@article { ISI:000242988100022, title = {Enhancement of gas permeation properties of polybenzimidazoles by systematic structure architecture}, journal = {Journal of Membrane Science}, volume = {286}, number = {1-2}, year = {2006}, month = {DEC}, pages = {161-169}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Systematic structural variations in thermally stable polybenzimidazole (PBI) are explored that led to a substantial improvement in gas permeation properties. Physical property determinations revealed that incorporation of hexafluoroisopropylidene and tert-butyl groups led to amorphous polymers with slightly lowered thermal stability and decreased chain packing. PBI based on 4,4{\textquoteright}-(hexafluoroisopropylidene)bis(benzoic acid) and 5-tert-butyl isophthalic acid exhibited 10-40 times higher permeability, while changes in selectivities for industrially important pairs ranged from modest decrease of 75\% or less than that of PBI based on isophthalic acid. The O-2/N-2 selectivity was almost doubled in case of PBI based on 5-tert-butyl isophthalic acid. Gas diffusion coefficients were estimated from solubility and permeability coefficient determinations. These, along with dual-mode sorption parameters estimated from sorption isotherms provided an insight towards variations in permeation behavior. The permeability predictions for heavier gases in isophthalic acid based PBI correlated well with physical properties. The occurrence of permeation characteristics (especially P-H2 and P-H2/P-N2) near Robeson{\textquoteright}s upper bound, high thermal stability and good solvent solubility achieved by these structural modifications depicted the potential of this family of polymers as gas separation membrane materials. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {Diffusion, Gas permeation, Polybenzimidazole, Sorption, thermal stability}, issn = {0376-7388}, doi = {10.1016/j.memsci.2006.09.030}, author = {Kumbharkar, Santosh C. and Karadkar, Prasad B. and Kharul, Ulhas K.} } @article { ISI:000251722700028, title = {Assessing feasibility of polyarylate-clay nanocomposites towards improvement of gas selectivity}, journal = {Journal of Membrane Science}, volume = {306}, number = {1-2}, year = {2007}, month = {DEC}, pages = {277-286}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Polymer-clay nanocomposites are well known to reduce the penetrant permeability by following tortuous path. Effects of such reduction in gas permeability on variation in selectivity of nanocomposites prepared using a high permeability polymer were examined. The polyarylate: poly (tetramethyl bisphenolA-iso/terephthalate) that exhibits high permeability and moderate selectivity was chosen for making nanocomposites with two organically modified clays (Cloisite 6A and 10A) by solution intercalation method. The nanocomposite formation for various clay loadings (3, 5 and 7\% w/w) in polyarylate was ascertained by change in physical properties (X-ray diffraction, DMA, TEM). Behavior of solution viscosity and nanocomposite density indicated existence of polymer-clay layer interactions. As anticipated, though the gas permeability of pure gases, viz., He, N-2, CH4 and CO2 exhibited decrease, it was not monotonous. This decrease was more for larger gases (N-2, CH4 and CO2) in comparison to the decrease for smaller gas (He) permeability. This led to a decrease in CO2/N-2 and CO2/CH4 selectivities and increase in He/CO2 selectivity; while He/CH4 selectivity was increased substantially at 7\% clay loading. This variation indicated feasibility of nanocomposites formation as a tool for improving selectivity of certain gas pairs. (c) 2007 Elsevier B.V. All rights reserved.

}, keywords = {Gas permeation, Nanocomposites, polyarylates, selectivity, solution intercalation}, issn = {0376-7388}, doi = {10.1016/j.memsci.2007.09.001}, author = {Bhole, Yogesh S. and Wanjale, Santosh D. and Kharul, Ulhas K. and Jog, Jyoti Prakash} } @article { ISI:000251631200005, title = {Effect of substituent polarity, bulk, and substitution site toward enhancing gas permeation in dibromohexafluorobisphenol-A based polyarylates}, journal = {Journal of Polymer Science Part B-Polymer Physics}, volume = {45}, number = {23}, year = {2007}, month = {DEC}, pages = {3156-3168}, publisher = {JOHN WILEY \& SONS INC}, type = {Article}, address = {111 RIVER ST, HOBOKEN, NJ 07030 USA}, abstract = {

