Figure 4.

(a) Schematic representation of the formation of the interfacial layer through the diffusion of monomers and cross-linkers. (a-1) Designed curvature in the absence of the interfacial layer formation, (a-2) Experimental curvature observed after the interfacial layer formation. (b) Simulation of the radius of curvature was conducted by varying the expansion ratio and the thickness of the interfacial layer in the hydrogel. The arrow marks the experimental radius of curvature of the bi-layered hydrogel, which was prepared with the composition of BH-3.