Electrically controlled mass transport into microfluidic droplets from nanodroplet carriers with application in controlled nanoparticle flow synthesis
| Autor: | Cao Zheng, Yunfei Zhang, Saif A. Khan, T. Alan Hatton, Tonghan Gu, Fan He |
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| Přispěvatelé: | Massachusetts Institute of Technology. Department of Chemical Engineering, Massachusetts Institute of Technology. Department of Chemistry, Gu, Tonghan, Zheng, Cao, He, Fan, Zhang, Yunfei, Khan, Saif A, Hatton, Trevor Alan |
| Rok vydání: | 2018 |
| Předmět: |
Materials science
Microfluidics Biomedical Engineering Metal Nanoparticles Nanoparticle Bioengineering Nanotechnology 02 engineering and technology 010402 general chemistry 01 natural sciences Biochemistry chemistry.chemical_compound Electricity Particle Size General Chemistry Square wave Models Theoretical 021001 nanoscience & nanotechnology 0104 chemical sciences Miniemulsion Chemical species chemistry Colloidal gold Chloroauric acid Emulsions Gold Particle size 0210 nano-technology |
| Zdroj: | Royal Society of Chemistry |
| ISSN: | 1473-0189 1473-0197 |
| Popis: | Microfluidic droplets have been applied extensively as reaction vessels in a wide variety of chemical and biological applications. Typically, once the droplets are formed in a flow channel, it is a challenge to add new chemicals to the droplets for subsequent reactions in applications involving multiple processing steps. Here, we present a novel and versatile method that employs a high strength alternating electrical field to tunably transfer chemicals into microfluidic droplets using nanodroplets as chemical carriers. We show that the use of both continuous and cyclic burst square wave signals enables extremely sensitive control over the total amount of chemical added and, equally importantly, the rate of addition of the chemical from the nanodroplet carriers to the microfluidic droplets. An a priori theoretical model was developed to model the mass transport process under the convection-controlled scenario and compared with experimental results. We demonstrate an application of this method in the controlled preparation of gold nanoparticles by reducing chloroauric acid pre-loaded in microfluidic droplets with l-ascorbic acid supplied from miniemulsion nanodroplets. Under different field strengths, l-ascorbic acid is supplied in controllable quantities and addition rates, rendering the particle size and size distribution tunable. Finally, this method also enables multistep synthesis by the stepwise supply of miniemulsions containing different chemical species. We highlight this with a first report of a three-step Au-Pd core-shell nanoparticle synthesis under continuous flow conditions. |
| Databáze: | OpenAIRE |
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