Optimized One-Pot reaction and characterization of a cyanoethoxyethylated chitosan

Chitosan offers a wide range of applications due to its reactive amino groups, which enable various modifications. This study presents the synthesis of a chitosan derivative (ChECEA) using ethyl 2-cyano-3-ethoxyacrylate (ECEA). The reaction was conducted under various conditions to optimize the mass gain of the ChECEA. Stoichiometry (1.5 and 2.0M), temperature (60 to 95 °C), and reaction time (1 to 3.5 h) were varied. The ChECEA was characterized using a variety of techniques, including Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), Thermogravimetry (TG), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Zeta Potential, Contact Angle (CA), and Elemental Analysis (EA). FTIR confirmed the successful modification, evidenced by a sharp peak at 2220 cm^-1 corresponding to the CN bond stretching. NMR analysis revealed new chemical shifts (166, 158, 115, and 11 ppm), and in combination with EA, was used to estimate the degree of substitution (DS) as 0.640 and 0.725, respectively. TG indicated a decrease in thermal stability and Zeta Potential suggested reduced suspension stability. Conversely, contact angle measurements showed increased hydrophobicity and decreased surface energy. Finally, XRD analysis revealed a decrease in the crystallinity index (from 79 % to 55 %), likely due to the incorporation of cyanoethoxyacrylate groups.