SILICA SYNTHESIS & COATING OF QUANTUM DOTS IN DROPLET BASED MICROREACTORS

Date

2015-01-01

Author

Ozkan, Alican
Keleştemur, Yusuf
Demir, Hilmi Volkan
Erdem, E. Yegan

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We present a microfluidic reactor that utilizes meandering microchannel shape to mix reagents inside droplets in a carrier fluid to synthesize silica and silica coated nanoparticles. Meandering channels decrease mixing time due to reduced diffusion lengths. Moreover; droplet-based flow provides uniform reaction times due to the circulating flow profile inside droplets as opposed to parabolic flow profile in straight channels. Before fabricating our device, we have simulated the mixing performance of droplets at different channel cross-sections and meandering geometries using Comsol Multiphysics(C). As a result, we have concluded that channel cross-section and meandering dimensions should be as small as possible for faster mixing. Accordingly, we have fabricated our device in PDMS by using soft lithography technique and introduced chemicals to the microsystem by using syringe pumps. We will use this system to understand the effect of solvent concentration and residence time on silica formation to obtain better coating thickness distribution than in batch-wise methods. As a preliminary study, we tested the silica formation inside droplets and we obtained 102 nm 4 nm of silica nanoparticles. In the synthesis we followed a modified method of synthesis in the literature where droplets of solution composed of 20 mL Cyclohexane, 2.6 mL IGEPAL and 300 mu L TEOS were formed inside the carrier fluid NH4OH at a flow rate ratio of 2:1. It is observed that nanoparticles were synthesized as a result of diffusion and mixing of NH4OH inside droplets. Currently, we are working on introducing QDs in droplets and coating them with silica shells inside the microreactor. We will also study the effects of NH4OH concentration, residence time on silica shell thickness and com

URI

https://hdl.handle.net/11511/92802

DOI

https://doi.org/10.1115/icnmm2015-48765

Conference Name

13TH ASME International Conference on Nanochannels, Microchannels, and Minichannels

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Department of Metallurgical and Materials Engineering, Conference / Seminar

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SILICA NANOPARTICLE FORMATION BY USING DROPLET-BASED MICROREACTOR Nikdoost, Arsalan; Ozkan, Alican; Keleştemur, Yusuf; Demir, Hilmi Volkan; Erdem, E. Yegan (2017-01-01) This paper describes a method for the synthesis of silica nanoparticles that can be later used for coating of quantum dots inside a microfluidic reactor. Here, a droplet-based system is used where two reagents were mixed inside the droplets to obtain silica. Particles in the size range of 25 +/- 2.7 nm were obtained with comparable size distribution to controlled batch wise synthesis methods. This method is suitable to be used later to coat CdSe nanoparticles inside the microreactor.
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Citation Formats

A. Ozkan, Y. Keleştemur, H. V. Demir, and E. Y. Erdem, “SILICA SYNTHESIS & COATING OF QUANTUM DOTS IN DROPLET BASED MICROREACTORS,” presented at the 13TH ASME International Conference on Nanochannels, Microchannels, and Minichannels, San-Francisco, Kostarika, 2015, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/92802.