The gas permeation properties of polyarylates were tuned by varying nature and site of substituents present on both of its monomers, viz., bisphenol and dicarboxylic acid. The phenyl rings of hexafluorobisphenol-A were substituted in asymmetric manner by polar bromine to obtain dibromohexafluorobisphenol-A. This bisphenol was polymerized with equimolar mixture of iso- and terephthalic acid (base case), bromo- and nitroterephthalic acid (polar group substituted acids), 4,4{\textquoteright}-hexafluoroisopropylidene bis(benzoic acid), and t-butyl isophthalic acid (bulky group containing acids). Physical properties and gas permeation properties of these polyarylates were investigated to assess combined effects of asymmetric nature of bisphenol substitution, polar nature of substituent bromine, hexafluoroisopropylidene group present at the bridge position of bisphenol, and substituent present on the acid moiety. The combination of these substituent types led these polyarylates to lie near Robeson upper bound. The gas sorption analysis and estimation of diffusivity in these polyarylates shed a light on observed variations in gas permeation properties by attempted structural variations. (c) 2007 Wiley Periodicals, Inc.

}, keywords = {asymmetric substitution, Diffusion, Gas permeation, gas sorption, polyarylates, selectivity, structure-property relations}, issn = {0887-6266}, doi = {10.1002/polb.21314}, author = {Ishole, Yogesh S. and Karadkar, Prasad R. and Kharul, Ulhas K.} } @article { ISI:000250356300015, title = {Gas permeation in amine functionalized silicon rubber membranes}, journal = {Separation and Purification Technology}, volume = {57}, number = {2}, year = {2007}, month = {OCT}, pages = {304-313}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Silicon rubber (SR) based thin film composite (TFC) membranes find increasing applicability in various industrial separations owing to its excellent thermal and chemical stability. The functionalization of SR would provide enhanced separation characteristics for certain separation applications. The present research focuses on gas permeation properties of dense and thin film composite membranes based on amine substituted silicon rubber (ASR) and unsubstituted silicon rubber (SR). The dense membrane sorption analysis indicated that presence of amine functionality in ASR increased pressure dependant CO2 sorption capacity. Owing to this, an elevation Of CO2 permeability by 15\% and CO2 based selectivities by 22-34\% in comparison to that of unsubstituted SR was observed. The TFC membranes with SR and ASR as the selective layer on the top of different ultrafiltration (UF) supports with varying properties based on polyacrylonitrile and polysulfone were prepared. The effects of crucial parameters that affected TFC membrane performance, viz., coating solution concentration, UF support membrane porosity and nature of materials were investigated. The preparation of ASR based TFC membranes was demonstrated with a simple crosslinking agent-glutaraldehyde while analyzing effects of crosslinking time on their permeation properties. Polyacrylonitrile (PAN) was found to be better support layer material for ASR based TFC formation than polysulfone (PSF). Thin defect free coating layer can be obtained by appropriate combination of coating solution concentration and support UF membrane porosity. The analysis of effective skin layer thickness of TFC membranes indicated that careful optimization of these parameters is necessary to achieve defect free TFC membranes possessing a good combination of permeance and selectivity. (C) 2007 Elsevier B.V. All rights reserved.

}, keywords = {Carbon dioxide, Gas permeation, silicon rubber, thin film composite membrane}, issn = {1383-5866}, doi = {10.1016/j.seppur.2007.05.002}, author = {Achalpurkar, Manoj P. and Kharul, Ulhas K. and Lohokare, Harshada R. and Karadkar, Prasad B.} } @article { ISI:000255339200058, title = {Synthesis, characterization, and gas permeability of aromatic polyimides containing pendant phenoxy group}, journal = {Journal of Applied Polymer Science}, volume = {108}, number = {6}, year = {2008}, month = {JUN}, pages = {3881-3889}, publisher = {JOHN WILEY \& SONS INC}, type = {Article}, address = {111 RIVER ST, HOBOKEN, NJ 07030 USA}, abstract = {

