Ultra-tough, strong and transparent bio-based waterborne polyurethanes with exceptional anti-corrosion properties

Waterborne polyurethane (WPU) is increasingly favored because of its affordability, eco-friendliness, and water-based storage convenience. However, the inclusion of hydrophilic groups can diminish its mechanical strength and water resistance. Herein, a range of bio-based waterborne polyurethanes were synthesized by using economical and sustainable poly(trimethylene ether) glycol (PO3G), isophorone diisocyanate (IPDI), and poly(propylene glycol) (PPG) as raw materials. They exhibited superior mechanical properties, transparency, and corrosion resistance. We explored the effect of PO3G content on the properties of these bio-based WPU emulsions and films. The findings revealed that films with over 30 % PO3G content demonstrated a high tensile strength (above 10 MPa) and maintained a high elongation at break (above 4000 %), matching or surpassing existing bio-based WPU systems. The corrosion resistance of these films was also exceptional, with a high inhibition efficiency (above 99.97 %). This research introduces a new approach for creating high-performance bio-based WPUs with promising applications in coatings, leather, and biomedical materials.