| dc.description.abstract | This dissertation research investigates two-dimensional (2D) nanoparticles, their synthesis, characteristics, function and performance. The 2D nanoparticles, as a novel class of materials, have attracted significant interest in last two decades. With the development of synthetic technology, many 2D materials like graphene, MXenes, transitional metal dichalcogenides, boron nitride, black phosphorus, and emerging hybrid materials have been developed and achieved more complicated structures. The 2D particles possess distinct properties like low-dimension, ultrathin thickness, and large surface areas. The controlled self-assembly of 2D materials enabled additional functions and device fabrication. In particular, colloidal suspension of 2D materials displays a plethora of liquid crystal phases including isotropic, nematic, smectic due to self-assembly variance. Liquid crystal is an intermediate state between liquids and solids, which has relatively ordered arrangements and flows like a fluid. The direct optical visualization of 2D liquid crystals is incredibly beneficial to investigate the real-time self-assembly and orientation of 2D colloids. Therefore, investigation of 2D colloidal liquid crystals, accompanying the control of structure, self-assembly and phase transition property, has become the critical influencing aspect in 2D materials.
In this dissertation, 2D nanoparticle zirconium phosphate (ZrP) has been chosen as a model for investigating the nanoplate liquid crystal phase transition behaviors. We investigate 2D materials’ structure, processing and optical performance relations. ZrP is working as a template particle due to its high shape anisotropy, controlled morphology, small polydispersity and high diameter-to-thickness ratio. The self-assembly of ZrP liquid crystals is affected by internal properties and external fields at the same time.
We use an experimental approach to study controlled self-assembled 2D nanoparticle liquid crystals. It includes four major activities: synthesis of 2D ZrP crystals and liquid crystals; development of aspect ratio dependence of liquid crystal phase transition; investigation of the temperature field dependence of liquid crystal phase transition; study the concentration dependence of nematic liquid crystal photonic applications. The ZrP liquid crystal phases are found to be precisely tuned through aspect ratio, temperature and concentration. The self-assembly controlled 2D ZrP colloids will facilitate understanding the processing and performance of 2D materials in diverse areas like photonics, energy storage, sensors and electronics. | |
