Hydrothermal synthesis and analysis of porous ZnO-Chitosan composites Kanako Kimura University of Leeds, UK This project explores the hydrothermal synthesis and analysis of porous ZnO-Chitosan (ZnO-CS) composites, study of the mechanism chitosan framework formation and the evaluation of the antioxidant properties of the composites. ZnO-CS composites, in three different ratios (ZnO:CS=5:1, 1:1 and 1:5), were synthesized at two different temperatures (180 and 220 °C) by a hydrothermal synthesis technique and characterized by FTIR, UV-Vis, SEM, FIB, PXRD, TGA and Zeta potential techniques. FTIR and SEM analysis proved a co-existence of ZnO with chitosan in the composites. ZnO-CS and ZnO-ExCS synthesized at 180 °C and ZnO-CS synthesized at 220 °C showed pores inside of the samples. The pore sizes vary, depending on the reaction temperatures and the ratio of zinc acetate/chitosan. The pores were created inside of the composites during the synthesis due to the degradation of chitosan at elevated temperatures. It was hypothesized that network formation is a possible first step in the synthesis. The formation of chitosan network during hydrothermal treatment was investigated at the different loadings and time. The samples were analyzed by SEM confirming the presence of foam structure. The antioxidant properties of the composites were evaluated by DPPH assay and TEAC assay. The radical scavenging activities of the composites have increased due to the successful transfer of chitosan’s antioxidant properties to ZnO upon covalent functionalization. In DPPH assay, ExZnO-CS synthesized at 180 °C in half volume (the amount of ZnO/CS was reduced by half while the solvent volume remained the same) showed greater scavenging activity than that of the samples synthesized in full volume. In TEAC assay, the composites synthesized at 180 °C showed better activity than those synthesized at 220 °C. Moreover, ExZnO-CS, regardless of the synthesis temperature and full/half volume, showed better scavenging activity compared to the other
composites. References 1. Natalia Sergeeva 2. School of Design, University of Leeds, Leeds, LS2 9JT, UK 3. N.Sergeeva@leeds.ac.uk
P20
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