Home
학과소식
세미나
기존 세미나
기존 세미나
[기계] Behavior of liquids interacting with micron-scale geometries
<KIMM-SNU 협력 자연모사 Green Technology 연구기획단 세미나>
1. 제 목 : Behavior of liquids interacting with micron-scale geometries
2. 연 사 : 최원재 박사 (Harvard University)
3. 일 시 : 2009년 12월 28일 (월요일) 오후 5시 – 6시
4. 장 소 : 서울대학교 301동 117호 (1층)
5. 초 록 :
At small scales, the effect of interfacial tensions on the behavior of fluids becomes significant. For example, it is now well-known that by controlling the surface chemistry and topographic details of a textured surface, one can manipulate liquid-air interfacial tension to implement composite superhydrophobic ‘Cassie-Baxter states’. If the surface texture becomes re-entrant (i.e. multi-valued) and very low surface energy coatings are employed, then it becomes possible to create omniphobic surfaces that repel even low tension liquids such as oils and alcohols. Repellency against low surface tension liquids, however, is at best metastable and it cannot be the global equilibrium. Multiple types of omniphobic surfaces were fabricated to investigate the underlying physics that might govern robustness, apparent contact angles, and contact angle hysteresis of noted omniphobic but metastable Cassie-Baxter states. I also investigated the possibility of a giant liquid slip over the microscopic air pockets or ‘plastron film’ trapped in the textured surfaces. I used periodic woven meshes of controlled feature size and weave, coupled with a simple elastomeric fluoropolymer dipcoating protocol, to prepare a series of model re-entrant and friction-reducing surfaces. Through this approach, it was possible to reach slip lengths as large as hundreds of microns. However, it was also revealed that the slip lengths and the robustness of a slip-inducing Cassie-Baxter regime are inversely correlated. Finally, a brief overview of my most recent research on bubble or droplet flows, confined in micro-channels, will be discussed.
6. 약 력 :
<Education>
1997, Seoul National University, B.S
1999, Seoul National University, M.S.
2009, Massachusetts Institute of Technology, Ph.D.
<Work Experience>
1999-2004, Researcher, Daewoo Electronics / MEMS division
2009-Present, Postdoc, Harvard University / Department of Chemistry
7. 문 의 : 기계항공공학부 김호영 교수 (☏ 02-880-9286)
1. 제 목 : Behavior of liquids interacting with micron-scale geometries
2. 연 사 : 최원재 박사 (Harvard University)
3. 일 시 : 2009년 12월 28일 (월요일) 오후 5시 – 6시
4. 장 소 : 서울대학교 301동 117호 (1층)
5. 초 록 :
At small scales, the effect of interfacial tensions on the behavior of fluids becomes significant. For example, it is now well-known that by controlling the surface chemistry and topographic details of a textured surface, one can manipulate liquid-air interfacial tension to implement composite superhydrophobic ‘Cassie-Baxter states’. If the surface texture becomes re-entrant (i.e. multi-valued) and very low surface energy coatings are employed, then it becomes possible to create omniphobic surfaces that repel even low tension liquids such as oils and alcohols. Repellency against low surface tension liquids, however, is at best metastable and it cannot be the global equilibrium. Multiple types of omniphobic surfaces were fabricated to investigate the underlying physics that might govern robustness, apparent contact angles, and contact angle hysteresis of noted omniphobic but metastable Cassie-Baxter states. I also investigated the possibility of a giant liquid slip over the microscopic air pockets or ‘plastron film’ trapped in the textured surfaces. I used periodic woven meshes of controlled feature size and weave, coupled with a simple elastomeric fluoropolymer dipcoating protocol, to prepare a series of model re-entrant and friction-reducing surfaces. Through this approach, it was possible to reach slip lengths as large as hundreds of microns. However, it was also revealed that the slip lengths and the robustness of a slip-inducing Cassie-Baxter regime are inversely correlated. Finally, a brief overview of my most recent research on bubble or droplet flows, confined in micro-channels, will be discussed.
6. 약 력 :
<Education>
1997, Seoul National University, B.S
1999, Seoul National University, M.S.
2009, Massachusetts Institute of Technology, Ph.D.
<Work Experience>
1999-2004, Researcher, Daewoo Electronics / MEMS division
2009-Present, Postdoc, Harvard University / Department of Chemistry
7. 문 의 : 기계항공공학부 김호영 교수 (☏ 02-880-9286)