A diamine containing a pendant phenoxy group, 1-phenoxy-2,4-diaminobenzene, was synthesized and condensed with different aromatic dianhydrides [4,4{\textquoteright}-oxydiphthalic dianhydride, 4,4{\textquoteright}-(hexafluoroisopropylidene)diphthalic anhydride, 3,3{\textquoteright},4,4-benzophenone tetracarboxylic dianhydride, 3,3{\textquoteright},4,4{\textquoteright}-biphenyltetracorboxylic dianhydride, and pyromellitic dianhydride] by one-step synthesis at a high temperature in m-cresol to obtain polyimides in high yields. Most of the polyimides exhibited good solvent solubility and could be readily dissolved in chloroform, sym-tetrachloroethane, N,N-dimethylformamide, NN-dimethylacetamide, and nitrobenzene. Their inherent viscosities were in the range of 0.33-1.16 dL/g. Wide-angle X-ray spectra revealed that these polymers were amorphous in nature. All these polyimides were thermally stable, having initial decomposition temperatures above 500 degrees C and glass-transition temperatures in the range of 248-281 degrees C. The gas permeability of 4,4{\textquoteright}-oxydiphthalic dianhydride and 4,4{\textquoteright}-(hexafluoroisopropylidene)diphthalic anhydride based polyimides was investigated with pure gases: He, H-2, O-2, Ar, N-2, CH4, and CO2. A polyimide containing a -C(CF3)(2)- linkage showed a good combination of permeability and selectivity. (C) 2008 Wiley Periodicals, Inc.

}, keywords = {Gas permeation, membranes, polyimides, selectivity, structure-property relations}, issn = {0021-8995}, doi = {10.1002/app.28074}, author = {Kothawade, Sandeep S. and Kulkarni, Mahesh P. and Kharul, Ulhas K. and Patil, Anandrao S. and Vernekar, Subhash P.} } @article { ISI:000272871400006, title = {N-substitution of polybenzimidazoles: synthesis and evaluation of physical properties}, journal = {European Polymer Journal}, volume = {45}, number = {12}, year = {2009}, month = {DEC}, pages = {3363-3371}, publisher = {PERGAMON-ELSEVIER SCIENCE LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND}, abstract = {

Series of N-substituted polybenzimidazoles (PBI) were synthesized using selective alkyl groups with varying bulk and flexibility, viz., methyl, n-butyl, methylene trimethylsilane and 4-tert-butylbenzyl. PBl-I based on 3,3{\textquoteright}-diaminobenzidine (DAB) and isophthalic acid and PBI-Bul based on DAB and 5-tert-butyl isophthalic acid were chosen for N-substitution. Structural characterizations of substituted polymers by FT-IR and (1)H NMR revealed elimination of hydrogen bonding. Evaluation of their physical properties revealed that N-substitution rendered better solvent solubility in common organic solvents, more open polymer matrix, but reduced thermal properties in comparison to their respective parent PBI. 4-tert-butylbenzyl, methylene trimethylsilane or n-butyl group substituted polymers were soluble even in chlorinated solvents (CHCl(3) and TCE). Substantial variations in gas permeability of inert gases, He and Ar and attractive P(He)/P(Ar) selectivity, especially after methyl group substitution depicted potential of these materials for gas separation. (C) 2009 Elsevier Ltd. All rights reserved.

}, keywords = {Gas permeation, hydrogen bonding, N-Substitution, Polybenzimidazole}, issn = {0014-3057}, doi = {10.1016/j.eurpolymj.2009.10.006}, author = {Kumbharkar, Santosh C. and Kharul, Ulhas K.} } @article { ISI:000278905100015, title = {Investigation of gas permeation properties of systematically modified polybenzimidazoles by N-substitution}, journal = {Journal of Membrane Science}, volume = {357}, number = {1-2}, year = {2010}, month = {JUL}, pages = {134-142}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Gas permeation behavior of a series of thermally stable N-substituted polybenzimidazoles by systematically varying bulk and flexibility of the substituent was investigated. Two different PBIs having variation in their acid moiety, viz., PBI-I (based on isophthalic acid) and PBI-BuI (based on 5-tert-butyl isophthalic acid) were selected for N-substitution by alkyl groups possessing different bulk and flexibility. These substituent groups were methyl, n-butyl, methylene trimethylsilane and 4-tert-butylbenzyl. Pure gas sorption and permeability using H(2), N(2), O(2), CH(4) and CO(2) were investigated and correlated with physical properties of formed polymers. Estimation of dual-mode sorption parameters, coefficients of sorption, permeability and diffusion for different gases provided an insight towards effects of nature of a substituent group and parent PBI on governing gas sorption and permeation properties. By changing the substituent group, diffusivity coefficients was found to vary to a larger extent than the solubility coefficient. This significantly enhanced gas permeability for different gases by 1.2-129 times than that of parent PBIs. The permselectivity P(O2)/P(N2) was increased (up to 237\%), while for other gas pairs, it was decreased to a different extent. (C) 2010 Elsevier B.V. All rights reserved.

