Regarding the mechanical properties, the incorporation of nano-objects often results in an enhanced resistance to applied stress. This effect was evident in the higher strain values required for the hydrogel to undergo disruption and for G" to become greater than G' (i.e., flow point). While higher tensile strength is generally the result of an enhanced crosslinking density, an excessive level of crosslinking can reduce polymer chains flexibility making the material heterogeneous, or too brittle and reduce its ability to deform. In contrast, when crosslinking is moderate, polymer chains can slide during oscillation, thereby resulting in better dissipation and a higher flow point. Repeated exposure of hybrid hydrogels to strain cycles revealed their remarkable selfhealing capabilities. These materials turn into a liquid-like state when exposed to high strain, and quickly return to their original solid-like condition, with rapid restoration of G' and G" values upon strain reduction. Behind these healing properties lies a diversity of bonds present in the hydrogel network, encompassing dynamic covalent, hydrogen, π-π stacking, catechol-borate and electrostatic interactions. These bonds facilitate rapid structural reorganization and guarantee a consistent recovery process over several cycles (Figure ). Generally, the improvement in self-healing efficiency correlates with the content of nanoobjects. For example, it increased from 88 to 99% when the CNC amount was increased from 1 to 5% in PVA hydrogels. Conversely, incorporation of silica NPs into PEG hydrogel at concentrations above 7% resulted in a slight reduction in recovery, probably due to a too high NP content that interfered with the mass transfer. Copyright 2022 American Chemical Society. (b) Adapted with permission. Copyright 2019 The Royal Society of Chemistry.