scholarly journals Quantifying Size Exclusion by Diffusion NMR: A Versatile Method to Measure Pore Access and Pore Size

2018 ◽  
Vol 90 (19) ◽  
pp. 11431-11438 ◽  
Author(s):  
Fredrik Elwinger ◽  
Jonny Wernersson ◽  
István Furó
Keyword(s):  
Pore Size ◽  
Size Exclusion ◽  
Diffusion Nmr

scholarly journals Fractionation of Block Copolymers for Pore Size Control and Reduced Dispersity in Mesoporous Inorganic Thin Films

2020 ◽  
Author(s):  
Alberto Alvarez Fernandez ◽  
Barry Reid ◽  
Jugal Suthar ◽  
Swan Choy ◽  
Maximiliano Jesus Jara Fornerod ◽  
...  
Keyword(s):  
Thin Films ◽  
Molecular Weight ◽  
Pore Size ◽  
Protective Coatings ◽  
Size Control ◽  
Size Exclusion ◽  
Porous Network ◽  
Chromatographic Fractionation ◽  
Inorganic Thin Films ◽  
Pore Size Control

Mesoporous inorganic thin films are promising materials architectures for a variety of applications, including sensing, catalysis, protective coatings, energy generation and storage. In many cases, precise control over a bicontinuous porous network on the 10-nm length scale is crucial for their operation. A particularly promising route for structure formation utilizes block copolymer (BCP) micelles in solution as sacrificial structure-directing agents for the co-assembly of inorganic precursors. This method offers pore size control via the molecular weight of the pore forming block and is compatible with broad materials library. On the other hand, the molecular weight dependence impedes continuous pore tuning and the intrinsic polymer dispersity presents challenges to the pore size homogeneity. To this end, we demonstrate how chromatographic fractionation of BCPs provides a powerful method to control the pore size and dispersity of the resulting mesoporous thin films. We apply a semi-preparative size exclusion chromatographic fractionation to a polydisperse poly(isobutylene)-block-poly(ethylene oxide) (PIB-b-PEO) BCP obtained from scaled-up synthesis. The isolation of BCP fractions with distinct molecular weight and narrowed dispersity allowed us to not only tune the characteristic pore size from 9.1±1.5 to 14.1±2.1 nm with the identical BCP source material, but also significantly reduce the pore size dispersity compared to the non-fractionated BCP. Our findings offer a route to obtain a library of monodisperse BCPs from a polydisperse feedstock and provide important insights on the direct relationship between macromolecular characteristics and the resulting structure-directed mesopores, in particular related to dispersity.

Removal of bacteriophages with different surface charges by diverse ceramic membrane materials in pilot spiking tests

2012 ◽  
Vol 66 (1) ◽  
pp. 151-157 ◽  
Author(s):  
B. Hambsch ◽  
M. Bösl ◽  
I. Eberhagen ◽  
U. Müller
Keyword(s):  
Pore Size ◽  
Ceramic Membrane ◽  
Ceramic Membranes ◽  
Pilot Scale ◽  
Size Exclusion ◽  
Feed Water ◽  
Surface Charges ◽  
Membrane Materials ◽  
Pore Sizes ◽  
Microfiltration Membranes

This study examines mechanisms for removal of bacteriophages (MS2 and phiX174) by ceramic membranes without application of flocculants. The ceramic membranes considered included ultra- and microfiltration membranes of different materials. Phages were spiked into the feed water in pilot scale tests in a waterworks. The membranes with pore sizes of 10 nm provided a 2.5–4.0 log removal of the phages. For pore sizes of 50 nm, the log removal dropped to 0.96–1.8. The membrane with a pore size of 200 nm did not remove phages. So, the removal of both MS2- and phiX174-phages depended on the pore size of the membranes. But apart from pore size also other factors influence the removal of phages. Removal was 0.5–0.9 log higher for MS2-phages compared with phiX174-phages. Size exclusion seems to be the major but not the only mechanism which influences the efficiency of phage removal by ceramic membranes.

