• Title/Summary/Keyword: hollow particle

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Synthesis of Hollow Silica Using PMMA Particle as a Template (PMMA 고분자 입자를 템플릿으로 이용한 실리카 중공체의 제조)

  • Hwang, Ha-Soo;Cho, Kye-Min;Park, In
    • Applied Chemistry for Engineering
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    • v.21 no.3
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    • pp.353-355
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    • 2010
  • Poly(methyl methacrylate) (PMMA) particles were prepared by soap-free emulsion polymerization of MMA in the presence of a cationic initiator, 2,2'-azobis(2-methylpropionamidine) (AIBA). The Stober method has been adopted to coat silica on the surface of these cationic particles. Negatively charged silica precursors were coated onto cationic particle surfaces by electronic interaction. During the coating process, hollow particles were directly obtained by dissolution of PMMA.

Preparation of polymer composites containing hollow magnetic particles and measurement of their electromagnetic properties (중공 자성입자를 포함한 복합재료 제조 및 전자파 특성 측정)

  • Yi, Jin-Woo;Lee, Sang-Bok;Kim, Jin-Bong;Lee, Sang-Kwan;Park, Ki-Yeon
    • Composites Research
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    • v.21 no.2
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    • pp.31-35
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    • 2008
  • In order to design light weight and high efficient electromagnetic wave absorbing materials, hollow magnetic particles have been introduced in this study. The electroless plating method has been utilized to coat Ni and Fe on the substrates of synthesized polystyrene particles of submicron size. Removing polystyrene particles by heat treatment resulted in hollow structures. Observation by SEM, TEM and EDS confirmed the surface morphology and coating thickness of Ni and Fe. Polymeric composites containing hollow particles were tested in order to compare the electromagnetic properties between Ni coated and Fe costed particles. The composite of 30 wt% Fe hollow particles showed the higher complex permeability than Ni hollow particles or the conventional barium ferrite particles.

Morphological Study on PNIPAAm Hydrogel Microspheres Prepared by Using SPG Membrane Emulsification and UV Photopolymerization (SPG 막유화 및 UV 광중합법에 의해 제조된 PNIPAAm 하이드로젤 입자의 형태학에 관한 연구)

  • Lee, Yun Jig;Kim, Mi Ri;Cheong, In Woo
    • Journal of Adhesion and Interface
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    • v.16 no.2
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    • pp.76-82
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    • 2015
  • W/O emulsions were prepared from the aqueous solution containing NIPAAm, MBA, and APS in the continuous phase of toluene and mineral oil mixture with HMP and Span80 by using SPG membrane emulsification, and followed by the formation of PNIPAAm hydrogel microspheres through UV photopolymerization. As the ratio of mineral oil to toluene increased in the continuous phase, both particle size of the hydrogel increased and density of PNIPAAm polymer in the hydrogel particle increased, and which significantly affected swelling/deswelling ratio ($V/V_o$) with temperature change around VPTT. When the polymerization temperature was below LCST ($20^{\circ}C$), PNIPAAm hydrogel showed filled particle morphology; however, it was turned out to hollow particle morphology with thick shell layer with $40^{\circ}C$. Both density of PNIPAAm and gel content of the hydrogel increased with the increase in MBA concentration.

Fabrication of Hollow Micro-particles with Nonspherical Shapes by Surface Sol-gel Reaction (표면 솔-젤 반응을 활용한 마이크로미터 크기의 비구형상 공동 입자의 제조)

  • Cho, Young-Sang;Jeon, Seog-Jin;Yi, Gi-Ra
    • Korean Chemical Engineering Research
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    • v.45 no.6
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    • pp.611-618
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    • 2007
  • We demonstrate the sol-gel coating technique of colloidal clusters for producing hollow micro-particles with complex morphologies. Cross-linked amidine polystyrene (PS) microspheres were synthesized by emulsifier-free emulsion copolymerization of styrene and divinylbenzene. The amidine PS particles were self-organized inside toluene-in-water emulsion droplets to produce large quantities of colloidally stable clusters. These clusters were coated with thin silica shell by sol-gel reaction of tetraethylorthosilicate (TEOS) and ammonia, and the organic polystyrene cores were removed by calcination at high temperature to generate nonspherical hollow micro-particles with complex morphologies. This process can be used to prepare hollow particles with shapes such as doublets, tetrahedra, icosahedra, and others.