@article { ISI:000239445500108, title = {Surface modification of polyacrylonitrile based ultrafiltration membrane}, journal = {Journal of Applied Polymer Science}, volume = {101}, number = {6}, year = {2006}, month = {SEP}, pages = {4378-4385}, publisher = {JOHN WILEY \& SONS INC}, type = {Article}, address = {111 RIVER ST, HOBOKEN, NJ 07030 USA}, abstract = {

Ultrafiltration membrane based on polyacrylonitrile prepared by phase inversion method using zinc chloride as an additive showed more than 90\% rejection for BSA and 90-110 Im(-2) h(-1) water flux. The surface modification of this membrane was studied using ethanolamine, triethylamine, sodium hydroxide, and potassium hydroxide solutions. The effect of base treatment time and temperature on water flux and rejection was investigated. The membranes exhibited swelling by NaOH treatment followed by deswelling by HCl post-treatment, similar to pH responsive membranes. The treatment by organic as well as inorganic bases improved water flux with a slight lowering in BSA rejection by dead-end mode type treatment. A 230\% increase in water flux was achieved by sodium hydroxide treatment in crossflow mode without a noticeable pore swelling by SEM. The contact angle of the modified membranes was decreased as compared to the unmodified one indicating appreciable surface modification. As the treatment time or temperature increased, the ESCA analysis showed increased population of Na-carboxylate groups. (c) 2006 Wiley Periodicals, Inc.

}, keywords = {BSA rejection, chemical treatment, polyacrylonitrile membrane, surface modification, Ultrafiltration}, issn = {0021-8995}, doi = {10.1002/app.23917}, author = {Lohokare, Harshada R. and Kumbharkar, S. C. and Bhole, Yogesh S. and Kharul, Ulhas K.} } @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:000264521700002, title = {Selective synthesis of cumene by isopropylation of benzene using catalytic membrane reactor}, journal = {Chemical Engineering Journal}, volume = {147}, number = {2-3}, year = {2009}, month = {APR}, pages = {97-101}, publisher = {ELSEVIER SCIENCE SA}, address = {PO BOX 564, 1001 LAUSANNE, SWITZERLAND}, abstract = {

Selective isopropylation of benzene to cumene is demonstrated using catalytic membrane reactor (CMR), to our knowledge for the first time and the performance was evaluated against conventional plug flow reactor (PFR). Almost complete elimination of byproducts like polyalkylated benzene and higher aromatics could be made possible by using CMR. These are present in significant amount when reaction is carried out with PFR. The cumene selectivity increased up to a maximum of 97.25\% by CMR as against 90.05\% with conventional PFR. The effect of reaction parameters that can greatly influence the process economics, such as liquid hourly space velocity (LHSV), reactant mole ratio and catalyst/reactor volume ratio were investigated. Changes in these parameters made for CMR are industrially advantageous. The process by CMR is more economical and ecofriendly than PFR as far as milder process parameters (higher LHSV, lower reactant feed mole ratio, less catalyst require, etc.) and process intensification (reaction and separation in single reactor) are concerned. The study provides new insights for benzene isopropylation reaction. (C) 2008 Elsevier B.V. All rights reserved.

}, keywords = {Benzene, Catalytic membrane reactor, cumene, Diisopropyl benzene, Friedel-Craft alkylation}, issn = {1385-8947}, doi = {10.1016/j.cej.2008.06.035}, author = {Bokade, Vijay V. and Kharul, Ulhas K.} } @article { ISI:000352905700046, title = {Selective interfacial synthesis of metal-organic frameworks on a polybenzimidazole hollow fiber membrane for gas separation}, journal = {Nanoscale}, volume = {7}, number = {16}, year = {2015}, month = {MAR}, pages = {7291-7298}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Metal-organic frameworks (MOFs) have gained immense attention as new age materials due to their tuneable properties and diverse applicability. However, efforts on developing promising materials for membrane based gas separation, and control over the crystal growth positions on polymeric hollow fiber membranes still remain key challenges. In this investigation, a new, convenient and scalable room temperature interfacial method for growing MOFs (ZIF-8 and CuBTC) on either the outer or inner side of a polybenzimidazole based hollow fiber (PBI-BuI-HF) membrane surface has been achieved in a controlled manner. This was made possible by the appropriate selection of an immiscible solvent pair and the synthetic conditions. The growth of MOFs on the PBI-BuI-HF membrane by the interfacial method was continuous and showed an appreciable gas separation performance, conveying promise for their applicability.