}, keywords = {Diffusion, Gas permeation, N-Substitution, Polybenzimidazole, Sorption}, issn = {0376-7388}, doi = {10.1016/j.memsci.2010.04.014}, author = {Kumbharkar, Santosh C. and Kharul, Ulhas K.} } @article { ISI:000280311500048, title = {New N-substituted ABPBI: synthesis and evaluation of gas permeation properties}, journal = {Journal of Membrane Science}, volume = {360}, number = {1-2}, year = {2010}, month = {SEP}, pages = {418-425}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Aromatic poly(2,5-benzimidazole), ABPBI was post-modified for the first time to produce organosoluble N-substituted ABPBI. This modification was carried out by N-substitution of ABPBI with bulky alkyl groups, viz., 4-tert-butylbenzyl and methylene trimethylsilyl in an attempt to utilize high rigidity of ABPBI towards gas permeation. These substituted polymers exhibited solubility in common organic solvents, enhancing their processability than ABPBI, which is soluble only in acidic solvents. Considerable decrease in chain packing density led to increase in gas sorption as that of unsubstituted ABPBI. The permeability of pure gases of commercial significance (He, H(2), N(2), O(2), CH(4) and CO(2)) were high, coupled with attractive selectivities. In comparison to conventional PBI, methylene trimethylsilyl substituted ABPBI led to considerably high (33 folds) CO(2) permeability with almost similar selectivity (P(CO2)/P(N2) approximate to 33). Feasibility of these N-substituted ABPBIs to be converted in to required membrane form along with its considerably higher permeation properties depicted the potential of this polymer to be used as gas separation material. Gas diffusion coefficients were estimated from solubility and permeability coefficient. These, along with dual-mode sorption parameters estimated from sorption isotherms provided an insight towards variations in permeation behavior caused by the substitution. (C) 2010 Elsevier B.V. All rights reserved.

}, keywords = {5-benzimidazole), Diffusion, Gas permeation, N-Substitution, Poly(2, Sorption}, issn = {0376-7388}, doi = {10.1016/j.memsci.2010.05.041}, author = {Kumbharkar, Santosh C. and Kharul, Ulhas K.} } @article { ISI:000274348100003, title = {Polyarylate based thin film composite (TFC) membranes: effects of coating parameters, gutter layer, and intrinsic material properties}, journal = {Separation Science and Technology}, volume = {45}, number = {2}, year = {2010}, month = {JAN}, pages = {163-171}, publisher = {TAYLOR \& FRANCIS INC}, address = {325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USA}, abstract = {

Investigations in thin film composite (TFC) membrane formation with polyacrylonitrile ultrafiltration membrane as a support and three polyarylates with sequentially increased polarity are reported. Effects of TFC membrane preparation parameters viz., concentration of the coating solution, dip time, presence of solvent in pores of UF membrane support, and presence of the gutter layer were examined towards the formation of the selective skin layer, which was assessed by gas permeation analysis. TFC membranes prepared using dimethyl bisphenol-A based polyarylate exhibited similar to 3 orders of magnitude higher permeability and comparable selectivity as that of its dense membrane.

}, keywords = {Gas permeation, gutter layer, polarity, polyarylates, TFC membrane}, issn = {0149-6395}, doi = {10.1080/01496390903423089}, author = {Chendake, Yogesh J. and Bhole, Yogesh S. and Lohokare, Harshada R. and Kharul, Ulhas K.} } @article { ISI:000287058200053, title = {Polybenzimidazoles based on 3,3 {\textquoteleft}-diaminobenzidine and aliphatic dicarboxylic acids: synthesis and evaluation of physicochemical properties toward their applicability as proton exchange and gas separation membrane material}, journal = {Journal of Applied Polymer Science}, volume = {120}, number = {2}, year = {2011}, month = {APR}, pages = {1090-1099}, publisher = {WILEY-BLACKWELL}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {

