Molecular insight into gas separation processes in polymeric membranes

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K14644
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 19010:Fluid engineering-related
• Research Institution: The University of Tokyo
• Principal Investigator: Yoshimoto Yuta 東京大学, 大学院工学系研究科(工学部), 助教 (90772137)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Keywords: 高分子気体分離膜 / 有機・無機ハイブリッド膜 / 固有微細孔性高分子 / シリカ / 二酸化炭素 / 溶解度係数 / 拡散係数 / 分子シミュレーション

Outline of Final Research Achievements

We investigate the adsorption and diffusion behaviors of CO2, CH4, and N2 in interfacial systems composed of a polymer of intrinsic microporosity (PIM-1) and amorphous silica using molecular simulation techniques. Gas adsorption analysis indicates that gas molecules are preferentially adsorbed in microcavities distributed near silica surfaces, resulting in an increase in the solubility coefficients. Interestingly, CO2 diffusivity decreases in the presence of silica surfaces, whereas CH4 and N2 diffusivities increase. These differences are attributed to competing effects of silica surfaces: the emergence of larger pores resulting from chain packing disruption, which enhances gas diffusion, and a quadrupole-dipole interaction between gas molecules and silica surface hydroxyl groups, which retards gas diffusion. These findings add to our understanding of gas adsorption and diffusion behaviors in the vicinity of PIM-1/silica interfaces, which are unobtainable in experimental studies.

Free Research Field

計算科学

Academic Significance and Societal Importance of the Research Achievements

有機・無機ハイブリッド膜は，二酸化炭素の高透過性・高選択性を両立できる気体分離膜として，大きな注目を集めている．有機・無機ハイブリッド膜では，ポリマーと無機粒子の界面近傍における気体の溶解・拡散挙動が分離性能に大きな影響を与えるが，界面近傍の現象を実験的に詳細に捉えるのは容易ではない．本研究では，分子シミュレーションを用いることで，固有微細孔性高分子/シリカ界面における気体の溶解・拡散挙動を解明することに成功した．本研究成果は，有機/無機界面系における気体の溶解・拡散過程に関する基礎的知見を与えるものであり，種々の有機・無機ハイブリッド膜の解析に応用できるものと期待される．