Michael Addition Inducing Self‐Assembly to Construct Mechanochromic BP Film

Liquid crystalline blue phase (BP) with 3D cubic nanostructure has attracted much interest in the fields of photonic crystals due to their unique optical properties and the ability to control the flow of light. However, there remains a challenge for simultaneously achieving self‐assembly and mechanochromic response of soft 3D cubic nanostructures. Herein, a scalable strategy for the preparation of soft 3D cubic nanostructured films using oligomerization of the Michael addition reaction, which can induce the assembly of double‐twisted cylinders for collective replication, remodeling, recombination, and growth, with a phase transition from BPII to BPI, and to chiral nematic phase, is presented. The prepared BP patterns can be obtained by Michael addition oligomerization reaction and composite mask photopolymerization, which present distinct mechanochromic sensitive due to patterns derived from different BP state, and the pattern can be reversibly erased and recurred by mechanical force and temperature. The average domain size of BPII prepared using this strategy can achieve 96 µm, which is 2.5 times larger than that obtained using the conventional cooling approach. This work provides new insights into the self‐assembly and selective chemochromism of functional materials and devices. Functionalized films with large‐domain BP are fabricated successfully by oligomerization of the Michael addition reaction, which can be used to compile the crosslinking density and functions of polymers and can be patterned and “frozen” by the UV polymerization at any time. The as‐fabricated patterns can be reversibly erased and recurred by mechanical forces and temperature, presenting the distinct mechanochromic sensing.