Researchers from China's Northeastern University, Shenyang Jusheng New Material Technology, Key Laboratory of Medical Image Computing, Shenyang Aerospace University and Australia's University of New South Wales have developed a polyurea-based nanocomposite spray sensing coating reinforced with covalently functionalized graphene nanoplatelets, offering a scalable solution for structural health monitoring in demanding environments.
Preparation and Main Properties of Graphene NanoPlatelet-functionalized Polyurea Coatings.
Structural health monitoring (SHM) in harsh and complex conditions remains challenging, as conventional sensors often lack conformability, mechanical durability, and long-term stability. In their recent study, the team outlines a new approach - a spray-applied polyurea nanocomposite sensing coating that integrates functionalized graphene nanoplatelets to combine robust mechanical performance with reliable, real-time damage and strain monitoring for infrastructure and automotive structures.
“Our work introduces a spray-applied polyurea-based nanocomposite sensing coating that integrates covalently functionalized graphene nanoplatelets into a two-component polyurea matrix—improving processability for scalable deployment, enhancing weatherability for long-term outdoor service, and establishing a robust conductive network that delivers strong, reliable resistive sensing,” explains corresponding author Qingshi Meng, a professor of aerospace engineering at Shenyang Aerospace University.
The research introduces hexamethylene diisocyanate trimer-functionalized graphene nanoplatelets (HT‑GNPs) into a fast-curing, two-component polyurea matrix. The covalent functionalization facilitates uniform filler dispersion and enables chemical integration into the polymer network during spray curing. This molecular “anchoring” strengthens the hydrogen-bonded microstructure and forms a stable, low-threshold conductive pathway even under rapid gelation.
The resulting coating demonstrates exceptional mechanical performance—tensile strength of 43.4 MPa and elongation at break of 707.8% at 0.1 vol% HT‑GNPs. The optimized 2 vol% formulation achieves balanced performance with gauge factors of 8.4 (0–235% strain) and 16.0 (>235% strain), rapid response (88 ms) and recovery (92 ms), strong adhesion to diverse substrates, and stable operation after damp-heat, salt-spray, and UV-aging tests. Electrochemical analysis further confirms superior corrosion resistance, with corrosion potentials of 0.23 V (H₂SO₄), 0.12 V (NaOH), and 0.15 V (NaCl).
“Until now, scalable strain-sensing coatings have often faced a trade-off between easy spray processing, long-term weather resistance, and reliable electromechanical performance,” Meng notes. “By using covalently functionalized graphene to build a stable conductive network within a sprayable polyurea, we show these requirements can be met simultaneously.”
The authors emphasize that coupling interfacial molecular engineering with scalable spray processing offers a powerful pathway to creating resilient, multifunctional, and graphene-integrated sensing coatings. “We hope our results encourage wider exploration of molecularly engineered nanofillers to create durable, multifunctional coatings for infrastructure and automotive health monitoring,” the team concludes.
