Chromonic Liquid Crystals as Dynamic Cross-Linkers inHydrogels

摘要

Lyotropic chromonic liquid crystals (LCLCs) are a class of lyotropic liquid crystals(LLCs) and popularly found in drugs,food dyes,and nucleic acids.They are typicallyformed by plank-like molecules with polyaromatic cores and ionic peripherals and whendissolved in a solvent,normally water,they stack into rod-like aggregates rather thanassembling into symmetric spherical micelles as in conventional lyotropic systems (Fig.1).The stacking of these so-called chromonic molecules is driven by the van der Waals force(π-π stacking) between the aromatic cores and the nanoseparation between hydrophilicgroups and hydrophobic groups.Unlike micelles,the chromonic aggregation process doesnot require a critical concentration.The aggregates form,grow and align with one anotherin water to form the nematic (N) phase with long-range orientational order,depending onthe concentration and temperature.The columnar (M) phase with long-range positionalorder may sometimes appear with further increasing the concentration,but still below thesolubility limit of the chromonic compound.LCLCs have been the subject of specialinterest in recent years because of potential applications in E-type polarizers,opticalcompensators,biosensors,medical diagnostic tools,and so forth.