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Yoon, Suk Bon,Kim, Jong-Yun,Park, Seung-Kyu,Kim, Jung Ho,Kim, Min-Sik,Yu, Jong-Sung American Chemical Society 2011 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.50 No.13
<P>Silica-based nanocasting synthesis of a nanostructured carbon replica inevitably involves the disposal of silica waste and toxic etchant after the time-consuming and costly etching processes for selective removal of silica template from a carbon/silica composite to produce the silica-free carbon replica, not only resulting in chemical waste, but also posing serious environmental concerns. Instead of removal of the silica template, the in situ recrystallization transformation of the silica into more useful functional nanostructured silica offers an attractive alternative to the problem of handling silica waste and toxic etchants. In this work, the novel composites composed of microporous zeolite ZSM-5 crystals and hollow core-mesoporous shell carbon (HCMSC) capsules are synthesized for the first time by such transformation process of sacrificial silica template in the carbon/solid core-mesoporous shell silica (SCMSS) composite through hydrothermal process under alkaline condition. Compared to the commercial filter materials, the zeolite/HCMSC composite (BET surface area: 532–600 m<SUP>2</SUP>/g) possessing a wide range of pore sizes, i.e., micropores from zeolites, mesopores from the outer shells, and macropores from the hollow core of the carbon capsules reveals the outstanding adsorption capacity for the typical malodorous acetaldehyde. Therefore, the recrystallization approach will be appealing as a simple, economical, environmentally benign, and efficient direct synthesis process for the preparation of new multifunctional composite materials for many advanced applications such as removal of volatile organic compounds, separation, energy storage, and catalysis. Recrystallization transformation approach of sacrificial silica in silica/carbon composites is reported for the first time for the formation of new composite materials composed of microporous ZSM-5 zeolite and hollow mesoporous carbon capsules. That is, the silica template waste is utilized to produce a new highly desirable crystalline microporous ZSM-5 silica material by this approach. The composite demonstrated high adsorption capacity for acetaldehyde.</P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ie102238y'>ACS Electronic Supporting Info</A></P>
Suk Bon Yoon,Soonki Kang,유종성 한국물리학회 2006 Current Applied Physics Vol.6 No.6
Nanostructured polymer materials with interesting morphological variation, which include three dimensionally interconnecteduniform nanoporous network arrays (volume- and surface-templated ordered arrays) and hollow core spheres were synthesizedby inducing dierent polymerization process of phenol and formaldehyde as a precursor over silica templates (ordered silica colloi-dal crystals or individual silica particles). The pore sizes of the resulting nanostructured polymer materials can be easily controlledby monitoring the sizes of silica spheres, while their morphologies were modulated by controlling the initiation sites of the acid-cat-alyzed condensation reaction of the same polymer precursor and by modifying silica templates.
Yoon, Suk Bon,Kim, Jong-Yun,Kim, Jung Ho,Park, Yong Joon,Yoon, Kuk Ro,Park, Seung-Kyu,Yu, Jong-Sung Royal Society of Chemistry 2007 Journal of materials chemistry Vol.17 No.18
<P>Both particle monodispersity and mesopore orientation have been considered in this work. Monodisperse spherical silica particles with a solid core and a mesoporous shell featuring mesopore channels perpendicular to the core surface were synthesized for the first time by adopting silica particles as the core component and by employing C<SUB><I>n</I></SUB>-TAB (<I>n</I> = 12, 14, 16, 18), the structure-directing agent for the mesoporous shell. Micelles on the surface of the silica particles are formed from the electrostatic interaction between the partially negatively charged silica particles and the positively charged surfactant molecules under basic conditions. The particles synthesized in this work have a uniformly coated thin mesoporous shell of about 28–61 nm in thickness over the silica core and possess a surface area of <I>ca</I>. 370–500 m<SUP>2</SUP> g<SUP>−1</SUP>, pore volume of <I>ca</I>. 0.2–0.35 cc g<SUP>−1</SUP>, and narrow pore size distribution.</P> <P>Graphic Abstract</P><P>Monodisperse spherical silica particles with a solid core and mesoporous shell featuring mesopore channels perpendicular to the core surface were synthesized for the first time by using C<SUB><I>n</I></SUB>-TAB as a structure-directing agent for the mesoporous shell. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b617471j'> </P>
Morphological Control of Mesoporous Silica Nanoparticles and Their Application for Foam Stability
Yoon, Suk Bon,Yoon, In-Ho,Kim, Chorong,Jung, Chong-Hun,Kim, Seonbyeong,Choi, Wang-Kyu,Moon, Jei-Kwon Asian Journal of Chemistry 2014 Asian Journal of Chemistry Vol.26 No.5
<P>Mesoporous silica nanoparticles with various sizes and shapes were synthesized by varying the amount of the ammonia solution as a basic catalyst and cetyltrimethylammonium bromide (CTABr) as a cationic surfactant. It was found that the particle size and shape were strongly dependent on the amount of the ammonia solution and cetyltrimethylammonium bromide. While the mesoporous silicas exhibited the small sizes and irregular shapes when using a low concentration of the ammonia solution, the rod-like shapes with well-ordered pore structures as a MCM-41 were synthesized under a strong basic condition. Resulting materials showed high specific surface areas (813919 m(2)/g), large pore volumes (0.60-1.66 cm(3)/g) and uniform pore sizes (1.87-2.36 nm). The mesoporous silica nanoparticles with different sizes were used to investigate the effect of the nanoparticles on the foam stability. The results showed that both foam volume and liquid volume in the foam were enhanced when using a smaller size and lower density of the mesoporous silica nanopartcles.</P>
Yoon, Suk Bon,Choi, Yong Suk,Park, Yong Joon,Kim, Jong-Yun American Scientific Publishers 2008 Journal of Nanoscience and Nanotechnology Vol.8 No.10
<P>Large mesoporous silica microspheres with bimodal pore size distributions will be very promising in a special application. Silica microspheres of 10-100 microm in size were synthesized using n-dodecylamine and polymeric surfactant as co-templating agents at room temperature. Surface area and large pore volume of the mesoporous silica microspheres were 884-1009 m2/g and 1.25-1.68 cm3/g, respectively, depending on the reaction conditions. Mesoporous silica microspheres prepared using a short-chained alkylamine surfactant and a long-chained polymeric surfactant exhibited distinct bimodal pore size distribution, that is, small (< 3 nm) and large mesopores (> 20 nm). Pluronic F108, which is a poly(ethylene glycol)-poly(propylene glycol) triblock copolymer, played an important role in the formation of the large mesopores as well as the formation of stable silica microspheres without strong aggregation between particles.</P>