On mechanical properties of nanocomposite hydrogels: Searching for superior properties

Nanocomposite hydrogels are the combination of known components that are a hydrogel and nanometre-sized fillers, typically leading to improved mechanical properties or new functionalities. With simplicity of design and ease of synthesis, recent advances have highlighted that this family of hydrogels holds the significant promise of application in diverse biomedical and engineering fields. The elaborate design and investigation as well as suitable application of nanocomposite hydrogels require the synergy of mechanics, materials science, engineering, and biology. Despite similarities in design and fabrication, the data of mechanical properties for nanocomposite hydrogels scatter in a large space. It is worthwhile comparing various nanocomposite hydrogels for similarities and differences in mechanical properties to aid in designing novel hydrogels with extreme properties, and guide practical applications. This review aims to fill, in the literature, the missing gap of addressing mechanical measurement methods and comparison of mechanical properties in this ever-evolving broad area of research. Finally, the challenges and future research opportunities are highlighted.