Porous+materials
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Processable High Internal Phase Pickering Emulsion Using Depletion Attraction
Professor Siyoung Choi’s research team from the KAIST Department of Chemical & Biomolecular Engineering used physical force to successfully produce a stable emulsion.
Emulsions, commonly known as cosmetic products, refer to stably dispersed structures of oil droplets in water (or water droplets in oil). Pickering emulsions refer to emulsions stabilized using solid particles, instead of detergent. Traditionally, it is said that water and oil do not mix. Until recently, detergent was added to mix oil and water for dispersion. Emulsions have traditionally been produced using this technique and are currently used for products such as mayonnaise, sun block, and lotion.
On the other hand, Pickering emulsions have been used after stabilization of chemical treatments on solid particle surfaces to enhance adsorption power. However, there were limitations in its application, since the treatment process is complex and its applicable range remains limited. Instead of chemical treatment on Pickering emulsion surfaces, the research team mixed small macromolecules a few nanometer in size with larger solid particles (tens of nanometers to a few micrometers). This induced depletion force was used to successfully stabilize the emulsion.
Depletion force refers to the force a large number of small particles induces to aggregate the bigger particles, in order to secure free space for themselves. In short, the force induces an attraction between larger particles. Until now, depletion force could only be applied to solids and solid particles. However, the research team used macromolecules and large particles such as solid particles and oil droplets to show the applicability of depletion force between solids and liquids. By introducing macromolecules that act as smaller particles, hydrophilic solid particles enhanced the adsorption of solid particles to the oil droplet surface, while preventing dissociation from the particle surface, resulting in the maintenance of a stable state.
The research team confirmed the possibility of the simple production of various porous macromolecular materials using stable Pickering emulsions. Such porous macromolecules are expected to be applicable in separation film, systems engineering, drug delivery, and sensors, given their large surface area.
Professor KyuHan Kim, the first author said, “Until now, depletion force has only been used between solid colloid particles. This research has scientific significance since it is the first example of using depletion force between solid particles and liquid droplets.”
Professor Choi said, “Beyond its academic significance, this technology could contribute to industries and national competitiveness.” He continued, “Since this technology uses physical force, not chemical, to produce stable emulsion, it can be used regardless of the type of solid particle and macromolecule. Further, it could be used in customized porous material production for special purposes.”
The research was published in Nature Communications online on February 1. In particular, this research is significant since an undergraduate student, Subeen Kim, participated in the project as a second author through the KAIST Undergraduate Research Program (URP). This research was funded by the National Research Foundation of Korea.
(Figure 1: Images of the inner structure of porous macromolecules produced using the new technology)
(Figure 2: Images showing the measurement of rheological properties of Pickering emulsions and system processability)
(Figure 3: Images showing a stable Pickering emulsion system)
2017.04.19 View 8224 -
Thomson Reuters Nominates Distinguished Professor Ryong Ryoo for Its 2014 Nobel Citation Laureates in Chemistry
The Intellectual Property & Science business of Thomson Reuters announced on September 25th its “2014 Citation Laureates,” a list of candidates considered likely to win the Nobel Prize in the fields of physics, chemistry, physiology or medicine, and economics. The annual Thomson Reuters Citation Laureates will be recognized in perpetuity as contenders for a Nobel Prize.
Distinguished Professor Ryong Ryoo of the Department of Chemistry, KAIST, has been nominated for the 2014 Thomson Reuters Citation Laureates in Chemistry. He is the first Korean scientist who has made the list. In addition to Professor Ryoo, seven other scientists were selected as possible contenders for the 2014 Nobel Prize in Chemistry, or in the future.
Professor Ryoo was named alongside Charles T. Kresge, Chief Technology Officer of Saudi Aramco, Dhahran, and Galen D. Stucky, Professor of the Department Chemistry and Biochemistry at the University of California, Santa Barbara, for their research on the design of functional mesoporous materials (http://sciencewatch.com/nobel/2014-predictions/chemistry-laureates). Mesoporous materials have high surface areas with narrow pore-sized distribution and tunable pores diameters, offering promising properties and applications in various areas including adsorption, separation, sensing, and catalysis.
Professor Ryoo has focused his research interest in the synthesis of new functional nanoporous materials such as hierarchical zeolites, mesoporous silicas, carbons, and organic-inorganic composite materials that can be used for advanced applications in the production of alternative energy sources and in green chemical processes.
According to the press release by the Thomson Reuters, the list of the 2014 Nobel predictions includes 27 researchers representing 27 distinct academic and research organizations across nine different countries.
The annual Thomson Reuters Citation Laureates study is based on the analysis of proprietary data from the research and citation database, identifying the most influential researchers in the categories of chemistry, physics, physiology or medicine, and economics. Since its inception in 2002, the study has accurately forecasted 35 Nobel Prize winners. For the full text of the press release, please go to: http://thomsonreuters.com/press-releases/092014/2014-nobel-laureates-predictions.
2014.09.29 View 11242