Figure 4.

The practical application of hydrogels in wet adhesion involves complex interactions that can be divided into three main categories: chemical, physical, and bionic structural factors. (a) Chemical factors, such as catechol chemistry, in situ activation, and reactions of intrinsic groups of the material. (b) Physical factors, such as hydrophobic aggregation, physical entanglement, and energy dissipation. (c) Biomimetic structural factors, such as micro-patterning and capillary forces. Figure modified from [43] with permission.