There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Metal–Organic Frameworks for Separations

Kenji Sumida, David L. Rogow, Jarad A. Mason, Thomas M. McDonald, Eric D. Bloch, Zoey R. Herm, Tae-Hyun Bae, Jeffrey R. Long

Carbon Dioxide Capture in Metal–Organic Frameworks

This critical review provides a processing-structure-property perspective on recent advances in cellulose nanoparticles and composites produced from them. It summarizes cellulose nanoparticles in terms of particle morphology, crystal structure, and properties. Also described are the self-assembly and rheological properties of cellulose nanoparticle suspensions. The methodology of composite processing and resulting properties are fully covered, with an emphasis on neat and high fraction cellulose composites. Additionally, advances in predictive modeling from molecular dynamic simulations of crystalline cellulose to the continuum modeling of composites made with such particles are reviewed (392 references).

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Cellulose nanomaterials review: structure, properties and nanocomposites

In recent years, numerous large-scale seawater desalination plants have been built in water-stressed countries to augment available water resources, and construction of new desalination plants is expected to increase in the near future. Despite major advancements in desalination technologies, seawater desalination is still more energy intensive compared to conventional technologies for the treatment of fresh water. There are also concerns about the potential environmental impacts of large-scale seawater desalination plants. Here, we review the possible reductions in energy demand by state-of-the-art seawater desalination technologies, the potential role of advanced materials and innovative technologies in improving performance, and the sustainability of desalination as a technological solution to global water shortages.

http://science.sciencemag.org/content/sci/333/6043/712.full.pdf

The Future of Seawater Desalination: Energy, Technology, and the Environment

The permeability of poly(dimethylsiloxane) [PDMS] to H2, O2, N2, CO2, CH4, C2H6, C3H8, CF4, C2F6, and C3F8, and solubility of these penetrants were determined as a function of pressure at 35 °C Permeability coefficients of perfluorinated penetrants (CF4, C2F6, and C3F8) are approximately an order of magnitude lower than those of their hydrocarbon analogs (CH4, C2H6, and C3H8), and the perfluorocarbon permeabilities are significantly lower than even permanent gas permeability coefficients This result is ascribed to very low perfluorocarbon solubilities in hydrocarbon-based PDMS coupled with low diffusion coefficients relative to those of their hydrocarbon analogs The perfluorocarbons are sparingly soluble in PDMS and exhibit linear sorption isotherms The Flory–Huggins interaction parameters for perfluorocarbon penetrants are substantially greater than those of their hydrocarbon analogs, indicating less favorable energetics of mixing perfluorocarbons with PDMS Based on the sorption results and conventional lattice solution theory with a coordination number of 10, the formation of a single C3F8/PDMS segment pair requires 460 J/mol more energy than the formation of a C3H8/PDMS pair A breakdown in the geometric mean approximation of the interaction energy between fluorocarbons and hydrocarbons was observed These results are consistent with the solubility behavior of hydrocarbon–fluorocarbon liquid mixtures and hydrocarbon and fluorocarbon gas solubility in hydrocarbon liquids From the permeability and sorption data, diffusion coefficients were determined as a function of penetrant concentration Perfluorocarbon diffusion coefficients are lower than those of their hydrocarbon analogs, consistent with the larger size of the fluorocarbons © 2000 John Wiley & Sons, Inc J Polym Sci B: Polym Phys 38: 415–434, 2000

Gas sorption, diffusion, and permeation in poly(dimethylsiloxane)

Polymer nanocomposites continue to receive tremendous attention for application in areas such as microelectronics, organic batteries, optics, and catalysis. We have discovered that physical dispersion of nonporous, nanoscale, fumed silica particles in glassy amorphous poly(4-methyl-2-pentyne) simultaneously and surprisingly enhances both membrane permeability and selectivity for large organic molecules over small permanent gases. These highly unusual property enhancements, in contrast to results obtained in conventional filled polymer systems, reflect fumed silica-induced disruption of polymer chain packing and an accompanying subtle increase in the size of free volume elements through which molecular transport occurs, as discerned by positron annihilation lifetime spectroscopy. Such nanoscale hybridization represents an innovative means to tune the separation properties of glassy polymeric media through systematic manipulation of molecular packing.

https://science.sciencemag.org/content/sci/296/5567/519.full.pdf

Ultrapermeable, Reverse-Selective Nanocomposite Membranes

Contributors. Preface. 1. Transport of Gases and Vapors in Glassy and Rubbery Polymers (Scott Matteucci, Yuri Yampolskii, Benny D. Freeman and Ingo Pinnau). 2. Principles of Molecular Simulation of Gas Transport in Polymers (Doros N. Theodorou). 3. Molecular Simulation of Gas and Vapor Transport in Highly Permeable Polymers (Joel R. Fried). 4. Predicting Gas Solubility in Membranes through Non-Equilibrium Thermodynamics for Glassy Polymers (Ferruccio Doghieri, Massimiliano Quinzi, David G. Rethwisch and Giulio C. Sarti). 5. The Solution-Diffusion Model: A Unified Approach to Membrane Permeation (Johannes G. (Hans) Wijmans and Richard W. Baker ). 6. Positron Annihilation Lifetime Spectroscopy and Other Methods for Free Volume Evaluation in Polymers (Yuri Yampolskii and Victor Shantarovich). 7. Prediction of Gas Permeation Parameters of Polymers (Alexander Alentiev and Yuri Yampolskii ). 8. Synthesis and Permeation Properties of Substituted Polyacetylenes for Gas Separation and Pervaporation (Toshio Masuda and Kazukiyo Nagai). 9. Gas and Vapor Transport Properties of Perfluoropolymers (Tim C. Merkel, Ingo Pinnau, Rajeev Prabhakar and Benny D. Freeman). 10. Structure and Transport Properties of Polyimides as Materials for Gas and Vapor Membrane Separation (Kazuhiro Tanaka and Ken-Ichi Okamoto). 11. The Impact of Physical Aging of Amorphous Glassy Polymers on Gas Separation Membranes (Peter H. Pfromm). 12. Zeolite Membranes for Gas and Liquid Separations (George R. Gavalas). 13. Gas and Vapor Separation Membranes Based on Carbon Membranes (Hidetoshi Kita). 14. Polymer Membranes for Separation of Organic Liquid Mixtures (Tadashi Uragami ). 15. Zeolite Membranes for Pervaporation and Vapor Permeation (Hidetoshi Kita). 16. Solid-State Facilitated Transport Membranes for Separation of Olefins/Paraffins and Oxygen/Nitrogen ( Yong Soo Kang, Jong Hak Kim, Jongok Won and Hoon Sik Kim ). 17. Review of Facilitated Transport Membranes (Richard D. Noble and Carl A. Koval ). Index.

Ingo Pinnau

Papers

Gas sorption, diffusion, and permeation in poly(dimethylsiloxane)

Ultrapermeable, Reverse-Selective Nanocomposite Membranes

Materials science of membranes for gas and vapor separation

Poly[1-(trimethylsilyl)-1-propyne] and related polymers: Synthesis, properties and functions

Polysulfone/silica nanoparticle mixed-matrix membranes for gas separation