Mechanically robust and self‐healing waterborne polyurethane nanocomposites based on inorganic organic hybrid materials and reversible covalent interaction

Endowing waterborne polyurethane (WPU) materials with mechanically reinforced and self‐healing property is a pressing issue for expanding practical applications. In this article, we proposed a simple method to give WPU with self‐healing properties while improving the mechanical properties. First, furfuryl‐modified silica nanoparticles (furan@SiO2) with high functionality and excellent dispersibility were prepared by the sol–gel method. Furan@SiO2 was then introduced into the side‐hanging maleimide WPU to form a thermally reversible inorganic–organic network (WMSPUS‐x) based on the Diels‐Alder reaction. The morphologies and properties of furan@SiO2 and WMSPUS‐x emulsions were analyzed by TEM and DLS, demonstrating the excellent dispersion of furan@SiO2 and the storage stability of emulsions. The cross‐linking density of the nanocomposites was varied by the furan@SiO2 contents, and the effects of cross‐linking density on mechanical and self‐healing properties were systematically investigated. In addition, the thermal stability of WMSPUS‐x nanocomposites was significantly improved shown by TGA results. Finally, qualitative and quantitative studies of the self‐healing process were carried out to verify that WMSPUS‐x nanocomposites possess great self‐healing capacity. The outcomes indicate that WMSPUS‐x nanocomposites have great potential for application as a smart material.