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Abstract The presence of a solvent in a dense polymeric nanofiltration membrane layer can affect the macromolecular dynamics of the polymer material and the mobility of the solvent penetrant molecules. In addition, even the affinity of the swollen material for the solvent molecules can be distinct from that of the pure polymer material. These effects can substantially affect the membrane's performance. This paper provides sorption and swelling data of 9 thin polymer films that are commonly used for organic solvent nanofiltration (P84, Matrimid, PEI, PAN, PES, PSf, PEBAX, PTMSP, PDMS) swollen by 10 common solvents (hexane, toluene, dichloromethane, ethyl acetate, methyl ethyl ketone, acetone, isopropanol, ethanol, methanol, water). The paper describes the swelling dynamics during short-term solvent exposure (0–8 h), assesses the stability upon long-term solvent exposure (up to 2 months), and provides quantitative data on the solvent volume fractions inside the swollen layers. Among the surprising findings are the glubbery behavior of PTMSP and the completely different response of PES and PSf to toluene exposure. The results of this work demonstrate three crucial findings relevant to organic solvent nanofiltration membranes and other applications: 1. For many polymers, the swelling changes over long timescales of up to 2 months and longer. Results obtained on short timescales do however not always allow for direct extrapolation to longer time scales. 2. Structural similarity of polymers does not guarantee similar swelling behavior. 3. Swelling behavior of solvents cannot be solely explained by classifying solvents into aprotic, polar aprotic and polar protic solvents. The results of this work can aid in constructing transport models and can help predicting polymer-solvent compatibility and membrane performance in OSN applications. Graphical abstract fx1 Highlights • Many polymers do not reach equilibrium swelling after 2 months, not even for thin films. • Structural similarity of polymers does not guarantee similar swelling behavior. • Swelling behavior cannot be solely explained by classifying solvents into aprotic, polar aprotic and polar protic solvents. • PTMSP behaves like a 'glubber'. [ABSTRACT FROM AUTHOR]

The accuracy of spectroscopic ellipsometry studies of transparent polymer films in the visible wavelength range is greatly reduced in the presence of a liquid ambient. The relatively high refractive index of a liquid ambient strongly amplifies the effects of experimental non-idealities, such as window birefringence and an unknowingly inaccurate description of the optical properties of the ambient. In particular for thin films (approximately <100 nm), the implications of even small non-idealities are substantial, and large deviations in the thickness and refractive index are found. The concurrent low root mean square error (MSE) values show that a good MSE does not show that the optical model is correct; it just shows a good agreement between the experimental and fitted data. This implies that quantitative in situ ellipsometry studies for thin films are intricate, and derived properties like sorption behaviour should be treated with caution. Here, we show that quantitative in situ ellipsometry swelling measurements in solvents require a very accurate solvent dispersion relation, a high-quality temperature control, especially to prevent temperature differences between the cell, its content and exterior ambient, and accurate quantification of window effects, in particular for polymer films with thicknesses of approximately below 100 nm, depending on the optical contrast of the polymer-solvent system. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Hybrid organosilica molecular sieving membranes with ethylene bridges are generally consolidated at 250–300 °C for 2–3 hours, after which the material structure is assumed to be stabilized. This study shows that the consolidation process still continues at these temperatures after days to weeks. Ongoing condensation and structural evolution are studied in powders, films and gas permeation membranes derived from 1,2-bis(triethoxysilyl)ethane (BTESE) that are kept at temperatures up to 300 °C for days and analyzed with in situ Fourier-transform infrared spectroscopy, 29Si cross-polarized magic angle spinning nuclear magnetic resonance, in situ spectroscopic ellipsometry, in situ gas permeation and in situ X-ray reflectivity. A continuously ongoing decrease in both silanol concentration and film thickness is observed, accompanied by changes in density, thermal expansion and micropore structure. The changes in the micropore structure are found to depend on pore size and affect the gas permeation performance of membranes. An important factor in the structural evolution is the network flexibility. Materials containing no organic bridges, short flexible bridges or long rigid bridges (derived from tetraethoxysilane (TEOS), bis(triethoxysilyl)methane (BTESM) and 1,4-bis(triethoxysilyl)benzene (BTESB), respectively) also show ongoing condensation, but their shrinkage rate is smaller as compared to BTESE-derived networks. A BTESE-derived film kept at 236 °C for 12 days still shows no signs of approaching a structurally stabilized state. [ABSTRACT FROM AUTHOR]

