbstractPolypyrrole/chitosan (PPy/Cs) nanocomposites with various amounts of polypyrrole nanoparticles (PPy‐NPs) have been synthesized and afterwards exposed to UV irradiation for 240 min. Structure, dynamics and antibacterial activity of pure compounds and the corresponding nanocomposites were investigated by means of wide‐angle X‐ray scattering, Fourier transform infrared spectroscopy, transmission electron microscopy, thermogravimetric analysis, broadband dielectric spectroscopy and antibacterial activity assay. The occurrence of a pronounced interaction between PPy‐NPs and Cs has been verified. Broadband dielectric spectroscopy measurements revealed two relaxation processes at low and high frequencies. The low‐frequency α‐relaxation associated with the glass–rubber transition is attributed to the presence of hydrogen‐bonded water (plasticizing effect) appearing at low temperature (<373 K). The high‐frequency σ‐relaxation is related to water molecules which become desorbed upon heating at T > 373 K and demonstrates Arrhenius temperature dependence with activation energy in the range 70–90 kJ mol−1 in good agreement with previous reports. On the contrary, PPy‐NPs do not show any structural relaxation process and the charge transport mechanism follows the correlated barrier hopping model. All PPy/Cs nanocomposites exhibit an improved antibacterial activity against both Staphylococcus aureus and Escherichia coli bacteria as compared with pure Cs and PPy‐NPs. © 2018 Society of Chemical Industry
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