}, issn = {2040-3364}, doi = {10.1039/c5nr00299k}, author = {Biswal, Bishnu P. and Bhaskar, Anand and Banerjee, Rahul and Kharul, Ulhas K.} } @article { ISI:000373492800012, title = {Synthesis and properties of poly(arylene ether)s based on 3-pentadecyl 4,4{\textquoteright}-biphenol}, journal = {Polymer International}, volume = {65}, number = {5}, year = {2016}, month = {MAY}, pages = {567-576}, publisher = {WILEY-BLACKWELL}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {

A new biphenol, 3-pentadecyl 4,4-biphenol, was synthesized starting from 3-pentadecylphenol and was polycondensed with 4,4-difluorobenzophenone, 1,3-bis(4-fluorobenzoyl)benzene and bis(4-fluorophenyl)sulfone to obtain poly(arylene ether)s with biphenylene linkages in the backbone and pendent pentadecyl chains. Inherent viscosities and number-average molecular weights (M-n) of the poly(arylene ether)s were in the range 0.50 - 0.81 dL g(-1) and 2.2 x 10(4) - 8.3 x 10(4), respectively. Detailed NMR spectroscopic studies of the poly(arylene ether)s indicated the presence of constitutional isomerism which existed because of the non-symmetrical structure of 3-pentadecyl 4,4-biphenol. The poly(arylene ether)s readily dissolved in common organic solvents such as dichloromethane, chloroform and tetrahydrofuran and could be cast into tough, transparent and flexible films from their chloroform solutions. The poly(arylene ether)s exhibited T-g values in the range 35-60 degrees C which are lower than that of reference poly(arylene ether)s without pentadecyl chains. The 10\% decomposition temperatures (T-10) of the poly(arylene ether)s were in the range 410-455 degrees C indicating their good thermal stability. A gas permeation study of poly(ether sulfone) containing pendent pentadecyl chains revealed a moderate increase in permeability for helium, hydrogen and oxygen. However, there was a large increase in permeability for carbon dioxide which could be attributed to the internal plasticization effect of pendent pentadecyl chains. (c) 2016 Society of Chemical Industry

}, keywords = {cashew nut shell liquid (CNSL), gas permeation study, pentadecyl, poly(arylene ether)s, thermal stability}, issn = {0959-8103}, doi = {10.1002/pi.5095}, author = {Tawade, Bhausaheb V. and Shaligram, Sayali V. and Valsange, Nitin G. and Kharul, Ulhas K. and Wadgaonkar, Prakash P.} } @article { ISI:000371453700057, title = {Self-exfoliated guanidinium-based ionic covalent organic nanosheets (iCONs)}, journal = {Journal of the American Chemical Society}, volume = {138}, number = {8}, year = {2017}, month = {MAR}, pages = {2823-2828}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Covalent organic nanosheets (CONs) have emerged as functional two-dimensional materials for versatile applications. Although pi-pi stacking between layers, hydrolytic instability, possible restacking prevents their exfoliation on to few thin layered CONs from crystalline porous polymers. We anticipated rational designing of a structure by intrinsic ionic linker could be the solution to produce self-exfoliated CONs without external stimuli. In an attempt to address this issue, we have synthesized three self-exfoliated guanidinium halide based ionic covalent organic nanosheets (iCONs) with antimicrobial property. Self-exfoliation phenomenon has been supported by molecular dynamics (MD) simulation as well. Intrinsic ionic guanidinium unit plays the pivotal role for both self-exfoliation and antibacterial property against both Gram-positive and Gram-negative bacteria. Using such iCONs, we have devised a Mixed matrix membrane which could be useful for antimicrobial coatings with plausible medical benefits.