CO2-Responsive polymer membranes with gas-tunable pore size

2017 ◽  
Vol 53 (69) ◽  
pp. 9574-9577 ◽  
Author(s):  
Liangliang Dong ◽  
Weizheng Fan ◽  
Hongji Zhang ◽  
Mingqing Chen ◽  
Yue Zhao
Keyword(s):  
Gold Nanoparticles ◽  
Pore Size ◽  
Polymer Membranes ◽  
Polymer Membrane ◽  
Size Exclusion ◽  
Responsive Polymer

A novel type of CO2-responsive polymer membrane shows gas-tunable pore size that can be used for size exclusion-based filtration of gold nanoparticles.

Simulation of reservoir permeability decline due to invasion of large particles

2008 ◽  
Vol 48 (1) ◽  
pp. 1 ◽  
Author(s):  
Changhong Gao
Keyword(s):  
Particle Size ◽  
Porous Media ◽  
Pore Size ◽  
Test Data ◽  
Fluid Velocity ◽  
Deposition Process ◽  
Size Exclusion ◽  
Core Flooding ◽  
Gravity Settling ◽  
Permeability Damage

Particles can deposit in reservoir rocks and cause severe damage to their permeabilities. The mechanisms of permeability decline are attributed to adsorption, size exclusion and gravity settling of particles in porous media. Previous test results reveal that high particle concentration, low fluid velocity, large particle size lead to more damage. Traditional models are empirical correlations heavily dependent on core test data. In this paper, a network model incorporating the damaging mechanisms is used to study capture of large (non-Brownian) particles in porous media and resultant permeability damage. The model employs certain assumptions to imitate the characteristics of real porous media. The proposed procedure applies force analysis to obtain particle invasion depth, and determines damaging mechanisms by pore size to particle size ratio. The model assumes that for a particle much smaller than the pore where it is captured, surface deposition is the mechanism for permeability decline. For particle size comparable to pore size, pore throat plugging and bridging are the causes of permeability damage. The method is validated with test data and reasonably good results are obtained. The new model provides more insights into the deposition process and does not rely on core flooding data.

scholarly journals Electroanalysis based on stand-alone matrices and electrode-modifying films with silica sol-gel frameworks: a review

2020 ◽  
Vol 24 (11-12) ◽  
pp. 2617-2631
Author(s):  
Krzysztof Miecznikowski ◽  
James A. Cox
Keyword(s):  
Ionic Liquids ◽  
Solid State ◽  
Pore Size ◽  
Size Structure ◽  
Sol Gel ◽  
Silica Sol ◽  
Size Exclusion ◽  
Ionic Conductors ◽  
Power Sources ◽  
Analytical Applications

Abstract Silica sol-gel matrices and its organically modified analogues that contain aqueous electrolytes, ionic liquids, or other ionic conductors constitute stand-alone solid-state electrochemical cells when hosting electrodes or serve as modifying films on working electrodes in conventional cells. These materials facilitate a wide variety of analytical applications and are employed in various designs of power sources. In this review, analytical applications are the focus. Solid-state cells that serve as gas sensors, including in chromatographic detectors of gas-phase analytes, are described. Sol-gel films that modify working electrodes to perform functions such as hosting electrochemical catalysts and acting as size-exclusion moieties that protect the electrode from passivation by adsorption of macromolecules are discussed with emphasis on pore size, structure, and orientation. Silica sol-gel chemistry has been studied extensively; thus, factors that control its general properties as frameworks for solid-state cells and for thin films on the working electrode are well characterized. Here, recent advances such as the use of dendrimers and of nanoscale beads in conjunction with electrochemically assisted deposition of silica to template pore size and distribution are emphasized. Related topics include replacing aqueous solutions as the internal electrolyte with room-temperature ionic liquids, using the sol-gel as an anchor for functional groups and modifying electrodes with silica-based composites.

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