Snap-through in Graphene Nanochannels: With Application to Fluidic Control

Abstract

Recent studies on the structure and transport behaviors of water confined within lamellar graphene have attracted intense interest in filtration technology, but the mechanism of water transport in complex membrane nanostructures remains an open question. For example, similar systems but at much larger scales have indicated that the instabilities of an elastic structure, such as snap-through, play an essential role in controlling the fluid flow. Graphene sheets, which have an atomic thickness, often appear highly wrinkled in nanofluidic devices and so are vulnerable to elastic instabilities. However, it remains unclear how does the flexible wrinkled structure affect the transport of water and filtration efficiency or whether such an effect can be exploited in devices. In this work, we explore the flow-induced snap-through in graphene nanochannels by combining molecular simulations with the theoretical analysis. We further demonstrate its applications to passive control of fluid flow and to ion/molecule selection. By introducing a flexible arch embedded within a graphene nanochannel, we observe the “snap” of the arched graphene wall from one stable state to another by varying the fluid flux (i.e., velocity); the critical velocity of this snap transition is found to depend nonmonotonically on the geometric size of the channel and the arch. We also demonstrate reversible snap-through by fixing the end parts of the flexible arch. These results suggest the potential of flow-induced snap-through in graphene-based nanochannels for ion/molecule selection applications in, for example, the design of a foul-resistant, easy-to-clean, reusable filter membrane.

Continuous Water Filling in a Graphene Nanochannel: A Molecular Dynamics Study

“…Nanoconfined water is ubiquitous in a wide variety of fields from biology and chemistry to the chemical industry with significant attentions. − The advances in fabrication of low dimension materials, such as carbon nanotubes (CNT), , boron nitride nanotubes (BNNT), graphene, graphene oxide (GO), molybdenum disulfide (MoS 2 ), and hexagonal boron nitride ( h BN), offers the opportunity to investigate the properties of confined molecules/ions down to the nanometer or even angstrom scale. ,− , The physiochemical properties of nanoconfined water or other molecules are quite different from the bulk phase that showing charming performances. ,,− Highly efficient transport of water , and precise ion separation − through nanomaterial-based membrane have been reported recently, which hold high promise in the application of water desalination, ions/molecules separation, − energy conversion, , and so on. These unique and interesting properties are closely related to the distinct nanoconfined molecule/ion structures and interfacial property.…”

Confinement-Controlled Aqueous Chemistry within Nanometric Slit Pores

“…The dynamics of water in slit pores keeps being investigated, in particular the way in which it may be affected by the asymmetry of the confining surfaces, meaning hydrophilic and hydrophobic surfaces at each side of the water lamella, and also how it can be controlled or enhanced by the application of light pulses . Other computational studies are aimed at ion solvation, ion separation, and transport properties of slit pores , and their possible control by the use of flexible confining surfaces or by their functionalization . Finally, we note that most simulations are still done with force fields, in particular employing water models that have been optimized to describe bulk properties rather than water in narrow slit pores including its peculiar wall interactions.…”

Atomistic Simulations of the Permeability and Dynamic Transportation Characteristics of Diamond Nanochannels

“…The interlayer distance, or the channel height, determines the degree of confinement on the solution, and a wide range of factors affect the transportation behavior of the confined solutions, such as atomic structure, surface curvature, surface charge [ 18 ], chirality [ 47 ], pressure [ 48 ], and in-plane strain [ 49 ]. Due to its low bending stiffness, graphene is often presented with strong wrinkles, which could introduce strong impact on the solution behavior in nanofluidic devices [ 50 ]. Recently, researchers successfully prepared ultrathin 2D diamond [ 51 , 52 , 53 ], which provides a new candidate to construct 2D nanochannels.…”