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Surface crosslinking of a poly[1-(trimethylsilyl)-1-propyne] (PTMSP) film via thiol-ene click reactions with dithiothreitol produces membranes having CO2/N2 selectivities in excess of 30 with CO2 permeances in excess of 300 GPU.

Defects within single, double, and triple polyelectrolyte bilayers derived from poly(sodium 4-styrenesulfonate) (PSS) and poly(diallyldimethyammonium chloride) (PDDA) have been repaired using aqueous solutions of sodium dodecyl sulfate (SDS), as evidenced by a reduction in their permeability and an increase in their permeation selectivity. In contrast to the use of monomer solutions of SDS, which were moderately effective in repairing only double and triple bilayers, micellar solutions proved highly effective for all three assemblies. Evidence for intact micelles or micellar fragments being deposited on the surface of single bilayers of PSS/PDDA has been obtained from a combination of atomic force microscopy, X-ray photoelectron spectroscopy, ellipsometry, and contact angle measurements. Observed CO

The surface crosslinking of poly[1-(trimethylsilyl)-1-propyne] (PTMSP) membranes by dithiothreitol under thiol-ene click reaction conditions has yielded membranes having CO

Electroactive coatings based on non-conjugated redox-active polymers have increased in popularity with the development of thin film organic batteries. Control over coating deposition, redox-activity, and ion transport are key to improving their energy storage performance. In this work, the synthesis, solution state electrochemical characterization, and layer-by-layer (LbL) assembly of a nitroxide-based polycation and polyanion are presented. Solution state electrochemical characterization indicates that the rate of electron transfer for the nitroxide polyanion is much higher as compared to the nitroxide polycation. LbL thin films of the nitroxide polyanion and nitroxide polycation are assembled, demonstrating linear growth and tunable thickness (28 nm/layer pair). This work confirms that the ion transport mechanism of the LbL films during the redox reaction is influenced depending on the charge of the terminating layer, where the nitroxide polyanion can participate in self-doping, which leads to a contribution from cation transport. The nitroxide polyanion-terminated film also exhibits a higher capacity and a slightly reduced charge transfer resistance. However, it was also observed that a more pronounced capacity fade occurred for the polyanion-terminated film than the polycation-terminated film. Taken together, this highlights how oppositely charged radical-containing polyelectrolytes can form electroactive coatings for possible applications in energy storage or sensing.

A new bis(catechol) monomer, namely, 4,4′-((1r,3r)-adamantane-2,2-diyl)bis(benzene-1,2diol) (THADM) was synthesized by condensation of 2-adamantanone with veratrole followed by demethylation of the formed (1r,3r)-2,2-bis(3,4 dimethoxyphenyl)adamantane. Polycondensation of THADM and various compositions of THADM and 5,5,6′,6′-tetrahydroxy-3,3,3′,3′-tetramethylspirobisindane was performed with 2,3,5,6-tetrafluoroterephthalonitrile (TFTPN) to obtain the homopolymer and copolymers. These polymers demonstrated good solubility in common organic solvents such as dichloromethane, chloroform, and tetrahydrofuran and could be cast into tough films from their chloroform solutions. GPC analysis revealed that number average molecular weights of polymers were in the range 48,100–61,700 g mol−1, suggesting the formation of reasonably high molecular weight polymers. They possessed intrinsic microporosity with Brunauer-Emmett-Teller (BET) surface area in the range 703–741 m2 g−1. Thermogravimetric analysis of polymers indicated that 10% weight loss temperature was in the range 513–518 °C demonstrating their excellent thermal stability. THADM-based polymer of intrinsic microporosity (PIM) showed P(CO2) = 1080, P(O2) = 232 and appreciable selectivity [α(CO2/CH4) = 22.6, α(CO2/N2) = 26.7, and α(O2/N2)= 5.7]. The gas permeability measurements revealed that with increase in the content of adamantane units in PIMs, selectivity increased and permeability decreased, following the trade-off relationship. The gas separation properties of PIMs containing adamantane units were located close to 2008 Robeson upper bound for gas pairs such as CO2/CH4, CO2/N2, H2/N2, and O2/N2. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017

Polymeric ionic liquids (PILs) have emerged as promising membrane materials for CO2 separation. The present work is aimed at investigating the effects of incorporation of rigid polyaromatic hydrocarbons, viz., pyrene and anthracene, in polybenzimidazole-based PILs. The effects of substituent and anion variation on the gas permeation properties of PILs using pure gases were examined at 20 atm upstream pressure. The results were correlated with physical properties of PILs. The pyrene substituted PIL exhibited ∼10 fold increase in CO2 permeability as compared to its precursor polymer PBI-BuI. The combination of a CO2 specific anion and bulky group substitution offered higher CO2 permeability as well as appreciable permselectivity than their structural analogue that was devoid of IL functionality. The permeation properties of present PILs were superior to those of conventional glassy polymers such as polysulfone, matrimid and polycarbonate which are widely studied for their gas permeation properties.

