Sub-nanometer nanowire-enhanced ultra-strong, eco-friendly and recyclable water-based adhesives

Abstract

Traditional adhesives face an enduring dilemma, that is, oil-based systems achieve high strength at the cost of volatile organic compound (VOC) emissions, while water-based alternatives suffer from inadequate performance. To resolve this paradox, a sub-nanometer filler-reinforced adhesive has been fabricated by integrating ultra-flexible gadolinium oxyhydroxide (GdOOH) nanowires (diameter < 1 nm) into a polyacrylic acid (PAA) aqueous matrix. The sub-nanometer dimensions and polymer-like flexibility of GdOOH nanowires enable uniform dispersion via dynamic hydrogen bonding, mechanical interlocking, and chemical anchoring, synergistically optimizing the cohesion-adhesion balance. With merely 1 wt% GdOOH loading, the lap shear strength surges by 285 % (3.96 MPa vs. 1.39 MPa for pure PAA), while retaining 75 % initial strength after 20 fatigue cycles, which is unprecedented for water-based adhesives. The composite demonstrates robust humidity (10–80 % RH) and temperature (−40 °C to 50 °C) adaptability, maintaining >1.5 MPa adhesion across diverse substrates (wood, metal, glass). Its reversible debonding via water-responsive hydrogen bond disruption, near-zero VOC emissions, and recyclability (95 % strength recovery) offer a sustainable paradigm. This "dynamic bonding–nano-interlocking" strategy bridges organic-inorganic interfaces, paving the way for high-performance, eco-friendly adhesives in automotive, electronics, and biomedical applications.