Waterborne polyurethane porous coatings enabled by Pickering aqueous foam templates for sustainable synthetic leather manufacturing

The adoption of waterborne polyurethane (WPU) as a substitute for solvent-based polyurethane offers a sustainable solution for synthetic leather production. However, the foaming technology for such coatings remains a challenge. Herein, we explore the development of ultra-stable Pickering aqueous foams co -stabilized by waterborne polyurethane (WPU) and hydrophilic SiO 2 particles (N20) as templates for the fabrication of WPU porous coatings. The results reveal that both WPU and N20 not only enhance interfacial elasticity but also form a gel-like network in the continuous phase via hydrogen bonding, thereby improving foam stability even at 120 °C. The microstructure and properties of the porous coatings are readily tailored by adjusting the N20 content. A porous coating (WPU@N20-3), templated from an aqueous foam co-stabilized by 40 wt% WPU and 3 wt% N20, exhibits a well-defined and interconnected porous morphology, along with high thermal stability (T 5% = 275.8 °C), a tensile strength of 9.3 MPa, and an elongation at break of 322 %. The resulting WPU-based synthetic leather demonstrates superior softness (8.4 mm), rebound resilience (317 ms), and water-vapor permeability (952 g/m 2 ·d) compared to solvent-based PU synthetic leather. Furthermore, the production process eliminates VOC emissions, solvent usage, and associated recovery energy consumption. This work presents a sustainable strategy for producing high-performance synthetic leather, promoting a paradigm shift toward green manufacturing. • Ultra-stable Pickering aqueous foams are constructed using WPU and hydrophilic SiO₂ as co-stabilizers. • Ultra-stable Pickering aqueous foams are developed to prepare WPU porous coatings • WPU-based synthetic leather shows better softness, resilience, and breathability. • The production process is environmentally sustainable.