Thermally rearranged polybenzoxazoles made from poly(ortho-hydroxyamide)s. Characterization and evaluation as gas separation membranes

Díez, Blanca; Cuadrado, Purificación; Marcos‐Fernández, Ángel; Campa, José G. de la; Tena, Alberto; Prádanos, Pedro; Palacio, Laura; Lee, Young Moo; Álvarez, Celedonio M.; Lozano, Ángel E.; Hernández, Antonio

doi:10.1016/j.reactfunctpolym.2018.03.013

Cited by 32 publications

(19 citation statements)

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“…In all cases, two common regions of weight loss for the membranes were observed. The first step (in the range from 200 to 400 °C) of weight loss was associated with the thermal rearrangement from polymer matrix moieties to benzoxazole ones, whereas the second step (well above 400 °C) was associated with thermal degradation [ 18 , 41 , 42 , 43 ]. Note that polymer degradation occurred above 450 °C in the case of MMMs, which ruled out any potential degradation of the PPNs due to its high thermal resistance (PPN-2 degradation occurred around 490 °C under a N 2 atmosphere) [ 24 ].…”

Section: Resultsmentioning

confidence: 99%

Gas Separation by Mixed Matrix Membranes with Porous Organic Polymer Inclusions within o-Hydroxypolyamides Containing m-Terphenyl Moieties

et al. 2021

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A hydroxypolyamide (HPA) manufactured from 2,2-bis(3-amino-4-hydroxy phenyl)-hexafluoropropane (APAF) diamine and 5′-terbutyl-m-terphenyl-4,4′′-dicarboxylic acid chloride (tBTpCl), and a copolyimide produced by stochiometric copolymerization of APAF and 4,4′-(hexafluoroisopropylidene) diamine (6FpDA), using the same diacid chloride, were obtained and used as polymeric matrixes in mixed matrix membranes (MMMs) loaded with 20% (w/w) of two porous polymer networks (triptycene-isatin, PPN-1, and triptycene-trifluoroacetophenone, PPN-2). These MMMs, and also the thermally rearranged membranes (TR-MMMs) that underwent a thermal treatment process to convert the o-hydroxypolyamide moieties to polybenzoxazole ones, were characterized, and their gas separation properties evaluated for H2, N2, O2, CH4, and CO2. Both TR process and the addition of PPN increased permeability with minor decreases in selectivity for all gases tested. Excellent results were obtained, in terms of the permeability versus selectivity compromise, for H2/CH4 and H2/N2 separations with membranes approaching the 2008 Robeson’s trade-off line. The best gas separation properties were obtained when PPN-2 was used. Finally, gas permeation was characterized in terms of chain intersegmental distance and fraction of free volume of the membrane along with the kinetic diameters of the permeated gases. The intersegmental distance increased after TR and/or the addition of PPN-2. Permeability followed an exponential dependence with free volume and a quadratic function of the kinetic diameter of the gas.

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Section: Resultsmentioning

confidence: 99%

Gas Separation by Mixed Matrix Membranes with Porous Organic Polymer Inclusions within o-Hydroxypolyamides Containing m-Terphenyl Moieties

et al. 2021

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“…The 6FCl-APAF poly(o-hydroxyamide) has been already synthesized by us [15] but it will be described below because some modifications were introduced.…”

Section: Synthesis Of the Poly(hydroxyamide)(hpa) 6fcl-apaf As Tr Precursormentioning

confidence: 99%

“…It is worth mentioning that there are significant variations in permeability and selectivity for the membranes without thermal rearrangement that could be attributed to the presence of variable small amounts of solvent retained within both the polymeric matrix [15] and the PPN filler. In Fig.…”

Section: Gas Separation Propertiesmentioning

confidence: 99%

“…Although this technology is already available at commercial scale, there is still need for further research in materials science in order to manufacture membranes with an optimum balance between CO2 permeability and CO2/CH4 selectivity [14]. Indeed, membranebased CO2 separation has gained a significant market share from 2012 to 2016 based on the recent advances on polymer science [15]. In this sense, mixed matrix membranes (MMMs) and polymers made by via thermal rearrangement (TR) exhibit a high free volume fraction (FFV) along with a high permeability compared to commercial cellulose acetate [16,17].…”

