Switchable whiteness in liquid crystal networks via solvent-induced microphase segregation.

Dynamic control over optical whiteness is promising for applications ranging from energy-efficient coatings to adaptive displays. However, current approaches rely on macroscopic structural transformations or externally imposed refractive-index contrasts, offering limited tunability and scalability. Here, we introduce a liquid crystal network (LCN) that undergoes reversible whitening through solvent-triggered disruption of supramolecular interactions. Exposure to polar protic solvents breaks hydrogen bonds and drives nanoscale phase segregation, generating domains that efficiently scatter visible light. This whitening mechanism enables rapid, robust, and fatigue-resistant switching, with scattering efficiencies exceeding 90% in 100 μm LCN films. By tailoring the molecular design, incorporating halogen-bonding dopants, and post-treatment with acid or base, the optical contrast and switching kinetics can be tuned. We demonstrate potential applications in biometric pattern recognition, underwater visibility enhancement, and solvent discrimination, establishing a materials platform towards dynamic scattering materials.