Polymer materials derived from the SEAr reaction for gas separation applications

Producción CientíficaA set of linear polymers were synthesized utilizing an electrophilic aromatic substitution reaction (SEAr) between biphenyl and ketone containing electron-withdrawing groups (isatin, IS; N-methylisatin, MeIS; and 4,5-diazafluoren-9-one, DF). Optimization of the polycondensation reaction was made to obtain high molecular weight products when using DF, which has not previously been used for linear polymer synthesis. Due to the absence of chemically labile units, these polymers exhibited excellent chemical and thermal stability. Linear SEAr polymers were blended with porous polymer networks derived from IS and MeIS, and both neat/mixed materials were tested as membranes for gas separation. The gas separation properties of both pristine polymers and mixed matrix membranes were good, showing some polymer membrane CO2 permeability values higher than 200 barrer

Gas separation membranes obtained by partial pyrolysis of polyimides exhibiting polyethylene oxide moieties

Aromatic copolyimides (PIx) and aromatic-aliphatic copolyimides (PIxEOy) were synthesized by reacting 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) with mixtures obtained from 2,2′-bis(4-aminophenyl)hexafluoropropane (6FpDA), 5-diaminobenzoic acid (DABA) and Jeffamine ED-2003 (PEO). The selective thermal removal of PEO from PIxEOy yielded membranes with high thermal stability and good mechanical properties. The presence of carboxylic groups minimized the shrinkage during the cross-linking process. The membranes containing 10 mol% DABA exhibited good O2/N2 and CO2/CH4 separation performance, and resistance to CO2 plasticization. PIx/PIxEOy blends containing less than 10 wt% PEO were prepared. The CO2/CH4 selectivity/permeability balance of cross-linked membranes largely exceeded that of PIx. The results highlight a possible strategy for using analogous cross-linkable polymers exhibiting ethylene oxide moieties as mere additive to prepare high free volume polyimide's membranes, exhibiting enhanced separation properties and high resistance to plasticization.This work was supported by the Spanish Government (AEI) through projects PID2019-109403RB-C21, PID2019-109403RB-C22 and PID2020-118547 GB-I00, and by the Regional Government of Castilla y León and the EU-FEDER program (CLU2017-09, UIC082, VA088G19 and VA224P20). M.G. acknowledges support of this work from the University of Oklahoma (VPR OfficePeer reviewe

Alilsilanos como herramientas eficaces en la síntesis de tetrahidropiranos

En este proyecto se han estudiado las posibilidades sintéticas de los compuestos organosilícicos como intermedios en la síntesis de éteres cíclicos de seis eslabones. Estos éteres cíclicos tienen gran importancia ya que aparecen frecuentemente en productos naturales con interesantes propiedades biológicas. Las ciclaciones ocurren con total regioselectividad debido a la estabilización de carbocationes en β al silicio. Asimismo, la ciclación transcurre con total estereoselectividad, obteniéndose un único diastereoisómero en el proceso.Grado en Químic

Síntesis de tetrahidropiranos por ciclación ácido-catalizada de alilsilil alcoholes

El presente proyecto tiene como objetivo desarrollar un método de síntesis eficaz de tetrahidropiranos por ciclación intramolecular de alquenil alcoholes sililados. Se ha observado que las ciclaciones catalizadas por ácidos transcurren con gran rendimiento y elevada estereoselectividad. Estos oxaciclos tienen gran interés pues aparecen con frecuencia en la estructura de muchos productos naturales con importantes propiedades biológicas.Departamento de Química OrgánicaMáster en Técnicas Avanzadas en Química. Análisis y Control de Calidad Químico

Mixed matrix membranes using porous organic polymers (POPs) - influence of textural properties on CO2/CH4 separation

Mixed matrix membranes (MMMs) provide the opportunity to test new porous materials in challenging applications. A series of low-cost porous organic polymer (POPs) networks, possessing tunable porosity and high CO2 uptake, has been obtained by aromatic electrophilic substitution reactions of biphenyl, 9,10-dihydro-9,10-dimethyl-9,10-ethanoanthracene (DMDHA), triptycene and 1,3,5-triphenylbenzene (135TPB) with dimethoxymethane (DMM). These materials have been characterized by FTIR, 13C NMR, WAXD, TGA, SEM, and CO2 uptake. Finally, different loadings of these POPs have been introduced into Matrimid, Pebax, and chitosan:polyvinyl alcohol blends as polymeric matrices to prepare MMMs. The CO2/CH4 separation performance of these MMMs has been evaluated by single and mixed gas permeation experiments at 4 bar and room temperature. The effect of the porosity of the porous fillers on the membrane separation behavior and the compatibility between them and the different polymer matrices on membrane design and fabrication has been studied by Maxwell model equations as a function of the gas permeability of the pure polymers, porosity, and loading of the fillers in the MMMs. Although the gas transport properties showed an increasing deviation from ideal Maxwell equation prediction with increasing porosity of the POP fillers and increasing hydrophilicity of the polymer matrices, the behavior of biopolymer-based CS:PVA MMMs approached that of Pebax-based MMMs, giving scope to not only new filler materials but also sustainable polymer choices to find a place in membrane technology.This research was funded by IVACE program, Generalitat Valenciana, at the University of Cantabria, grant number PRO-81. THE APC was funded by the University of Cantabria. Also, this research was funded by Spain’s Agencia Estatal de Investigación (AEI) (Projects: PID2019-109403RB-C22 (AEI/FEDER, UE), and PID2019-109403RB-C21 (AEI/FEDER, UE))

Isomeric Aromatic Polyimides Containing Biphenyl Moieties for Gas Separation Applications

An optimized synthesis of the monomer 2,2′3,3′-biphenyltetracarboxylic dianhydride, iBPDA, was performed to obtain high molecular weight polymers. This monomer has a contorted structure that produces a non-linear shape, hindering the packing of the polymer chain. Aromatic polyimides of high molecular weight were obtained by reaction with the commercial diamine 2,2-bis(4-aminophenyl) hexafluoropropane, 6FpDA, which is a very common monomer in gas separation applications. This diamine has hexafluoroisopropylidine groups which introduce rigidity in the chains, hindering efficient packing. The thermal treatment of the polymers processed as dense membranes had two targets: on the one hand, to achieve the complete elimination of the solvent used, which could remain occluded in the polymeric matrix, and on the other hand to ensure the complete cycloimidization of the polymer. A thermal treatment exceeding the glass transition temperature was performed to ensure the maximum degree of imidization at 350 °C. The good mechanical properties of these materials allow for their use in high-pressure gas purification applications. Moreover, models of the polymers exhibited an Arrhenius-like behavior characteristic of secondary relaxations, normally associated with local motions of the molecular chain. The gas productivity of these membranes was high.This research was funded by the Spanish Government (AEI) through projects PID2019-109403RB-C21 and PID2019-109403RB-C22, and by Spain’s Regional Government of Castilla y León and the EU-FEDER program (CLU2017-09, UIC082 and VA088G19)Peer reviewe