Ambient Cross-linking System Based on the Knoevenagel Condensation Reaction between Acetoacetylated Sucrose and Aromatic Dicarboxaldehydes

Abstract

An ambient cross-linking system based on the Knoevenagel condensation reaction between acetoacetylated sucrose and aromatic dicarboxaldehydes was demonstrated. In this study, we use a rheological instrument to measure the gel time to predict and elucidate the likely reaction mechanism of the system, and we prepare films based on the mechanistic results. Acetoacetylated sucrose and 4,4′-biphenyldicarboxaldehyde were used as raw materials, piperidine was used as the catalyst, and nonvolatile dimethyl sulfoxide (DMSO) was used as the solvent. After mixing 4,4′-biphenyldicarboxaldehyde and piperidine for 30 min, the acetoacetylated sucrose was added, thus producing the shortest gel time. Then, the gel was characterized by Fourier transform infrared spectroscopy. In addition, three films were prepared by this approach with different aromatic dicarboxaldehydes, and the properties of the coatings were characterized by differential scanning calorimeter, dynamic mechanical analysis thermogravimetric analysis, and swelling ratio. It was found that these films have high Young's modulus, high glass transition temperatures, high pencil hardnesses, and low swelling ratios.