A cross-linker containing aldehyde functionalized ionic liquid for chitosan

The synthesis of conductive and eco-friendly new chitosan composite biopolymer with a novel aldehyde functionalized ionic liquids (AFILs) was investigated in this work. The AFILs, 1,1′-(pentane-1,5-diyl) bis(4-formylpyridin-1-ium) dibromide (C₅PyBr), 1,1′-(octane-1,8-diyl) bis(4-formylpyridin-1-ium) dibromide (C₈PyBr) and 1,1′-(decane-1,10-diyl) bis(4-formylpyridin-1-ium) dibromide (C₁₀PyBr) have been synthesized and they were characterized by FT-IR, UV–vis and ¹H-NMR and ¹³ C-NMR, TG, and DSC analyses. The synthesized AFILs, C₅PyBr C₈PyBr and C₁₀PyBr were used as cross-linker for chitosan biopolymers and the cross-linked chitosan composites, chitosan/1,1′-(pentane-1,5-diyl)bis(4-formylpyridin-1-ium)dibromide (Ch/C₅PyBr), chitosan/1,1′-(octane-1,8-diyl)bis(4-formylpyridin-1-ium)dibromide (Ch/C₈PyBr) and chitosan/1,1′-(decane-1,10-diyl)bis(4-formylpyridin-1-ium)dibromide (Ch/C₁₀PyBr) were prepared. Herein, the synthesized AFILs have not only cross-linked chitosan, but also provide them the desired novel, functional groups. The prepared chitosan composites were characterized by FT-IR for the analysis of structural, TG and DSC for the thermal behavior, and an electrometer for the electrical conductivity. The electrical conductivity of the prepared Ch/C₅PyBr composite was measured as 1.69?×?10^?5 ± 2.37?×?10^?5 S cm^?1 by the four-point probe at room temperature and this value is higher about 4500-fold than the electrical conductivity of the chitosan.