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Open AccessArticle

Gas Permeation Properties of Soluble Aromatic Polyimides Based on 4-Fluoro-4,4'-Diaminotriphenylmethane

Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas Norte 152, 07730 México, Mexico
Universidad Iberoamericana, Departamento de Ingenierías. Prol. Paseo de la Reforma No. 880, Col. Lomas de Santa Fe, C. P. 01219 México, Mexico
Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, 14 sur y San Claudio, Ciudad Universitaria, 72592 Puebla, Pue., Mexico
Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito exterior s/n, Cuidad Universitaria, 70360 México, Mexico
Authors to whom correspondence should be addressed.
Academic Editor: Christof Schneider
Materials 2015, 8(4), 1951-1965;
Received: 26 January 2015 / Revised: 26 March 2015 / Accepted: 9 April 2015 / Published: 21 April 2015
(This article belongs to the Section Energy Materials)
A series of new organic polyimides were synthesized from 4-fluoro-4'4"-diaminotriphenylmethane and four different aromatic dianhydrides through a one-step, high-temperature, direct polycondensation in m-cresol at 180–200 °C, resulting in the formation of high-molecular-weight polyimides (inherent viscosities ~ 1.0–1.3 dL/g). All the resulting polyimides exhibited good thermal stability with initial decomposition temperatures above 434 °C, glass-transition temperatures between 285 and 316 °C, and good solubility in polar aprotic solvents. Wide-angle X-ray scattering data indicated that the polyimides were amorphous. Dense membranes were prepared by solution casting and solvent evaporation to evaluate their gas transport properties (permeability, diffusivity, and solubility coefficients) toward pure hydrogen, helium, oxygen, nitrogen, methane, and carbon dioxide gases. In general, the gas permeability was increased as both the fractional free volume and d-spacing were also increased. A good combination of permeability and selectivity was promoted efficiently by the bulky hexafluoroisopropylidene and 4-fluoro-phenyl groups introduced into the polyimides. The results indicate that the gas transport properties of these films depend on both the structure of the anhydride moiety, which controls the intrinsic intramolecular rigidity, and the 4-fluoro-phenyl pendant group, which disrupts the intermolecular packing. View Full-Text
Keywords: polyimides; 4-fluoro-4'-4"-diaminotriphenylmethane; gas separation membranes polyimides; 4-fluoro-4'-4"-diaminotriphenylmethane; gas separation membranes
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Guzmán-Lucero, D.; Palomeque-Santiago, J.F.; Camacho-Zúñiga, C.; Ruiz-Treviño, F.A.; Guzmán, J.; Galicia-Aguilar, A.; Aguilar-Lugo, C. Gas Permeation Properties of Soluble Aromatic Polyimides Based on 4-Fluoro-4,4'-Diaminotriphenylmethane. Materials 2015, 8, 1951-1965.

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