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Title: Microfluidic Processes for Synthesis of Plasmonic Nanomaterials
Keywords: Microfluidics, Droplets, Compound drops, Plasmonic nanomaterials, Anisotropic gold nanorods, Gold nanoshells.
Issue Date: 7-Oct-2011
Citation: SUHANYA DURAISWAMY (2011-10-07). Microfluidic Processes for Synthesis of Plasmonic Nanomaterials. ScholarBank@NUS Repository.
Abstract: Plasmonic nanomaterials are at the forefront of current research in nanoscience due to their fascinating size- and shape-dependent optical properties. Such materials are most commonly synthesized via wet chemical solution-based methods that require precise control over reagent dispensing, mixing and particle growth. This thesis aims to develop continuous microfluidics-based processes that overcome the limitations of conventional methods and enable controlled wet-chemical synthesis of nanomaterials. The work in this thesis specifically focuses on two candidate materials - gold nanocrystals of varying shapes and sizes and metallodielectric gold nanoshells comprising of dielectric (silica) cores coated with thin gold shells. As a first demonstration, anisotropic gold nanocrystal dispersions were synthesized using a droplet microfluidic method. Synthesis experiments were performed using a well-established seeded growth protocol in which pre-synthesized gold nanocrystal seeds were used for the growth of anisotropic gold nanorods. A crucial limitation of this method was the batch-to-batch variations in the quality of the pre-synthesized seeds. A segmented gas-liquid flow method using nitrogen gas was developed for online chip-based seed synthesis using sodium borohydride as the reducing agent. The injected bubbles served as inert reservoirs for the transport of the released hydrogen from the aqueous reagent solution, thus completely preventing uncontrolled formation of hydrogen bubbles that could otherwise disrupt the flow. Integration of seed synthesis and subsequent growth of anisotropic nanocrystals on a single chip is currently underway. Finally, an interesting class of the three phase gas-liquid-liquid flows were introduced in this thesis, and used to demonstrate the synthesis of metallodielectric nanomaterials. Further, such flows enabled the use of reactive gases such as carbon monoxide as reducing agents in the synthesis of plasmonic nanomaterials.
Appears in Collections:Ph.D Theses (Open)

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