Polymeric ionic liquids (PILs) are emerging as promising membrane materials for CO 2 separation. Present work is in continuation with our earlier efforts on evaluating gas permeation properties (especially, CO 2 ) of film forming PILs based on polybenzimidazoles and efforts towards improving their permeability by structural tuning. This work specifically aims at evaluating effect of anion variation in chosen PILs possessing partial N -quaternization of imidazole moiety of PBI-BuI. Three anions (viz., Tf 2 N − , BF 4 − and Ac − ) were chosen for the bromide exchange of two PILs, viz., [TBzPBI-BuI][Br] 10 and [TBzPBI-BuI][Br] 18 , possessing degree of PBI N -quaternization (DQ) as 10 and 18%, respectively. Concurrent effects of variation in anion and DQ were analyzed in terms of physical and gas permeation properties of the resulting PILs. All of them possessed amorphous nature, adequate thermal stability (≥250 °C) and solvent solubility, which are primary requisites towards their applicability as a membrane material. PILs possessing BF 4 − anion exhibited improved CO 2 permeability coefficient as well as its permselectivity over CH 4 and N 2 , in comparison to their counterparts with other anions.

Polymeric Ionic Liquids (PILs) are being considered as promising membrane materials for CO 2 separation. Present work aims at investigating effects substitution asymmetry on imidazole moiety of two structurally different polybenzimidazoles (PBI-BuI and PBI-HFA) on physical, gas sorption and transport properties of the resulting film forming PILs possessing symmetric substitution, while keeping one of the N - substituent as methyl group. PILs were obtained with high degree of substitution. The halide anion of these PILs was exchanged with BF 4 ¯, Tf 2 N¯ and HFB¯ anions. Effects of substituents, cationic backbone and type of anions on gas permeation properties of PILs using pure gases (He, H 2 , N 2 and CO 2 ) were examined at 20 atm upstream pressure and correlated with their physical properties. Combination of typical ionic liquid character (effective towards enhancing CO 2 sorption) and looser chain packing (ease in gas diffusion) offered improved CO 2 permeation characteristics. As an outcome, some of the PILs exhibited higher CO 2 permeation than that of hydrogen, typically known as ‘reverse selectivity’. These asymmetrically substituted PILs enhanced not only the gas permeability, but also selectivity than their symmetrically substituted counterparts.

Catalytic activity of various solid acid catalysts is evaluated for the continuous hydroxyalkylation of p-cresol to [2,2′-methylenebis(4-methylphenol)] (DAM) in a fixed bed reactor. This is an industrially important process generally carried out in the presence of mineral acids. In the present study, we show that solid acids can be successfully used for this important process. The characterization of these solid acids is done using ammonia TPD measurement based on which the observed activity results can be explained. The performance of both batch and continuous operation has been studied for the hydroxyalkylation of p-cresol using the montmorillonite KSF/0 catalyst. The effect of reaction parameters such as mole ratio, temperature and catalyst concentration on the conversion of p-cresol and DAM selectivity have also been studied in both batch and fixed bed reactors. Significant difference is observed on the conversion of p-cresol and DAM selectivity with changing flow rate of reaction mixture in continuous operation.

We report, for the first time, applicability of film forming polymeric ionic liquids (PILs) possessing pyrene and anthracene fluorophores for the detection of nitroaromatics (NACs). These functionalized PILs were synthesized via post modification of thermo-chemically and mechanically stable polybenzimidazole (PBI). Formed PILs were evaluated for their ability to detect NACs through quenching of fluorescence intensity. Quenching of fluorescence intensity in solution state for NACs, such as nitrobenzene (NB), 2,4,6-trinitrotoluene (TNT) and picric acid (PA), was found to be rapid in both the PILs possessing pyrene and anthracene. The solution-phase Stern–Volmer quenching constants for PA were higher than for other NACs. After these promising results, self-standing films (∼12 μm thick) were also evaluated for fluorescence quenching by NACs as well as possible interferents of different nature. These films also exhibited rapid and selective fluorescence quenching when exposed to the saturated vapors of NACs at ambient temperature and pressure. Fluorescence emission of PIL films was affected little by the presence of commonly found interferents. Furthermore, fluorescence intensity could be recovered after the quenching, enabling the reuse of these PIL films for detection of NACs. Smart performance of these films and ease of preparation qualify them as attractive candidates in developing sensor devices for sensitive NACs detection in presence of possible interferents.