title: Single-walled aluminosilicate nanotube/poly(vinyl alcohol) nanocomposite membranes.
abstract: The fabrication, detailed characterization, and molecular transport properties of nanocomposite membranes containing high fractions (up to 40 vol %) of individually-dispersed aluminosilicate single-walled nanotubes (SWNTs) in poly(vinyl alcohol) (PVA), are reported. The microstructure, SWNT dispersion, SWNT dimensions, and intertubular distances within the composite membranes are characterized by scanning and transmission electron microscopy (SEM and TEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), XRD rocking curve analysis, small-angle X-ray scattering (SAXS), and solid-state NMR. PVA/SWNT nanocomposite membranes prepared from SWNT gels allow uniform dispersion of individual SWNTs in the PVA matrix with a random distribution of orientations. SAXS analysis reveals the length (∼500 nm) and outer diameter (~2.2 nm) of the dispersed SWNTs. Electron microscopy indicates good adhesion between the SWNTs and the PVA matrix without the occurrence of defects such as voids and pinholes. The transport properties of the PVA/SWNT membranes are investigated experimentally by ethanol/water mixture pervaporation measurements, computationally by grand canonical Monte Carlo and molecular dynamics, and by a macroscopic transport model for anisotropic permeation through nanotube-polymer composite membranes. The nanocomposite membranes substantially enhance the water throughput with increasing SWNT volume fraction, which leads to a moderate reduction of the water/ethanol selectivity. The model is parameterized purely from molecular simulation data with no fitted parameters, and shows reasonably good agreement with the experimental water permeability data.
authors.affiliation: School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
authors.forename: Dun-Yen
authors.initials: DY
authors.lastname: Kang
authors.forename: Ho Ming
authors.initials: HM
authors.lastname: Tong
authors.forename: Ji
authors.initials: J
authors.lastname: Zang
authors.forename: Rudra Prosad
authors.initials: RP
authors.lastname: Choudhury
authors.forename: David S
authors.initials: DS
authors.lastname: Sholl
authors.forename: Haskell W
authors.initials: HW
authors.lastname: Beckham
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Jones
authors.forename: Sankar
authors.initials: S
authors.lastname: Nair
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D008567:Membranes, Artificial; D053761:Nanocomposites / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry*; D011142:Polyvinyl Alcohol / Q000737:chemistry*
chemical_list: D000538:Aluminum Silicates; D008567:Membranes, Artificial; C049037:aluminosilicate; D011142:Polyvinyl Alcohol