@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: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:000373163100005, title = {Chemically stable covalent organic framework (COF)-polybenzimidazole hybrid membranes: enhanced gas separation through pore modulation}, journal = {Chemistry-A European Journal}, volume = {22}, number = {14}, year = {2016}, month = {MAR}, pages = {4695-4699}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {

Highly flexible, TpPa-1@PBI-BuI and TpBD@PBI-BuI hybrid membranes based on chemically stable covalent organic frameworks (COFs) could be obtained with the polymer. The loading obtained was substantially higher (50\%) than generally observed with MOFs. These hybrid membranes show an exciting enhancement in permeability (about sevenfold) with appreciable separation factors for CO2/N-2 and CO2/CH4. Further, we found that with COF pore modulation, the gas permeability can be systematically enhanced.

}, keywords = {covalent organic frameworks, Gas separation, membranes, microporous materials, pore modulation}, issn = {0947-6539}, doi = {10.1002/chem.201504836}, author = {Biswal, Bishnu P. and Chaudhari, Harshal D. and Banerjee, Rahul 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.} }