02012nas a2200229   4500008004100000022001400041245009400055210006900149260010600218300001400324490000700338520114600345653001701491653002101508653002401529653001601553100002201569700002201591700001901613700002301632856012701655       2005                        eng d  a0014-305700aBenzoylation of polyphenylene oxide: characterization and gas permeability investigations0 aBenzoylation of polyphenylene oxide characterization and gas per  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcOCT  a2461-24710 v413 a<p>Benzoylation of polyphenylene oxide (PPO) was carried out with aromatic acid chlorides bearing specific groups at para-position (H methyl, Br, Cl and nitro), which differ in their polarity and bulk. The reaction conditions were optimized individually to get the high degree of substitution. These materials were characterized for thermal as well as other physical properties that are known to affect the gas permeation. In a series investigated, the nitrobenzoyl substitution on PPO resulted in the highest increase in glass transition temperature and the lowest thermal stability. An estimation of the packing density parameters-fractional free volume by density measurement and the d-spacing by X-ray diffraction analysis showed an increase in the packing density. The gas permeability was found to decrease in all the cases of benzoylation. The helium and oxygen based selectivities were increased, while CO2 based selectivities were decreased. The unusual trend observed in the gas permeation properties is explained on the basis of nature of substituent and the degree of substitution. (c) 2005 Elsevier Ltd. All rights reserved.</p>10abenzoylation10aGas permeability10apolyphenylene oxide10aselectivity1 aBhole, Yogesh, S.1 aKharul, Ulhas, K.1 aSomani, S., P.1 aKumbharkar, S., C.  uhttps://library.ncl.res.in/content/benzoylation-polyphenylene-oxide-characterization-and-gas-permeability-investigations-002617nas a2200217   4500008004100000022001400041245018200055210006900237260009900306300001400405490000700419520168000426653002102106653002202127653002902149100002302178700002302201700002102224700002202245856013202267       2009                        eng d  a0032-386100aVariation in acid moiety of polybenzimidazoles: investigation of physico-chemical properties towards their applicability as proton exchange and gas separation membrane materials0 aVariation in acid moiety of polybenzimidazoles investigation of   aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcMAR  a1403-14130 v503 a<p>A series of polybenzimidazoles (PBIs) were prepared from 3,3'-diaminobenzidine (DAB) and substituted aromatic dicarboxylic acids. Effects of added polarity, bulk and isomerism in the dicarboxylic acid moiety on the properties of formed aromatic polybenzimidazoles were investigated. Solution polycondensation procedure was optimized for individual case of PBI synthesis in order to obtain inherent viscosity of &gt;= 1 dL/g. Analysis of physical properties, water uptake, acid doping (H(3)PO(4) and H(2)SO(4)) and gas permeability was performed. All these PBIs exhibited high thermal stability, good solvent solubility and amorphous nature. The uptake of H(3)PO(4) varied from 9 to 20.1 moles per repeat unit (mol/RU), H(2)SO(4) uptake varied from 3.39 to 3.81 mol/RU, while water uptake varied from 1.8 to 3.6 mol/RU of PBI. The dibromoterephthalic acid and tert-butylisophthalic acid based PBI showed the highest H(3)PO(4) uptake in the series, while tert-butylisophthalic acid based PBI exhibited the highest water uptake. Acid uptake was correlated with swelling of the PBI matrix, while density estimation of H(3)PO(4)-doped PBI by He gas expansion method could be correlated to the physical state of PBI. 5-tert-Butylisophthalic acid and 4,4'-(hexafluoroisopropylidene)bis(benzoic acid) based PBI exhibited higher H(2) and O(2) permeability than other PBIs. The ideal gas selectivity for O(2)/H(2) was considerably higher for most of the PBIs than conventional gas separation membrane materials. These analyses suggested that some of these PBIs have a potential to be used as a PEM or gas separation membrane material. (C) 2009 Elsevier Ltd. All rights reserved.</p>10aGas permeability10aPolybenzimidazole10aProton exchange membrane1 aKumbharkar, S., C.1 aIslam, Md., Nazrul1 aPotrekar, R., A.1 aKharul, Ulhas, K.  uhttps://library.ncl.res.in/content/variation-acid-moiety-polybenzimidazoles-investigation-physico-chemical-properties-towards-002538nas a2200229   4500008004100000022001400041245014600055210006900201260000900270300001200279490000700291520170500298653002102003653002802024653001502052653001902067100002102086700001902107700002202126700002802148856013202176       2018                        eng d  a0887-624X00aIntrinsically microporous polyimides containing spirobisindane and phenazine units: synthesis, characterization and gas permeation properties0 aIntrinsically microporous polyimides containing spirobisindane a  cAPR   a766-7750 v563 aA new diamine containing spirobisindane and phenazine units, namely, 3,3,3,3-tetramethyl-2,2,3,3-tetrahydro-1,1-spirobi[cyclopenta[b]phen azine]-7,7-diamine (TTSBIDA) was synthesized starting from commercially available 5,5,6,6-tetrahydroxy-3,3,3,3-tetramethyl-1,1-spirobisindane (TTSBI). TTSBI was oxidized to 3,3,3,3-tetramethyl-2,2,3,3-tetrahydro-1,1-spirobi[indene]-5,5,6,6-tet raone (TTSBIQ) which was subsequently condensed with 4-nitro-1,2-phenylenediamine to obtain 3,3,3,3-tetramethyl-7,7-dinitro-2,2,3,3-tetrahydro-1,1-spirobi[cyclope nta[b]phenazine] (TTSBIDN). TTSBIDN was converted into TTSBIDA by reduction of the nitro groups using hydrazine hydrate in the presence of Pd/C as the catalyst. A series of new polyimides of intrinsic microporosity (PIM-PIs) were synthesized by polycondensation of TTSBIDA with commercially available aromatic dianhydrides. PIM-PIs exhibited amorphous nature, high thermal stability (T-10&gt;480 degrees C) and intrinsic microporosity (BET surface area=59-289 m(2)/g). The gas permeation characteristics of films of selected PIM-PIs were evaluated and they exhibited appreciable gas permeability as well as high selectivity. The CO2 and O-2 permeability of PIM-PIs were in the range 185.4-39.2 and 30.6-6.2 Barrer, respectively. Notably, polyimide derived from TTSBIDA and 4,4-(hexafluoroisopropylidene)diphthalic anhydride (PIM-PI-6FDA) exhibited high CO2 and O-2 permeability of 185.4 and 30.6 Barrer with CO2/CH4 and O-2/N-2 selectivity of 43.1 and 5.1, respectively. The data of PIM-PI-6FDA for CO2/CH4 and O-2/N-2 gas pairs were located near Robeson upper bound. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 766-77510aGas permeability10aintrinsic microporosity10apolyimides10aspirobisindane1 aShrimant, Bharat1 aDangat, Yuvraj1 aKharul, Ulhas, K.1 aWadgaonkar, Prakash, P.  uhttps://library.ncl.res.in/content/intrinsically-microporous-polyimides-containing-spirobisindane-and-phenazine-units-synthesis