}, issn = {0002-7863}, doi = {10.1021/jacs.5b13533}, author = {Mitra, Shouvik and Kandambeth, Sharath and Biswal, Bishnu P. and Khayum, Abdul M. and Choudhury, Chandan Kumar and Mehta, Mihir R. and Kaur, Gagandeep and Banerjee, Subhrashis and Prabhune, Asmita and Verma, Sandeep and Roy, Sudip and Kharul, Ulhas K. and Banerjee, Rahul} } @article {45418, title = {Spiro [fluorene-9,9 {\textquoteright}-xanthene]-containing copolymers of intrinsic microporosity: synthesis, characterization and gas permeation properties}, journal = {Reactive \& Functional Polymers}, volume = {133}, year = {2018}, month = {2018}, pages = {153-160}, type = {Article}, abstract = {In the present study, a new bis(catechol) containing spiro[fluorene-9,9{\textquoteright}-xanthene], namely, 4,4{\textquoteright}-(spiro(fluorene9,9{\textquoteright}-xanthene]-2{\textquoteright},7{\textquoteright}-diyl)bis(benzene-1,2-diol) (THSFX) was designed and synthesized. Polycondensation reactions of THSFX and varying compositions of THSFX and 5,5{\textquoteright},6,6{\textquoteright}-tetrahydroxy-3,3,3{\textquoteright},3{\textquoteright}-tetramethyl-1,1{\textquoteright}-spirobisindane (TTSBI) were carried out with 2,3,5,6-tetrafluoroterephthalonitrile (TFTPN) to obtain a homopolymer and copolymers, respectively. The organo-soluble polymers exhibited reasonably high molecular weights (23300-34,100 g/mol) and could be cast into self-standing films from their chloroform solutions. X-Ray diffraction studies indicated that PIMs were amorphous in nature. These polymers exhibited high thermal stability (T-10 = 490-510 degrees C) and possessed intrinsic microporosity with high BET surface area (360-796 m(2)/g). The gas permeation properties of SFX-PIM-25 and SFX-PIM-33 were evaluated and they exhibited high gas permeability (CO2 = 3595-4034 Barrer). The gas permeability data of SFX-PIM-25 and SFX-PIM-33 was located close to 1991 Robson upper bound for CO2/N-2, CO2/CH4 and O-2/N-2 gas pairs}, issn = {1381-5148 }, doi = {10.1016/j.reactfunctpolym.2018.10.008}, author = {Shrimant, Bharat and Kharul, Ulhas K. and Wadgaonkar, Prakash P.} } @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 {49034, title = {Scalable, interfacially synthesized, covalent-organic framework (COF)-based thin-film composite (TFC) hollow fiber membranes for organic solvent nanofiltration (OSN)}, journal = {ACS Applied Materials and Interfaces }, volume = {16}, year = {2024}, month = {APR}, pages = {19463-19471}, type = {Article}, abstract = {

Covalent organic frameworks have great potential for energy-efficient molecular sieving-based separation. However, it remains challenging to implement COFs as an alternative membrane material due to the lack of a scalable and cost-effective fabrication mechanism. This work depicts a new method for fabricating a scalable in situ COF hollow fiber (HF) membrane by an interfacial polymerization (IP) approach at room temperature. The 2D COF film was constructed on a polyacrylonitrile HF substrate using aldehyde (1,3,5-trimethylphloroglucinol, Tp) and amine (4,4 {\textquoteleft}-azodianiline (Azo) and 4,4 {\textquoteleft},4 {\textquoteleft}{\textquoteright}-(1,3,5-triazine- 2,4,6-triyl) trianiline (Tta)) as precursors. The COF membrane on the PAN substrate showed 99\% rejection of Direct red-80 with remarkable solvent permeance. The rejection analysis revealed that the structural aspects of the solute molecule play a major role in rejection rather than the molecular weight. We further optimized the precursor concentrations to improve the permeation performance of the resulting membrane. The durability study reveals excellent stability of the membrane toward organic solvents. This study also demonstrated the easy scalability of the membrane fabrication approach. The approach was further extrapolated to fabricate a cation-based COF membrane. These charged membranes exhibited an enhanced rejection performance. Finally, this approach can facilitate industrially challenging molecular sieving applications using COF-based membranes.

}, keywords = {covalent-organic framework, hollow fiber, interfacial polymerization, organic solvent nanofiltration, selective COF membrane}, issn = {1944-8244}, doi = {10.1021/acsami.4c00305}, author = {Kunjattu, Shebeeb H. and Thorat, Nitin M. and Gawas, Saroj and Kharul, Ulhas K.} }