Center for Functional Nanomaterials Seminar

Colloidal manipulation of nanomaterials is of particular importance to both low-cost device fabrication and the investigations of many fundamental issues such as colloidal interactions, crystal growth, and phase transition. We have studied three model nanomaterials: 0-dimensional quantum dots (QDs), 1-dimensional carbon nanotubes (CNTs), and 2-dimensional alpha-zirconium phosphate (ZrP) nanoplatelets. We have achieved the stable dispersion of these nanomaterials down to individual level in various media and their self-assembly into ordered structures. This presentation will focus on the self-assembly of these model nanomaterials into colloidal crystals or liquid crystals. In particular, i) optically-clear QD colloidal crystals are prepared through tuning colloidal interactions such as electrostatic screening. ii) Alignment and placement of individual CNTs are achieved through a guided self-assembling method by integrating the nano-imprinting technology. A direct self-assembly of CNTs into the liquid-crystalline nematic structure has also been found. iii) Discotic liquid-crystalline phase transition is studied using synthetic ZrP nanoplatelets. Nematic and smectic phases are found to be readily formed by manipulating the characteristics of the nanoplatelets such as diameter, thickness, polydispersity, and aspect ratio. The potential applications of these ordered structures will also be addressed.