In Situ Growth of Multiresponsive Structural Color Patterns within Hydrogels for Multiple Information Encryption.

Mimicking natural organisms to directly fabricate multiresponsive structural color patterns from small molecules is of great significance for information encryption but remains challenging. Herein, we present a bionic entanglement-interlocking microphase separation strategy for in situ growth of multiresponsive structural color patterns within hydrogel matrixes. The precursor solutions of common polymerization-induced phase-separated materials are used as small-molecule nutrients. The newly generated polymer networks can thus spontaneously collapse into phase-separated microspheres within hydrogels during polymerization. In particular, the dense internetwork entanglements form between the microspheres and hydrogel networks during phase separation, anchoring the microspheres firmly onto hydrogel networks to hinder their gathering. Consequently, these newly grown microspheres can be maintained at the desired nanoscale for yielding the structural blue color by light scattering. Multiresponsive schemochrome patterns can be readily created by growing different microspheres within hydrogel matrixes for multiple information encryptions. We demonstrate that this facile self-growth strategy is applicable to different polymerization-induced phase-separated materials and hydrogel matrixes, regardless of cross-linking modes and geometries.