A series of aromatic-aliphatic polybenzimidazoles (PBIs) based on 3,3{\textquoteright}-diaminobenzidine (DAB) and aliphatic dicarboxylic acid with incremental -CH2- groups were synthesized. Optimization of synthesis parameters and evaluation of physicochemical properties are requisite for PBI applicability as the proton exchange membrane (PEM) and gas separation membrane materials are reported. It was found that though all these PBIs exhibited high thermal, mechanical, and oxidative stability, effect of added flexibility on physical properties is not monotonous. Membranes were prepared by solution casting as well as phase-inversion method. The later types of membranes exhibited much higher H3PO4 content than its doping achieved in the solution casted membranes. These PBIs possess low hydrogen and helium permeability than that of conventional PBI. This low permeability, along with their excellent oxidative stability indicated that they can be promising PEM materials. Their CO2-sorption analysis revealed that PBI6 based on suberic acid possesses appreciable CO2 sorption. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 1090-1099, 2011

}, keywords = {Gas permeation, mechanical properties, membranes, oxidative stability, polybenzimidazoles}, issn = {0021-8995}, doi = {10.1002/app.33246}, author = {Bhavsar, Rupesh S. and Nahire, Sandip B. and Kale, Mrunali S. and Patil, Shubhangi G. and Aher, Pradnya P. and Bhavsar, Ritesh A. and Kharul, Ulhas K.} } @article { ISI:000341141800050, title = {Investigation of gas permeation properties of film forming polymeric ionic liquids (PILs) based on polybenzimidazoles}, journal = {Journal of Membrane Science}, volume = {470}, year = {2014}, month = {NOV}, pages = {494-503}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Polymeric ionic liquids (PILs) are emerging as new generation membrane materials for CO2 separation. Gas permeation properties of a recently developed PIL family based on three structurally different polybenzimidazoles (PBIs) possessing excellent film forming characteristics are reported. Effects of cationic backbone and anions on gas permeation properties of PILs using pure gases (He, H-2, N-2, CH4, and CO2) were examined at 20 atm upstream pressure and correlated with their physical properties. In comparison to the parent PBIs, PILs exhibited generally higher CO2 permeability, without largely affecting CO2 based selectivity. Some of these PILs exhibiting high PCO2/PCH4, selectivity and P-H2/P-CO2, approaching similar to 1 indicated dominance of CO2 sorption over diffusion. The CO2 sorption specificity of these PILs was distinctly observed based on their improved S-CO2/S-N2, S-CO2/S-CH4 and S-CO2/S-H2 selectivity than their parent PBIs. A large variation in permeation properties of PILs based on a common polycation but different anions indicated that anions play a crucial role on governing gas permeation properties of these PILs. (C) 2014 Elsevier B.V. All rights reserved

}, keywords = {Gas permeation, Membranes for CO2 separation, Polybenzimidazole, Polymeric ionic liquid}, issn = {0376-7388}, doi = {10.1016/j.memsci.2014.07.076}, author = {Bhavsar, Rupesh S. and Kumbharkar, Santosh C. and Kharul, Ulhas K.} } @article { ISI:000350856400003, title = {Polybenzimidazole based polymeric ionic liquids (PILs): effects of controlled degree of N-quaternization on physical and gas permeation properties}, journal = {Journal of Membrane Science}, volume = {481}, year = {2015}, month = {MAY}, pages = {19-27}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Polymeric ionic liquids (PILs) are gaining increasing attention as potential membrane materials to be employed for CO2 separation. With a goal to improve gas permeability, this work presents a series of film forming PlLs obtained by controlled degree of N-quaternization (DQ) of PBI-BuI using a bulky 4-tertbutylbenzyl group. Concurrent effects of variation in ionic content and bulky group substitution were analyzed for physical and gas permeation properties of the resulting PILs. Attempted structural variations leading to simultaneous increments in ionic content and bulky groups offered amorphous polymers with acceptable thermal stability and non-monotonous chain packing density. Enhancement in pure gas permeability coupled with appreciable selectivity for various gas pairs was in accordance with the packing density variations in the series. Gas permeability showed maxima at DQ of just 13\%. This conveyed that effects of bulky group substitution in retarding chain packing are overcome by attractive ionic interactions at much lower DQ in these PILs ionic interactions are thus more predominant in governing chain packing and gas permeation properties. These PILs possessed 3.3-20 times higher CO2 permeability in comparison to their parent PBI-BuI, without a significant loss in selectivity. (C) 2015 Elsevier B.V. All rights reserved.

