High Biobased Carbon Content Polyurethane Dispersions Synthesized from Fatty Acid-Based Isocyanate

Abstract

A series of high biobased carbon content polyurethane dispersions (PUD) was successfully synthesized from dimer fatty acid diisocyanate (DDI), castor oil (CO), alkoxysilane-modified castor oil (MCO), and dimethylolpropionic acid (DMPA). This work focused on the improvement for the final performance of the renewable DDI-based PUD as well as the discussion of structure/property relationships. The chemical structure of MCO and Si–O–Si cross-link network structure on the dry-film of PUD were characterized by Fourier-transform infrared spectroscopy (FTIR) and solid-state 29Si NMR. The effect of alkoxysilane and NCO/OH ratio on DDI-based PUD were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile tests, and electrochemical impedance spectroscopy (EIS). The glass transition temperature, Young’s modulus, and tensile strength increased with the incorporation of alkoxysilane and increasing NCO/OH ratio. In the meanwhile, the initial degradation temperature and elongat...