High-strength and self-healing bio-based polyhydroxyurethanes for high-temperature adhesives

Polyhydroxyurethanes (PHUs) are considered a sustainable and safe alternative to traditional isocyanate-based polyurethanes (PUs). A recent study shows that a strong and rapidly self-healing bio-based PHU network has been developed based on carbonated daidzein (DZ-BCC) and amines.

The use of amino-propyl-terminated polydimethylsiloxane (H2N-PDMS-NH2) as a soft segment increases chain mobility and thus optimises the self-healing properties. At the same time, the high crosslinking density of the network together with the benzopyran ring structure of the daidzein ensures an impressive mechanical strength of up to 28.3 MPa.

Event Tip: Bio-based Coatings

In the EC Short Course “Bio-based Coatings” on March 17, 2025 (online, 15:00 – 17:00 CET), you will learn about plant-based raw materials in coatings, their production, and the challenges of replacing fossil-based materials. The course provides insights into sustainable alternatives and their impact on the industry.

Rapid self-healing and high temperature resistance

Despite this high mechanical stability, the materials show remarkable self-healing: after only 30 minutes at 150 °C, 94% of the original tensile strength can be restored. In addition, these PHU-based materials can be used as adhesives for wood and glass bonding, with shear strengths of up to 6.4 MPa and 3.4 MPa, respectively.

Another advantage is their temperature resistance: bonded glass samples remain stable even at 150 °C. Chemical recyclability and high reprocessability also make these materials particularly attractive for sustainable applications.

Conclusion

The daidzein-based PHUs presented combine high strength with rapid self-healing, thus expanding the range of applications for sustainable high-performance adhesives. Their special properties could create new possibilities for high-temperature bonding in the wood and glass industries.

Source: Jie Liu et al., Polymer Chemistry, Issue 7, 2025.