}, keywords = {Degree of quaternization, Gas permeation, Polybenzimidazole, Polymeric ionic liquid}, issn = {0376-7388}, doi = {10.1016/j.memsci.2015.02.004}, author = {Rewar, Anita S. and Bhavsar, Rupesh S. and Sreekumar, K. and Kharul, Ulhas K.} } @article { ISI:000375647900005, title = {Incorporation of rigid polyaromatic groups in polybenzimidazole-based polymeric ionic liquids: assertive effects on gas permeation properties}, journal = {Polymer}, volume = {93}, year = {2016}, month = {JUN}, pages = {30-36}, publisher = {ELSEVIER SCI LTD}, address = {THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLAND}, abstract = {

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 similar to 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. (C) 2016 Elsevier Ltd. All rights reserved.

}, keywords = {Gas permeation, membranes, Polymeric ionic liquids}, issn = {0032-3861}, doi = {10.1016/j.polymer.2016.03.093}, author = {Shaligram, Sayali V. and Rewar, Anita S. and Wadgaonkar, Prakash P. and Kharul, Ulhas K.} } @article {44241, title = {Synthesis, characterization, and gas permeation properties of adamantane-containing polymers of intrinsic microporosity}, journal = {Journal of Polymer Science Part A-Polymer Chemistry}, volume = {56}, year = {2018}, month = {JAN }, pages = {16-24}, type = {Article}, abstract = {

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 gmol(-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 m(2)g(-1). Thermogravimetric analysis of polymers indicated that 10\% weight loss temperature was in the range 513-518 degrees C demonstrating their excellent thermal stability. THADM-based polymer of intrinsic microporosity (PIM) showed P(CO2)=1080, P(O-2)=232 and appreciable selectivity [(CO2/CH4)=22.6, (CO2/N-2)=26.7, and (O-2/N-2)= 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/N-2, H-2/N-2, and O-2/N-2. (c) 2017 Wiley Periodicals, Inc.

}, keywords = {adamantane, Gas permeation, intrinsic microporosity, membranes, structure-property relations}, issn = {0887-624X}, doi = {10.1002/pola.28710}, author = {Shrimant, Bharat and Shaligram, Sayali V. and Kharul, Ulhas K. and Wadgaonkar, Prakash P.} } @article {44180, title = {ZIF-8@DBzPBI-BuI composite membranes for olefin/paraffin separation}, journal = {Journal of Membrane Science}, volume = {549}, year = {2018}, month = {MAR }, pages = {38-45}, type = {Article}, abstract = {ZIF-8 is a member of Zeolitic Imidazole Framework family having high internal surface area, the high thermo-chemical stability and ease of synthesis gained immense attention for its highly selective sieving ability. Transforming it into a membrane form and practical utility remains a challenge. Any success towards this direction would radically reduce the cost of propylene/propane separation. Present study reports use of substituted polybenzimidazole (DBzPBI-BuI) for fabrication of flexible, thus scalable composite membranes with ZIF-8 (ZIF8@DBzPBI-BuI) possessing host-guest compatibility. The membrane with 30\% ZIF-8 loading showed promising propylene-propane separation (ideal selectivity of 32.7), coupled with propylene permeability of 12.13 Barrer. Analysis of sorption shed light on the high contribution of diffusivity on governing permeation properties of the composite membranes. The mixed gas analysis offered highly encouraging results in comparison to known composite membranes of different polymers with ZIF-8. Placement of present data on {\textquoteleft}upper-bound{\textquoteright} showed a rapid enhancement in selectivity by the addition of ZIF-8 in the polymer matrix, which seems to be a result of the elimination of inter-phase defects. It was made possible due to the functionality of host polymer.}, keywords = {Gas permeation, Olefin/paraffin separation, Polybenzimidazole (PBI), ZIF-8}, issn = {0376-7388}, doi = {10.1016/j.memsci.2017.11.069}, author = {Kunjattu, Shebeeb H. and Ashok, Varsha and Bhaskar, Anand and Pandare, Kiran and Banerjee, Rahul and Kharul, Ulhas K.} }