Programmable Mechanochromic Time Integrators

Abstract

AbstractMechanochromic polymers are receiving much attention for monitoring the structural performance of materials. Current mechanochromic polymers however do not offer simultaneous detection of the duration and degree of strain while retaining memory of the strain history. Here a structurally colored polymer coating is reported that can indicate, quantify, and memorize strain over time. The mechanochromic polymers are fabricated by a simple and scalable bar coating process. The coating consists of chemically and optically distinct cholesteric liquid crystal droplets. Upon strain, the droplets deform causing an eye‐discernible reflective color change through a diffusion‐based compositional ripening process. The response depends on both the degree and duration of strain and can be easily adjusted by the concentration of droplets in the coating. The programmable mechanochromic time integrator offers simultaneous and sensitive detection of strain over a wide range while exhibiting memorability. The user‐interactive interface allows people to visually perceive the strain history of materials and introduces a novel mechanochromic material for monitoring the structural performance of materials ultimately enhancing both safety and performance.