• Title/Summary/Keyword: Amine-coated silica particle

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Double Convective Assembly Coatings of FePt Nanoparticles to Prevent Particle Coalescence during Annealing

  • Hwang, Yeon
    • Korean Journal of Materials Research
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    • v.21 no.3
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    • pp.156-160
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    • 2011
  • FePt nanoparticles suspension was synthesized by reduction of platinum acetylacetonate and decomposition of iron pentacarbonyl in the presence of oleic acid and oleyl amine. FePt nanoparticles were coated on a substrate by convective assembly from the suspension. To prevent the coalescence during the annealing of FePt nanoparticles double convective coatings were tried. First convective coating was for silica particle assembly on a silicon substrate and second one was for FePt nanoparticles on the previously coated silica layers. It was observed by scanning electron microscopy (SEM) that FePt nanoparticles were dispersed on the silica particle surface. After annealing at $700^{\circ}C$ for 30 minutes under nitrogen atmosphere, FePt nanoparticles on silica particles were maintained in a dispersed state with slight increase of particle size. On the contrary, FePt nanoparticles that were directly coated on silicon substrate showed severe particle growth after annealing due to the close-packing of nanoparticles during assembly. The size variation during annealing was also verified by X-ray diffractometer (XRD). It was suggested that pre-coating, which offered solvent flux oppose to the capillary force between FePt nanoparticles, was an effective method to prevent coalescence of nano-sized particles under high temperature annealing.

Immobilization of the Hyperthermophilic Archaeon Thermococcus onnurineus Using Amine-coated Silica Material for H2 Production (아민기가 코팅된 규조토 담체를 이용한 초고온성 고세균 Thermococcus onnurineus의 세포 고정화 및 수소생산 연구)

  • Bae, Seung Seob;Na, Jeong Geol;Lee, Sung-Mok;Kang, Sung Gyun;Lee, Hyun Sook;Lee, Jung-Hyun;Kim, Tae Wan
    • Microbiology and Biotechnology Letters
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    • v.43 no.3
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    • pp.236-240
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    • 2015
  • Previously we reported that the hyperthermophilic archaeon, Thermococcus onnurineus NA1 is capable of producing hydrogen (H2) from formate, CO or starch. In this study, we describe the immobilization of T. onnurineus NA1 as an alternative means of H2 production. Amine-coated silica particles were effective in immobilizing T. onnurineus NA1 by electrostatic interaction, showing a maximum cell adsorption capacity of 71.7 mg-dried cells per g of particle. In three cycles of repeated-batch cultivation using sodium formate as the sole energy source, immobilized cells showed reproducible H2 production with a considerable increase in the initial production rate from 2.3 to 4.0 mmol l−1 h−1, mainly due to the increase in the immobilized cell concentration as the batch culture was repeated. Thus, the immobilized-cell system of T. onnurineus NA1 was demonstrated to be feasible for H2 production. This study is the first example of immobilized cells of hyperthermophilic archaea being used for the production of H2.

Synthesis of Polymer-Silica Hybrid Particle by Using Polyamine Nano Complex (폴리아민 나노 복합체를 이용한 고분자-실리카 복합체 입자 합성)

  • Kim, Dong-Yeong;Seo, Jun-Hee;Lee, Byungjin;Kang, Kyoung-Ku;Lee, Chang-Soo
    • Clean Technology
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    • v.27 no.2
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    • pp.115-123
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    • 2021
  • This study demonstrates a new method for the synthesis of organic-inorganic hybrid particles composed of an inorganic silica shell and organic core particles. The organic core particles are prepared with a uniform size using droplet-based microfluidic technology. In the process of preparing the organic core particles, uniform droplets are generated by independently controlling the flow rates of the dispersed phase containing photocurable resins and the continuous phase. After the generation of droplets in a microfluidic device, the droplets are photo-polymerized as particles by ultraviolet irradiation at the ends of microfluidic channels. The core particle is coated with a nano complex composed of polyallylamine hydrochloride (PAH) and phosphate ion (Pi) through strong non-covalent interactions such as hydrogen bonding and electrostatic interaction under optimized pH conditions. The polyamine nano complex rapidly induces the condensation reaction of silicic acid through the arranged amine groups of the main chain of PAH. Therefore, this method enabled the preparation of organic-inorganic hybrid particles coated with inorganic silica nanoparticles on the organic core. Finally, we demonstrated the synthesis of organic-inorganic hybrid particles in a short time under ambient and environmentally friendly conditions, and this is applicable to the production of organic-inorganic hybrid particles having various sizes and shapes.