Browsing by Author "Comesana-Gandara, Bibiana"

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    New polyimides containing methyl benzamidobenzoate or dimethyl benzamidoisophthalate as bulky pendant groups. Effects on solubility, thermal and gas transport properties
    (2022) Terraza, Claudio A.; Cruz, Yennier; Rodriguez, Ary; Victoria Velazquez-Tundidor, Maria; Hauyon, Rene A.; Rodriguez-Gonzalez, Fidel E.; Niebla, Vladimir; Aguilar-Vega, Manuel; Sulub-Sulub, Rita; Coll, Deysma; Ortiz, Pablo A.; Perez, Yasmin P.; Comesana-Gandara, Bibiana; Tundidor-Camba, Alain
    This work reports the synthesis of six new polyimides obtained by the reaction of two novel diamine monomers: methyl 4-(3,5-diaminobenzamido)benzoate and dimethyl 5-(3,5-diaminobenzamido)isophthalate, bearing one or two methyl ester groups in their phenyl rings, respectively, with three known dianhydrides, 4,4 '-(hexafluoroisopropylidene) diphatalic anhydride (6FDA), 4,4 '-(dimethylsilanediyl) dipthalic anhydride (SiDA) and 4,4 '-oxydiphthalic anhydride (ODPA). The polyimides were synthesized using the "two-step" method, which first involves forming a poly(amic acid) precursor that is subsequently cyclodehydrated to form the imide linkage. The yields were higher than 95% in all cases, and the structural characterization was performed by spectroscopic techniques like FT-IR, H-1, C-13, and Si-29 NMR. In addition, the effect on the solubility in common organic solvents and thermal and gas transport properties of these polyimides were studied as a function of the nature of the respective side group and the dianhydride used.
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    Polymers of intrinsic microporosity containing aryl-phthalimide moieties: synthesis, modeling, and membrane gas transport properties
    (2023) Rodriguez-Gonzalez, Fidel E.; Soto, Cenit; Palacio, Laura; Montero-Alejo, Ana L.; Escalona, Nestor; Schott, Eduardo; Comesana-Gandara, Bibiana; Terraza, Claudio A.; Tundidor-Camba, Alain
    High-performance polymers for membrane gas separation require the careful design of the structure-porous relationship. In this work, five phthalimide-based polymers of intrinsic microporosity (PIMs) were obtained via the double nucleophilic aromatic substitution with the commercially available 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethylspirobisindane (TTSBI) monomer. The phthalimide monomers were synthesized considering different sizes and positions of the alkyl-substituents to evaluate their influence on the physical properties of the polymers and their potential use as gas separation membranes. Four polymers were soluble in the low-boiling solvents chloroform and tetrahydrofuran, facilitating the casting of self-standing films to evaluate their gas separation properties. The thermally stable membranes showed 5% weight lost between 537 ? and 549 ?. As powders, these four polymers showed apparent BET surface areas ranging from 434 to 661 m(2) g(-1). The experimental BET surface areas correlated with those obtained by molecular simulation models of the synthesized polymers. A linear function is proposed as a tool to predict, with a known uncertainty, the surface area values of this type of polymer from the corresponding computational models. As a trend, increasing the volume of the ortho-substituent in the aryl-phthalimide group increases the permeability of the membranes, reaching generally better performances than Matrimid (R) and close to those of PIM-1, considering their place on the Robeson diagrams of the O-2/N-2, CO2/CH4 and CO2/N-2 gas pairs. Aging studies between 63 and 122 days showed a decrease in permeability, accompanied by the typical increase in selectivity that tends to move the data parallel to the upper Robeson limits.