@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.} }