Synthesis and characterization of polyphenol-based polyurethane

A novel adhering polyurethane (PU), based on hydrolysable tannins that contain a number of active sites, was successfully synthesized and characterized. The active sites were catechol groups in the hydrolysable tannins, which were used as a substitute for dopamine. This efficient, universal, and low cost coating based on hydrolysable tannins was cured by adding FeCl3, and was evaluated by nuclear magnetic resonance (1H-NMR), Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and UV-Visible spectrophotometry (UV/Vis). The polyurethane coating containing tannins showed improved coating adhesion and an accelerated curing rate on the substrate, both of which were similar those of dopamine based PU coatings. The TGA and UV/Vis results indicated that the characteristics of the tannin-containing polyurethane were deeply related to the concentration of the tannins.