Browsing by Author "Cruz, Yennier"

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    A semi-rigid co-poly(imide) derived from an isomeric mixture of monomers. Assessing gas transport properties in self-standing polymer membrane
    (2024) Cruz, Yennier; Rodriguez, Ary; Rodriguez-Gonzalez, Fidel E.; V. Velazquez-Tundidor, Maria; Niebla, Vladimir; Aguilar-Vega, Manuel; Sulub-Sulub, Rita; Coll, Deysma; Terraza, Claudio A.; Tundidor-Camba, Alain
    Chemical structure and morphology of polymers are directly related with the membrane separation performance. Poly(imide)s (PIs) are the most widely used polymers in the preparation of membranes for gas separation applications; thus, research on the structural design of polymers is of great interest to develop new membranes. In the present work, we reported the synthesis, characterization, and measurement of the gas transport properties of a new co-poly(imide)s (PI-D2a-D2b-6FDA) prepared from a mixture of isomeric diamines. The co-poly(imide) synthetic route involved several steps, starting by a bromination reaction, followed by a double nucleophilic aromatic substitution giving an isomeric mixture of precursors, which suffered a Suzuki-Miyaura C-C crosscoupling reaction followed by the reduction of nitro groups to give two new isomeric diamines. Finally, diamines simultaneously reacted with the dianhydride 6FDA to obtain PI-D2a-D2b-6FDA. The co-poly(imide) had a Mn of 47.7 kDa and a Mw of 74.0 kDa with a PDI of 1.6. The sample exhibited a 10% weight loss at 540 degrees C, Tg of 280 degrees C, BET surface area of 110 m2 g-1, and wide-angle X-ray diffraction (WAXD) interchain d -spacing at 9.5 & Aring; and 6.3 & Aring;. Tensile strength, elongation at break and Young's modulus were 109.6 MPa, 6.66% and 2.18 GPa, respectively. co-Poly(imide) was soluble in various polar aprotic organic solvents such as DMSO, NMP, DMF, DMAc, THF, and chloroform, forming a self -standing dense film whose gas transport properties were measured. Pure gas permeability coefficients for H2, CO2, O2, N2, and CH4, were 47.28, 24.04, 4.35, 1.02, and 0.76 (Barrer), respectively, which follows a decreasing order by the increasing kinetic diameters of the respective gases. Ideal gas selectivities H2/N2, O2/N2, CO2/CH4, and CO2/N2 were 46.4, 4.3, 31.6, and 23.6, respectively. These gas transport properties were compared with the commercial polymer Matrimid (R), showing higher gas permeability coefficients than Matrimid (R).
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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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    Polyimides Containing Biphenyl and Troger's Base Units for Gas Separation Membranes
    (2024) Rodriguez, Ary; Tundidor, Maria Victoria Velazquez; Cruz, Yennier; Rodriguez-Gonzalez, Fidel Ernesto; Aguilar-Vega, Manuel J.; Sulub-Sulub, Rita; Ravula, Sudhir; Bara, Jason E.; Terraza, Claudio A.; Tundidor-Camba, Alain
    Two diamine monomers containing biphenyl and Tr & ouml;ger's base units were synthesized, and each diamine that differed by the presence of two -CH3 groups was reacted with commercially 4,4 '-hexafluoroisopropylidene diphthalic anhydride (6FDA) for obtaining two polyimides of intrinsic microporosity (PIM-TB-PI-1 and PIM-TB-PI-2) with structural elements that ensured the formation of contorted and semirigid chains. Both PIM-PIs were soluble in polar aprotic solvents, including tetrahydrofuran and chloroform, showing high thermal stability (T-d > 500 degrees C) and high glass transition temperatures (T-g > 300 degrees C). The surface area and the distance between polymer chains were determined by using N-2 adsorption/desorption and wide-angle X-ray diffraction (XRD) techniques, respectively. PIM-TB-PI-1 showed a surface area of 81 m(2) g(-1) and d-spacing of 5.9 & Aring;, while PIM-TB-PI-2 had slightly higher values (SA = 109 m(2) g(-1) and d-spacing = 6.3 & Aring;). PIM-TB-PI-1 and PIM-TB-PI-2 form dense films that exhibited pure gas permeability coefficients that are 1 order of magnitude higher than Matrimid while they present lower perm-selectivities than the former. This result is related to chain rigidity in PIM-TB-PIs that maintains a distribution of microvoids that are large enough for these gases to diffuse through the interconnected free volume, and the TB units in the main chain of both polymers increase steric hindrance for gas permeability and diffusion. The higher diffusion coefficients of PIM-TB-PI-2, as compared to PIM-TB-PI-1 are related to the presence of -CH3 groups near the imide group, preventing an efficient packing of the polymer chains.