Effect of the type of reducing agents of copper ions in interpolyelectrolyte-metal complexes on the structure and properties of copper-containing nanocomposites

The structural features, thermomechanical and electrical properties of copper-containing polymer nanocomposites formed by chemical reduction of copper ions in interpolyelectrolyte-metal complexes like pectin-Cu2+-polyethyleneimine with the use of various reducing agents (sodium borohydride, hydrazine, and ascorbic acid) are investigated. X-ray diffraction analysis reveals that the use of NaBH4 and C6H8O6 reducing agents results in formation of nanocomposites with Cu/Cu2O "core-shell" nanoparticles, while when using N2H4 as a reductant, nanocomposites with only metallic copper nanoparticles are formed. Thermo-mechanical analysis shows that the reduction process becomes more efficient with increasing in the molar ratio of (NaBH4 or C6H8O6):Cu2+ from 2 to 6, whereas, in the case of N2H4, complete reduction occurs already at a molar ratio of N2H4:Cu2+ = 2. Copper-containing nanocomposites formed by NaBH4 and N2H4 are established to exhibit semiconductor properties, whereas the initial interpolyelectrolyte complexes and nanocomposites prepared with C6H8O6 are typical dielectrics.