4-(Benzimidazolisonitrosoacetyl)biphenyl modified chitosan and its copper complex: Synthesis and electrorheological properties

A novel chitosan Schiff base derivative (CsB) was synthesized for the first time by a condensation reaction of chitosan with 4-(benzimidazolisonitrosoacetyl)biphenyl. As a result of the coordination reaction of copper ions, its copper(II) complex (CsBCu) was constructed. Then, the structures were confirmed by ICP-OES, ATR-FTIR, TG/ DTA, and SEM analysis. Furthermore, electrorheological (ER) properties of the synthesized compounds, as a new dry-based ER fluid, were extensively studied in silicone oil (SO). CsBCu/SO exhibited a higher shear stress value of 78 Pa at a 2.5 kV mm-1 applied electrical field than Cs/SO and CsB/SO, which is attributed to the contribution of the paramagnetic nature of the Cu element. The shear and oscillation tests revealed ER and viscoelastic behavior of the suspensions upon applying an external electric field (E).