Bio-based polyurethanes: Enhanced corrosion protection and luminescence through fluorescent azine segments

A research team led by Marwa M. Sayed has developed novel bio-based polyurethanes (PUHs) derived from castor oil, featuring improved luminescence and outstanding corrosion protection for mild steel. The polyurethanes were synthesised by reacting castor oil polyol (COP) with hexamethylene diisocyanate (HMDI) and fluorescent azine segments, such as 1,4-phenylene bis(2,4-dihydroxy benzylidene) azine (PDaz) or modified epoxy castor oil (Eaz).

The physical and chemical properties were analysed using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The resulting PUHs exhibited high yields, strong photoluminescence and efficient corrosion inhibition. By modifying the preparation strategy, the researchers were able to control both the intensity and wavelength of the emitted light.

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Effective corrosion protection using bio-based materials

The best performance was achieved by PUH3, which demonstrated a corrosion inhibition efficiency of 97.6 %. The compounds act as mixed-type inhibitors, effectively protecting mild steel surfaces while providing high mechanical strength and optimal adhesion. These results point to promising applications for these PUHs in luminous, corrosion-resistant coatings – particularly in areas where both optical and protective functions are required.

Source: Progress in Organic Coatings, Volume 200, March 2025, 109051

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