Regioselective Synthesis of 6-Triphenylmethyl-2,3-hydroxypropyl Cellulose and Its Application in Colorless Anticounterfeiting Labels

This work demonstrates a regioselectively designed cellulose derivative that enables colorless liquid-crystal-based anticounterfeiting with polarization-dependent readout. To overcome the intrinsic visibility and color dependence of conventional optical anticounterfeiting technologies, the hydroxyl group at the C6 position of cellulose was first selectively protected with trityl chloride, followed by ring-opening etherification of the C2 and C3 positions with propylene oxide to yield structurally defined 6-triphenylmethyl-2,3-hydroxypropyl cellulose (6T-HPC). A systematic comparison between 6-triphenylmethyl cellulose and its hydroxypropylated derivatives reveals that 6T-HPC retains liquid-crystalline ordering while completely suppressing visible structural color, thereby achieving an effective decoupling of liquid-crystal optical response from photonic-crystal coloration. Due to this unique optical behavior, a colorless liquid-crystal anticounterfeiting label was fabricated. The label remains fully transparent and invisible under ambient light, yet displays predefined patterns and optical textures when viewed under polarized conditions, enabling a “covert storage-polarized readout” mode of information encoding. This work demonstrates a precise molecular design strategy for tuning the optical functionality of cellulose derivatives and establishes a new route toward sustainable, high-security, and difficult-to-replicate colorless anticounterfeiting materials.