02183nas a2200253 4500008004100000022001400041245014700055210006900202260006800271300001400339490000700353520122700360653002801587653001401615653001901629653001701648653001701665653001601682653003301698100002301731700002501754700002201779856012801801 2007 eng d a0887-626600aEffect of substituent polarity, bulk, and substitution site toward enhancing gas permeation in dibromohexafluorobisphenol-A based polyarylates0 aEffect of substituent polarity bulk and substitution site toward a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcDEC a3156-31680 v453 a

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'-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.

10aasymmetric substitution10aDiffusion10aGas permeation10agas sorption10apolyarylates10aselectivity10astructure-property relations1 aIshole, Yogesh, S.1 aKaradkar, Prasad, R.1 aKharul, Ulhas, K. uhttps://library.ncl.res.in/content/effect-substituent-polarity-bulk-and-substitution-site-toward-enhancing-gas-permeation-002232nas a2200253 4500008004100000022001400041245011000055210006900165260006800234300001400302490000800316520130500324653001901629653001401648653001501662653001601677653003301693100002701726700002501753700002201778700002401800700002601824856012801850 2008 eng d a0021-899500aSynthesis, characterization, and gas permeability of aromatic polyimides containing pendant phenoxy group0 aSynthesis characterization and gas permeability of aromatic poly a111 RIVER ST, HOBOKEN, NJ 07030 USAbJOHN WILEY & SONS INCcJUN a3881-38890 v1083 a

A diamine containing a pendant phenoxy group, 1-phenoxy-2,4-diaminobenzene, was synthesized and condensed with different aromatic dianhydrides [4,4'-oxydiphthalic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 3,3',4,4-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-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'-oxydiphthalic dianhydride and 4,4'-(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.

10aGas permeation10amembranes10apolyimides10aselectivity10astructure-property relations1 aKothawade, Sandeep, S.1 aKulkarni, Mahesh, P.1 aKharul, Ulhas, K.1 aPatil, Anandrao, S.1 aVernekar, Subhash, P. uhttps://library.ncl.res.in/content/synthesis-characterization-and-gas-permeability-aromatic-polyimides-containing-pendant-002571nas a2200241 4500008004100000022001400041245012400055210006900179260000900248300001000257490000700267520172200274653001501996653001902011653002802030653001402058653003302072100002102105700002602126700002202152700002802174856012702202 2018 eng d a0887-624X00aSynthesis, characterization, and gas permeation properties of adamantane-containing polymers of intrinsic microporosity0 aSynthesis characterization and gas permeation properties of adam cJAN  a16-240 v563 a

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.

10aadamantane10aGas permeation10aintrinsic microporosity10amembranes10astructure-property relations1 aShrimant, Bharat1 aShaligram, Sayali, V.1 aKharul, Ulhas, K.1 aWadgaonkar, Prakash, P. uhttps://library.ncl.res.in/content/synthesis-characterization-and-gas-permeation-properties-adamantane-containing-polymers