Simulation and analysis of slip flow of water at hydrophobic silica surfaces of nanometer slit pores
- Univ. of Utah, Salt Lake City, UT (United States)
Water flow in nanopores is controlled fundamentally by pore wettability and interfacial water features. In the research herein reported, Molecular dynamics (MD) was used to simulate water flow in nanometer slit pores of silica surfaces with variable wetting characteristics. Compared to Couette flow, the simulated slit-pores of the talc (001) and octadecyltrichlorosilane (OTS) monolayer surfaces exhibited water flow enhancement and a positive slip length at the interface, whereas water flow velocity at the quartz (001) and amorphous silica surfaces was zero, adhering to the no slip condition. More intensive interactions between the interfacial water and hydrophilic silica surfaces were confirmed by MD simulation and sum-frequency vibrational spectroscopy (SFVS) results. A water exclusion zone of approximately 3 Å was found at the hydrophobic silica surfaces by quantitative MD interfacial water analysis and validated by SFVS. This exclusion zone dimension was similar in magnitude to the slip length (4–5 Å) as determined from simulated water flow in hydrophobic silica slit pores. The simulated slip lengths at the hydrophobic surfaces (0.2–1 nm) were significantly less than the experimental slip lengths (>40 nm) reported in the literature. In the case of the experimental results, this difference appears to be due to nanobubbles expected to be present at hydrophobic surfaces.
- Research Organization:
- Univ. of Utah, Salt Lake City, UT (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- SC0019285
- OSTI ID:
- 1866126
- Journal Information:
- Colloids and Surfaces. A, Physicochemical and Engineering Aspects, Vol. 626; ISSN 0927-7757
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Silica Surface States and their Wetting Characteristics
Molecular dynamics simulations study of nano bubble attachment at hydrophobic surfaces