Section: Introductionmentioning

confidence: 99%

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Enhancement of CO2/CH4 permselectivity via thermal rearrangement of mixed matrix membranes made from an o-hydroxy polyamide with an optimal load of a porous polymer network

Soto

Aguilar‐Lugo

Rodríguez

et al. 2020

Separation and Purification Technology

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Mixed matrix membranes, MMMs, consisting of variable loads of a porous polymer network, PPN, within an o-hydroxipolyamide, HPA (6FCl-APAF, made from the reaction between 2,2-bis[4-chlorocarbonylphenyl)hexafluoropropane, 6FCl, and 2,2bis(3-amino-4-hydroxyphenyl)hexafluoropropane, APAF), have been thermally treated to induce the rearrangement of HPA to a polybenzoxazole (β-TR-PBO). HPA is 6FCl-APAF was loaded with a PPN synthetized, by us, by combining triptycene (TRP) and trifluoroacetophenone (TFAP). Mechanical, thermal and morphological properties of the membranes have been determined.CO2/CH4 selectivity of MMMs decreased slightly both when the PPN load was augmented and when thermal rearrangement took place. The changes in selectivity can be attributed mostly to solubility effects for β-TR-MMMs and to diffusive effects for the © YYYY Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 MMM from neat HPA. CO2 and CH4 permeabilities increased to the 2008 Robeson´s upper bond for an optimal 30 % PPN load both before and after thermal rearrangement.These relatively good permselectivities are explained in terms of compaction, rigidity, fractional free volumes and filling-matrix interactions.

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“…Similar polymers were also obtained at 375 °C by Díez et al . using a TCD process . The results of the two studies were similar and the polymers formed were found to be insoluble.…”

Section: Macromolecular Tr Chemistrymentioning

confidence: 73%

Understanding structure and composition of thermally rearranged polymers based on small‐molecule chemistry: a perspective

Murugesan¹,

Sivaram

2019

Polymer International

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We provide a critical perspective of the burgeoning literature on microporous polymers prepared using thermal rearrangement (TR) processes based on the learning derived from analogous chemistry involving small‐molecular‐weight compounds. TR polymers have shown interesting permeability–selectivity relationships in gas separation and, thus, have generated wide interest as potential membrane materials for industrial applications. The intractable nature of the products obtained by TR processes has precluded rigorous structural elucidation of the polymers. Based on small‐molecule chemistry, we conclude that structures are likely to be more complex than generally depicted in the published literature. Interestingly, a simpler chemistry, namely thermal dehydrocyclization (TCD), leads to products identical to those derived from TR, but at significantly lower temperatures. However, TCD chemistry does not involve a skeletal rearrangement of the kind purported in TR during the conversion of imide to oxazole ring resulting in spatially confined heterocyclic ring polymers. Yet, they show similar fractional free‐volume elements as exhibited by TR polymers. This is intriguing and points to a need for more careful examination of the factors responsible for microporosity in such materials. TR chemistry as currently practiced appears limited to only benzoxazole‐type structures. The ability to precisely control and reproducibly produce materials with well‐defined structure and properties will be a key to large‐scale manufacture and industrial applications of such materials. Seen from this perspective, TR processes leave much to be desired and further improvements are clearly warranted. © 2019 Society of Chemical Industry

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Thermally rearranged polybenzoxazoles made from poly(ortho-hydroxyamide)s. Characterization and evaluation as gas separation membranes

Cited by 32 publications

References 38 publications

Gas Separation by Mixed Matrix Membranes with Porous Organic Polymer Inclusions within o-Hydroxypolyamides Containing m-Terphenyl Moieties

Gas Separation by Mixed Matrix Membranes with Porous Organic Polymer Inclusions within o-Hydroxypolyamides Containing m-Terphenyl Moieties

Enhancement of CO2/CH4 permselectivity via thermal rearrangement of mixed matrix membranes made from an o-hydroxy polyamide with an optimal load of a porous polymer network

Understanding structure and composition of thermally rearranged polymers based on small‐molecule chemistry: a perspective

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