Layer-by-layer Assembly of Nanosheets with Matching Size and Shape for More Stable Membrane Structure than Nanosheet-Polymer Assembly.

Layer-by-layer (LbL) assembly of oppositely charged materials has been widely used as an approach to make two-dimensional (2D) nanosheet-based membranes, which often involves 2D nanosheets being alternately deposited with polymer-based polyelectrolytes to obtain an electrostabilized nanosheet-polymer structure. In this study, we hypothesized that using 2D nanosheets with matching physical properties as both polyanions and polycations may result in a more ordered nanostructure with better stability than a nanosheet-polymer structure. To compare the differences between nanosheet-nanosheet vs nanosheet-polymer structures, we assembled negatively charged molybdenum disulfide nanosheets (MoS) with either positively charged graphene oxide (PrGO) nanosheets or positively charged polymer (PDDA).

Interplay of the forces governing steroid hormone micropollutant adsorption in vertically-aligned carbon nanotube membrane nanopores.

Vertically-aligned carbon nanotube (VaCNT) membranes allow water to conduct rapidly at low pressures and open up the possibility for water purification and desalination, although the ultralow viscous stress in hydrophobic and low-tortuosity nanopores prevents surface interactions with contaminants. In this experimental investigation, steroid hormone micropollutant adsorption by VaCNT membranes is quantified and explained via the interplay of the hydrodynamic drag and friction forces acting on the hormone, and the adhesive and repulsive forces between the hormone and the inner carbon nanotube wall. It is concluded that a drag force above 2.

Ion and Hydrodynamic Translucency in 1D van der Waals Heterostructured Boron-Nitride Single-Walled Carbon Nanotubes.

An unresolved challenge in nanofluidics is tuning ion selectivity and hydrodynamic transport in pores, particularly for those with diameters larger than a nanometer. In contrast to conventional strategies that focus on changing surface functionalization or confinement degree by varying the radial dimension of the pores, we explore a unique approach for manipulating ion selectivity and hydrodynamic flow enhancement by externally coating single-walled carbon nanotubes (SWCNTs) with a few layers of hexagonal boron nitride (h-BN). For van der Waals heterostructured BN-SWCNTs, we observed a 9-fold increase in cation selectivity for K versus Cl compared to pristine SWCNTs of the same 2.

Fast Water Transport through Subnanometer Diameter Vertically Aligned Carbon Nanotube Membranes.

Small-diameter carbon nanotubes (CNTs) have outstanding mass-transport properties, especially enhanced water flow. Here, we report on water transport through the first macroscopic membranes with vertically oriented, subnanometer (0.8 nm) CNT pores, made by a scalable, solution-based method with electric-field alignment of bulk-grown single-wall CNTs (SWCNTs).

Modifying the Molecular Structure of Carbon Nanotubes through Gas-Phase Reactants.

Current approaches to carbon nanotube (CNT) synthesis are limited in their ability to control the placement of atoms on the surface of nanotubes. Some of this limitation stems from a lack of understanding of the chemical bond-building mechanisms at play in CNT growth. Here, we provide experimental evidence that supports an alkyne polymerization pathway in which short-chained alkynes directly incorporate into the CNT lattice during growth, partially retaining their side groups and influencing CNT morphology.