| 研究課題/領域番号 |
19F19367
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| 研究機関 | 京都大学 |
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研究代表者 |
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| 研究分担者 |
KARAHAN HUSEYIN 京都大学, 高等研究院, 外国人特別研究員
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| 研究期間 (年度) |
2019-11-08 – 2022-03-31
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| キーワード | graphene oxide synthesis / membrane preparation |
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| 研究実績の概要 |
Our research is divided into four main tasks: (1) preparation and characterization of graphene-based nanosheets (main precursor), (2) preparation and characterization of nanosheet-based slurries (graphene-polymer mixtures), (3) fabrication of laminated membranes (via the casting of slurries on supports followed by vacuum filtration for compaction), and (4) physical characterization and performance testing of resulting membranes for gas separation.
According to our research plan, we have so far focused on Task#1. Specifically, we have achieved the following: (i) Synthesis of graphene oxide (starting by natural graphite), (ii) exfoliation of graphene oxide by high-intensity sonication, (iii) characterization of graphene oxide using spectroscopic techniques.
As planned, we have also made initial trials related to Task#2 and Task#3. Specifically, we have achieved the following: (a) preparation of graphene-based nanocomposite slurries using polyethyleneimine or poly(diallyldimethylammonium chloride), (b) preparation of laminated coatings using blade or rod coating followed by vacuum filtration.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
3: やや遅れている
理由
Our research is a little behind the initial plan for two reasons. The first reason is our limited laboratory access in the last over one month due to the coronavirus outbreak. However, we have also performed additional experimental work in consideration of the recent progress made in the field. The first reason is self-explanatory. The second reason, on the other hand, deserves further explanation.
The recent progress in the field has shown the critical role of humidity in the long-term stability of nanosheet-based laminated membranes. We originally planned to combine graphene oxide with polyethyleneimine and polyallylamine. Both of these polymers are highly water-soluble and weak cationic polyelectrolytes. To enhance the stability of the resulting complexes, we searched for an alternative system. Given polyethyleneimine is the gold standard in this line of research, we first replaced polyallylamine with a strong polyelectrolyte, poly(diallyldimethylammonium chloride). However, the preparation of consistent slurries with poly(diallyldimethylammonium chloride) turned out to be more challenging due to fast coagulation. At the same time, we have made initial trials on a water-insoluble polymer (a poly(ethylene glycol)-based block copolymer). In order not to deviate from the initially proposed plan, we have spent only 2-3 weeks on this promising system so far. However, it adds up to our slight delay in overall.
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| 今後の研究の推進方策 |
We plan to follow up on our originally proposed plan to a large extent. However, to increase the chances of generating impactful publications, we also plan to make slight modifications, as well as to conduct additional investigations. Since the original plan has been explained in our proposal in detail, these additional plans are listed below with explanations:
1) On Coating Method: As proposed in our plan, we will employ the doctor-blade coating method for film casting. However, we now also plan to compare doctor-blade coating (tape coating) with its closest relative, rod coating. By doing so, we aim to increase the novelty aspect of our research. If the rod coating method provides superior results, we might focus on rod coating instead.
2) Membrane Support: Based on the morphological assessments, our initial trials suggested that the support material used for membrane preparation is critical for achieving conformal and uniform membranes. Thus, in addition to our proposed plan, we plan to explore the role of substrates. To this end, we plan to test a variety of commercially available substrates and their chemically and thermally treated versions.
3) Membrane Carbonization: Our ultimate goal is to develop high-performance gas separation membranes using graphene-based nanosheets. One way to enhance the performance of graphene-based and polymer-based membranes is thermal treatment. If we do not achieve an appealing separation performance for desired gas pairs, we will also try to improve the separation performance via heat-induced carbonization.
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