Conductive Superhydrophobic Smart Coatings Based on Spherical Silver Nanoparticles and Waterborne Polyurethane for Flexible and Wearable Electronics

The development of flexible smart conductive fabrics is crucial for applications in smart healthcare and signal transmission during hazardous rescue operations. However, environmental challenges such as moisture, dirt, mechanical abrasion, and bacteria can significantly impair their electronic performance. Herein, we introduce a novel two-layered coating strategy that integrates silver nanoparticles (Ag NPs) and modified silica nanoparticles (QSi) with waterborne polyurethane (WPU) to develop multifunctional superhydrophobic conductive coatings. The inner composite layer, combining WPU with Ag NPs, guarantees high conductivity (5.22 S·cm^-1) and mechanical durability. The outer shell layer, created by spraying a mixture of WPU and QSi, provides a robust superhydrophobic barrier, maintaining a water contact angle above 150° and resistance below 80 Ω even after 200 kneading cycles. Additionally, the coated fabric exhibits satisfactory self-cleaning, antifouling, low water adhesion (32.95 μN), drag reduction (supporting approximately 11 times its weight on water), and appreciable antibacterial activity (>99.99%), ensuring its long-term stability in harsh conditions. By integrating conductivity with superhydrophobicity, flexibility, and wearability, this smart fabric presents a promising strategy for precise underwater detection, such as monitoring swimming movements or finger bending, while also offering safety alert signals in challenging wet environments.