Self-healing polyurethane coating doubles corrosion resistance

Offshore wind power installations are exposed to extremely corrosive marine environments, placing high demands on protective coatings. While organic coatings remain a cost-effective approach, conventional single-functional systems often fall short of the combined performance requirements. A research team has now developed a multifunctional polyurethane (PU) coating that integrates self-healing capability, high mechanical strength and corrosion resistance in a single system.

The coating matrix, designated PU-SS-DA, was prepared by introducing bis(4-hydroxyphenyl) disulfide and furil as chain extenders, with bismaleimide serving as a cross-linking agent. This combination creates triple dynamic bonds within the polymer network, enabling the coating to achieve a tensile strength of 20.88 MPa and a toughness of 84.93 MJ/m³.

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Near-complete scratch repair at moderate temperatures

In scratch healing tests, the PU-SS-DA matrix demonstrated a self-healing efficiency of approximately 90 % after four hours at 80 °C. To further enhance both healing and anticorrosive performance, the researchers designed a functionalised boron nitride filler (Mi-hBN-OH) that strengthens the interfacial bonding between filler and coating matrix.

The resulting composite coating, PU@BN, containing 5 % Mi-hBN-OH filler, exhibited the highest impedance values among the tested formulations, reaching 3.23 × 10⁹ Ω·cm² initially. After 28 days of immersion in saline solution, the impedance at 0.01 Hz remained at 6.28 × 10⁹ Ω·cm² – effectively doubling the anticorrosive performance compared to conventional polyurethane coatings.

Synergistic approach for marine protection

The study demonstrates that the synergistic effect of multiple dynamic bonds combined with modified inorganic fillers can yield coatings that simultaneously address mechanical durability, autonomous damage repair and long-term corrosion resistance. This multi-functional design approach offers a viable pathway for next-generation protective coatings in demanding marine environments, particularly for offshore energy infrastructure where maintenance access is limited and lifecycle cost control is critical.

Source: Tang, A. et al., Self-healing polyurethane coatings with multi-dynamic bonds: Fabrication and applications. Progress in Organic Coatings 109932 (2025).

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