Self-assembly of metal oxide nanoparticles into hierarchically patterned porous architectures using ionic liquid/oil emulsions

Hierarchically patterned macroporous TiO ₂ structures can be fabricated via the spontaneous self-assembly of TiO ₂ nanoparticles prepared using a mixture of 1-octadecene (ODE) and an ODE-immiscible l-alkyl-3-methylimidazolium-based ionic liquid as the reaction medium. A study of the influence of side chain lengths of ionic liquids (n = 4, 8, or 16) reveals that this parameter can be further used to fine-tune the morphologies of the products. This synthetic methodology can also be extended to the formation of patterned macroporous ZrO ₂ and Fe ₃O ₄ structures. Finally, the potential reasons for the formation of hierarchical structures are discussed and the implications to further research are proposed.