SYNTHESIS AND PROPERTIES OF POLYIMINES BASED ON DIALDEHYDES OF THE FURAN SERIES AND VARIOUS DIAMINES

In this work, the reactions of 2,5-diformylfuran (DFF) with various aromatic and aliphatic diamines were studied, and the physicochemical properties of the resulting polyimines were studied. Research on the synthesis of electro-conductive polymers and the study of their physicochemical properties attracts great interest in modern polymer science. A class of electrically conductive polymers that has been particularly attractive for research in the last half century are aromatic polyimines, which are also known as polyimines or Schiff-based polymers. DFF-based polymers are little studied due to the high cost of the monomer, which limits its synthetic application. The availability of DFF is made both by the development of economical methods for its production, the oxidation of 5-hydroxymethylfurfural (5-HMF), and by the provision of sustainable access to 5-HMF from biomass. Polyimines containing furan fragments were synthesized by low-temperature poly-condensation of DFF, available from plant materials, and various aromatic diamines in ethanol. The resulting polymers were high-melting thermoplastics from yellow to orange. The polymers showed typical absorption bands characteristic of the stretching vibrations of the C=N group (about 1620 cm(-1)) in the infrared spectra and had high glass transition temperatures of more than 200 degrees C. The ionic conductivity of polyimines has been characterized by electrochemical impedance spectroscopy. The conductivity value for polyimines, doped with I-2, reaches 1.24.10(-4) S cm(-1) (at 298 K and 100% relative humidity), which is one of the highest values of proton conductivity for polyimines doped without using metals or their salts. The resulting polymers can be used to manufacture composites with various fillers.