Thin film and bulk, sulfonated poly(ether ether ketone) (SPEEK) have been subjected to a thermal treatment at 160-250 °C for up to 15 h. Exposing the films to 160 °C already causes partial desulfonation, and heating to temperatures exceeding 200 °C results in increased conjugation in the material, most likely via a slight cross-linking by H-substitution. It is well-known that the sulfonate proton plays a major role in the desulfonation reactions, and exchanging the protons with other cations can inhibit both protodesulfonation as well as electrophilic cross-linking reactions of the sulfonate group with other chains. Yet, the implications of such ion-exchange for the thermal processing of sulfonated polymer films has not been recognized. Our study demonstrates that the ion exchange stabilizes thin films and bulk SPEEK up to temperatures exceeding 200 °C, opening up ways for the thermal processing of SPEEK in the temperature range of 160-220 °C without adverse effects. [ABSTRACT FROM AUTHOR]

Precise and accurate temperature control is pertinent to studying thermally activated processes in thin films. Here, we present a calibration method for the substrate–film interface temperature using spectroscopic ellipsometry. The method is adapted from temperature calibration methods that are well developed for thermogravimetric analysis and differential scanning calorimetry instruments, and is based on probing a transition temperature. Indium, lead, and zinc could be spread on a substrate, and the phase transition of these metals could be detected by a change in the Ψ signal of the ellipsometer. For water, the phase transition could be detected by a loss of signal intensity as a result of light scattering by the ice crystals. The combined approach allowed for construction of a linear calibration curve with an accuracy of 1.3 °C or lower over the full temperature range. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) membranes have shown large potential for applications in water treatment. Being able to make these membranes in a hollow fiber geometry allows for higher surface-to-volume ratios. In this study, we present a thermal treatment procedure that is tuned to produce porous silicon carbide hollow fiber membranes with sufficient mechanical strength. Thermal treatments up to 1500 °C in either nitrogen or argon resulted in relatively strong fibers, that were still contaminated with residual carbon from the polymer binder. After treatment at a higher temperature of 1790 °C, the mechanical strength had decreased as a result of carbon removal, but after treatments at even higher temperature of 2075 °C the SiC-particles sinter together, resulting in fibers with mechanical strengths of 30–40 MPa and exceptionally high water permeabilities of 50,000 L m −2 h −1 bar −1 . Combined with the unique chemical and thermal resistance of silicon carbide, these properties make the fibers suitable microfiltration membranes or as a membrane support for application under demanding conditions. [ABSTRACT FROM AUTHOR]

A route for the fabrication of porous inorganic hollow fibers with high surface-area-to-volume ratio that avoids harmful solvents is presented. The approach is based on bio-ionic gelation of an aqueous mixture of inorganic particles and sodium alginate during wet spinning. In a subsequent thermal treatment, the bio-organic material is removed and the inorganic particles are sintered. The method is applicable to the fabrication of various inorganic fibers, including metals and ceramics. The route completely avoids the use of organic solvents, such as N-methyl-2-pyrrolidone, and additives associated with the currently used fiber fabrication methods. In addition, it inherently avoids the manifestation of so-called macro voids and allows the facile incorporation of additional metal oxides in the inorganic hollow fibers. [ABSTRACT FROM AUTHOR]

Theincorporation of an organic group into sol–gel-derivedsilica causes significant changes in the structure and propertiesof these materials. Therefore, the thermal treatment of organosilicamaterials may require a different approach. In the present paper,kinetic parameters (activation energy, pre-exponential constant, andreaction models) have been determined from mass loss data for thedehydration, dehydroxylation, and decomposition reactions that takeplace upon heating silica and organosilica. Parameters were obtainedby employing model-free isoconversional methods to data obtained undermultiple heating rates as well as by multivariate analysis of thekinetics using a multistep reaction model with distributed activationenergy. For silica, it can be concluded that the reaction atmosphere(i.e., inert or thermo-oxidative) has no influence on the reactionrate of the dehydration and dehydroxylation reactions that are responsiblefor the densification of the material. Under inert atmosphere, fulldehydration can be reached without affecting the organic moiety. Achievingcomplete dehydroxylation of the organosilica is practically impossibleas decomposition does manifest itself under commonly employed calcinationtemperatures. This indicates that prudence is required in designinga heat treatment program for these hybrid materials. To aid in optimizingthe thermal treatment, a predictive model was developed, which canbe used to forecast the extent of dehydration, dehydroxylation, anddecomposition reactions under a multitude of temperature programs. [ABSTRACT FROM AUTHOR]

Front Cover: The cover illustrates proton (H)‐ and sodium (Na)‐ form of sulfonated poly(ether ether ketone) membrane films. In the image, the film H‐membrane undergoes degradation and cross‐linking upon heating to 190 °C, resulting in a red color of the material, while the Namembrane remains unchanged. The significantly enhanced thermal stability of Na‐membranes allows for processing at elevated temperatures without adverse effects. Further details can be found in the article by B. T. Koziara, E. J. Kappert, W. Ogieglo, K. Nijmeijer, M. A. Hempenius and N. E. Benes on page 71. [ABSTRACT FROM AUTHOR]

The front cover page of the journal "ChemSusChem" is presented.