Birefringence effects in isotropic phases of Chromonics liquid crystals under confinement

Micro confinement of soft matter systems alters their self-assembly, changing thermodynamic and kinetic pathways and producing unique organizational motifs inaccessible in bulk. Understanding the mechanisms behind confinement-driven phase transitions in soft materials may enable the development of responsive systems whose properties can be dynamically tuned by spatial constraints, offering significant potential in applications such as stimuli-responsive drug delivery, soft robotics, and adaptive biomedical devices. The confinement of chromonic liquid crystals mesophases in spherical geometries has been widely studied in the past years but no data are present in literature concerning the confinement of their isotropic phase. In this work we report on the rise of a liquid crystalline phase in microspheres prepared by emulsifying an isotropic solution of chromonic liquid crystal in a polymeric immiscible matrix. Birefringence is observed at room temperature in a considerable percentage of microspheres whose textures are related to the microspheres' dimension. The phenomenon is general; it does not depend on the chromonic mesogen flexibility and it is not sensitive to the presence of ions.