Multiresponsive Isotropic Structural Color in Cholesteric Liquid Crystals

Cholesteric liquid crystals (CLCs) are promising photonic materials due to their tunable Bragg reflection. However, their practical implementation remains constrained by a fundamental trade-off: planar CLC films suffer from intrinsic viewing-angle dependence, whereas CLC emulsions remain restricted in responsiveness and macroscopic processability. Here, we address this limitation by developing multiresponsive CLC emulsion-based materials that generate isotropic (angle-independent) structural color through radial helical organization. A reactive CLC formulation was optimized to incorporate functional motifs responsive to temperature, chemical analytes, and light. The resulting droplets are embedded within a polymer matrix to yield mechanically robust films and printable inks that retain tunable Bragg reflection while suppressing angular color dispersion, enabling clearly discernible macroscopic coloration. These materials can be cast into molds, directly written, or brush-coated onto arbitrary substrates, allowing patterned coatings and three-dimensional architectures with preserved optical response. Across all formulations, distinct and reversible reflection-band shifts are observed under external stimuli, demonstrating that cholesteric pitch modulation is preserved under confinement. This strategy establishes polymer-embedded CLC droplets as versatile, multiresponsive photonic building blocks and offers a generalizable route toward processable, isotropic structurally colored materials capable of translating environmental inputs into accessible optical signals.