2017 Fiscal Year Annual Research Report
mpact of size asymmetry between the constituents of a mixture on the kinetic pathway of phase separation
| Project/Area Number |
17F17704
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| Research Institution | The University of Tokyo |
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Principal Investigator |
田中 肇 東京大学, 生産技術研究所, 教授 (60159019)
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| Co-Investigator(Kenkyū-buntansha) |
ABUILLAN WASIM 東京大学, 生産技術研究所, 外国人特別研究員
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| Project Period (FY) |
2017-04-26 – 2019-03-31
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| Keywords | コロイド / 粘弾性相分離 |
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| Outline of Annual Research Achievements |
The primary goal of the project is to investigate the behavior of asymmetric colloidal system. To reach this goal, first I learned the synthesis of colloidal PMMA particles and successfully could produce fluorescently labeled micro sized particles with low polydispersity. In order to define the electrostatic nature of the studied system, first, I systemically improved an electrophoresis measurement procedure to determine the charge of the colloidal particles. Second, I constructed a self-made conductivity meter to probe the free ion concentration in organic solvents. Eventually, a size asymmetric colloidal system with well-defined physical properties was achieved. The system consists of two colored particles with 2.3 μm and 3.1 μm in size immersed in density and refractive index matched solvent (cis-decalin, CHB). Colloidal systems were prepared by varying the number ratio between 2.3 and 3.1 sized particles and observed using laser confocal microscopy. The results were analyzed in terms of the structure factor. Further fine adjustment of the experimental procedure is required to reach high quality results.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
As explained previously, the system of interest is made of colloids with two different particles sizes suspended in a solvent. Since the particles were synthesized in different patches, their density is slightly different causing a phase separation of the two component due to gravity. To avoid this problem an in going improvement in the preparation procedure is under investigation. To probe the dynamics of colloidal systems undergoing gel transition, an advanced experiment (X-ray photon correlation spectroscopy) at ESRF in France were carried out with collaborations with the group of Prof. Motomu Tanaka in Heidelberg University, Germany. The primary experiment targeted the gelation dynamics of nano-colloidal particles in polymer suspension at the interface between oil and water, which is the first experiment of its kind and very technically challenging which currently under improvement. However, our primary results enabled us to get an X-ray beam time to study the structure of two-dimensional colloidal systems under various electrostatic conditions. The system consists of proteins nano-particles adsorbed onto electrostatically charged surfaces. The X-ray beam time is scheduled in May 7th-11th and preparation is on- going between international team members from interdisciplinary fields.
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| Strategy for Future Research Activity |
In the next two months mainly in May and June a special focus will put into performing and afterwards analyzing the data from the X-ray reflectivity and grazing incidence small angle X-ray scattering experiments which is scheduled in May 7th-11th. The amount of data is expected to be hug and probably the analysis might be extended another 1-2 months depending on the success rate of the beam time. Depending on the outcome, a beam time at ESRF in June 20th-26th dedicated to probe ions concentration profiles is under consideration to quantify the impact of electrostatics on colloidal structures as a collaboration with prof. Ali Makky, CNRS-Paris, France. From July to October 2018, intensive experiments using laser confocal microscopy on binary colloidal system will be in focus and in parallel writing manuscript based on scattering results. From November 2018 to January 2019 analysis of the microscopy results. Finally, the last three months in the fellowship period will be dedicated in wrapping up the ultimate results into a second publishable paper.
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