Size-Selective Exclusion Effects of Liquid Crystalline Tactoids on Nanoparticles: A Separation Method

Liquid crystalline tactoids are anisotropic microdroplets existing in isotropic phases. We studied the structure and evolution of tactoids in the presence of doping nanoparticles by electron microscopy at the resolution of individual mesogens and observed size-selective exclusion effects of liquid crystalline tactoids on foreign nanoparticles. We applied this principle to the separation of polymer nanospheres, gold nanoparticles, and magnetic nanoparticles by size. These results indicate a new way to size-selectively separate nanoparticles using lyotropic liquid crystals, in which nanoparticles smaller than a threshold size will be selectively transferred from the disordered phase into the ordered phase by tactoids during the phase separation process.