Robust superhydrophobic polyurea composite coating with octadecyltrimethoxysilane -modified halloysite nanotubes: Hierarchical design for mechanical and chemical durability in harsh environments

A superhydrophobic composite coating with exceptional durability was fabricated by integrating octadecyltrimethoxysilane (ODTMS)-modified halloysite nanotubes (HNTs) into a polyurea (PU) matrix. The hierarchical micro-nano structure, constructed through hydrogen bonding networks between PU and HNTs, synergized with the low surface energy of ODTMS to achieve a water contact angle of 157°. Fourier-transform infrared spectroscopy, X-ray powder diffractometer and X-ray photoelectron spectroscopy analyses confirmed successful ODTMS grafting and homogeneous dispersion of HNTs within the PU matrix. Remarkably, the coating retained superhydrophobicity (contact angle >150°) after 50 tape-peeling cycles and 130 cm sandpaper abrasion, attributed to the dual reinforcement mechanism of PU's elasticity and HNTs' mechanical robustness. Furthermore, the coating exhibited pH stability (pH 2–12 for 20 h) and thermal resistance up to 250 °C. This work provides a scalable strategy for designing durable superhydrophobic coatings, demonstrating potential applications in construction, ships, and electronic devices under extreme conditions.