Probing Confinement Effects on Fluid Behavior in Nanotubes
Physical Chemistry of Solids and Surfaces, Material Characterisation
Final Report Abstract
Understanding the properties of fluids and electrolytes confined in single digit nanopores, or pores with diameters < 10 nm, is at the frontier of current science and has remained limited due to challenges in experimentally accessing this extreme size regime. As part of this project, I established a carbon nanotube nanofluidic plaform that allows interrogating fluids in individual carbon nanotubes with diameters on the order of 1 nm. While carbon nanotubes provide textbook-like cylindrical confinement and can be synthesized up to millimeter lengths or more, their use as nanofluidic testbeds faces several challenges: i) they vary both in wall number and bundledness calling for careful characterization, ii) typically require an opening procedure to allow fluid filling, and iii) require a sensitive means to probe a confined fluid. I addressed these points by i) developing a platform that allows co-localized investigation of the same CNT by Raman spectroscopy and TEM, ii) introducing a CNT segmentation approach that yields multiple replicates of the same chirality CNT which serve as independent and directly comparable nanofluidic entities, and iii) further advancing the understanding of Raman radial breathing(-like) vibrational modes (RBMs)—both theoretically and experimentally—as fluid sensors and locators. These advances are covered in a series of manuscripts with a particular focus on the filling and thermodynamics of water in individual carbon nanotubes. Among the main results obtained in this project are the study of diameter-dependent shifts in RBM frequency upon water filling that to some extent may be attributed to packing effects of confined water, the quantitative assessment of the impedance to axial heat transfer from nanoconfined water, the observation of partial water filling and its isochoric thermodynamic analysis yielding a reduced (compared to the bulk) enthalpy of condensation of water, and the measurement and analysis of fluid isobars. All of these shed light on fundamental aspects of confined fluid behavior, a better understanding of which may inform the refinement of molecular force fields as well as the engineering of future technologies at the water-energy nexus. Also, as part of this project, a better understanding of quantum emitters in hexagonal boron nitride lattices could be achieved. Such emitters have shown potential for their use as quantum sensors in nanofluidics.
Publications
- Diameter dependence of water filling in lithographically segmented isolated carbon nanotubes. ACS Nano, 15, 2778-2790
S. Faucher, M. Kuehne, V. B. Koman, N. Northrup, D. Kozawa, Z. Yuan, S. X. Li, Y. Zeng, T. Ichihara, R. P. Misra, N. Aluru, D. Blankschtein and M. S. Strano
(See online at https://doi.org/10.1021/acsnano.0c08634) - Impedance of Thermal Conduction from Nanoconfined Water in Carbon Nanotube Single Digit Nanopores. J. Phys. Chem. C, 125, 25717-25728
M. Kuehne, S. Faucher, M. Liew, Z. Yuan, S. X. Li, T. Ichihara, Y. Zeng, P. Gordiichuk, V. B. Koman, D. Kozawa, A. Majumdar and M. S. Strano
(See online at https://doi.org/10.1021/acs.jpcc.1c08146)
