Cristina Álvarez

• Spanish National Research Council

Microporous glassy polymer membranes suffer from physical aging, which adversely affects their performance in the short time frame. We show that the aging propensity of a model microporous polymer, poly(1-trimethylsilyl-1-propyne) (PTMSP), can be effectively mitigated by blending with as little as 5 wt % porous polymer network (PPN) composed of tri...

A series of polyimides (PIs) was synthesized from 6FDA and two o-OH substituted diamines having bulky pendant phenyl, Ph, and trifluoromethyl, CF3, groups as precursors for thermally rearranged polybenzoxazole, TR-PBO, membranes. One diamine had two pendant Ph substituents; in the other, the substituents were Ph and CF3. Applying azeotropic and che...

Despite exhibiting excellent thermal/chemical stability, mechanical robustness, and easy processability, which makes them attractive candidates for gas separation applications, aromatic polyimides are susceptible to plasticization. This study proposes an effective approach to suppress CO2-induced plasticization in a high fractional free volume (FFV...

A new set of microporous organic polymers (POPs) containing diphosphine derivatives synthesized by knitting via Friedel–Crafts has been attained. These amorphous three-dimensional materials have been prepared by utilizing diphosphines, 1,3,5-triphenylbenzene, and biphenyl as nucleophile aromatic groups, dimethoxymethane as the electrophilic linker,...

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...

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 commer...

By employing a variation of the polyamidation method using in situ silylated diamines and acid chlorides, it was possible to obtain a rod-type polyamide: poly(p-phenylene terephthalamide) (PPTA, a polymer used in the high-value-added material Kevlar), with a molecular weight much higher than that obtained with the classical and industrial polyamida...

By employing a variation of the polyamidation method using in situ silylated diamines and acid chlorides, it has been possible to obtain a rod-type polyamide: poly(p-phenylene terephthalamide) (PPTA, a polymer used in the high value-added material Kevlar), with a molecular weight much higher than that obtained with the classical, and industrial, po...

A set of aromatic copolyimides was obtained by reaction of 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), and mixtures of the diamines 1,4-bis(4-amino-2-trifluoromethylphenoxy)-2,5-di-tert-butylbenzene (CF3TBAPB) and 3,5-diamino benzoic acid (DABA). These polymers were characterized and compared with the homopolymer derived from 6FDA...

A 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 D...

A set of aromatic copolyimides was obtained by reaction of 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), and mixtures of the diamines 1,4-bis(4-amino-2-trifluoromethylphenoxy)-2,5-di-tert-butylbenzene (CF3TBAPB) and 3,5-diamino benzoic acid (DABA). These polymers were characterized and compared with the homopolymer derived from 6FDA...

Copoly(o-hydroxyamide)s (HPA) and copoly(o-hydroxyamide-amide)s (PAA) have been synthesized to be used as continuous phases in mixed matrix membranes (MMMs). These polymeric matrices were blended with different loads (15 and 30 wt.%) of a relatively highly microporous porous polymer network (PPN). SEM images of the manufactured MMMs exhibited good...

A new set of catalytic materials having a pyrrolidine moiety confined in microporous organic polymer networks (POPs) has been attained. These catalytic polymers have been prepared by a straightforward synthesis starting from microporous polymer networks made from isatin (or a mixture of isatin and trifluoroacetophenone) and 1,3,5-triphenylbenzene....

Mixed matrix membranes (MMMs), derived from three aromatic polyimides (PIs), and an affordable porous organic polymer (POP) having basic bipyridine moieties were prepared. Matrimid and two fluorinated polyimides, which were derived from 4,4′-(hexafluoroisopropylidene)diphthalic anhydride and 2,2′-bis(4-aminophenyl)hexafluoropropane (6F6F) or 2,4,6-...

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 yie...

Mixed matrix membranes (MMMs) have been obtained by blending an aromatic ortho-hydroxypolyimide (PIOH) or an ortho-acetylpolyimide (PIOAc) with different loading amounts (15 and 30 wt %) of a microporous polymer network (PPN), which was obtained from the reaction of triptycene and isatin. The excellent thermal resistance of the PPN (above 500 °C) a...

A new generation of confined palladium(II) catalysts covalently attached inside of porous organic polymers (POPs) has been attained. The synthetic approach employed was straightforward, and there was no prerequisite for making any modification of the precursor polymer. First, POP-based catalytic supports were obtained by reacting one symmetric trif...

A series of new diamine monomers, with systematic variations in their chemical structure, by introducing various substituents onto the polymer backbone, have been made to react with two commercial dianhydrides: a very rigid one, pyromellitic dianhydride, (PMDA) and a more flexible one, 2,2′-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6F...

A set of mixed matrix membranes (MMMs) has been prepared by incorporating a triptycene-isatin porous polymer network (PPN) to three aromatic polyimides (one commercial, Matrimid, and two synthesized by us: 6FDA-6FpDA and 6FDA-TMPD) covering a wide range of performances for gas separation. The triptycene-isatin PPN is a highly microporous network ha...

A new generation of porous polymer networks, PPNs, has been obtained in quantitative yield by reacting in superacidic media two rigid trifunctional aromatic monomers (1,3,5-triphenylbenzene and triptycene) with two ketones having electron-withdrawing groups (trifluoroacetophenone and isatin). The resulting amorphous networks are microporous materia...

series of aromatic polyimides has been obtained by the reaction of two dianhydrides, the commercial 2,2'- bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and another having a 5'-tert-butyl-m-terphenyl moiety (BTPDA), with several diamines, including two that have a cardo structure (derived from 9H-fluorene), one of them bearing methyl...

Two series of aromatic poly(ortho-hydroxyamide)s (poly(o-hydroxyamide)s, HPAs) were prepared by reaction of two diamines, 2,2-bis(3-amino-4-hydroxyphenyl) propane (APA) and 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (APAF), with four aromatic diacid chlorides; terephthaloyl dichloride (TPC), isophthaloyl dichloride (IPC), 2,2-bis[4-chloroca...

A new nucleophilic monomer (2,2-bis(3-amino-4-hydroxyphenyl)adamantane, ADHAB) having bulky adamantane groups has been synthesized following an efficient synthetic methodology. The main target of this work was to employ a high thermal stable bulky cycloaliphatic moiety as adamantane to obtain aromatic ortho-hydroxypolyimides (poly(o-hydroxyimide)s)...

The effect of UV-crosslinking on the gas transport properties of two poly(ether ether ketone)s derived from difluorobenzophenone and two bisphenol derivatives, with four (TMBP-DFB) or six (HMBP-DFB) methyl groups, has been studied. The crosslinking reaction was conducted on dense membranes, using polychromatic light, with wavelengths higher than 35...

Two series of novel aromatic polyimides (PIs) containing three polymers each one were prepared using two new aromatic silylated-diamine monomers. These monomeric diamines contain biphenylsilane units and biphenyl moieties in their structures. All PIs were obtained in high yield and the inherent viscosities were in the range of 0.44 to 0.82 dL/g. Po...

Two new polyimides have been obtained from commercial and inexpensive pyromellitic dianhydride and two affordable meta-substituted diamines bearing ortho methyl substituents (i.e., 2,4,6-trimethyl-1,3-phenylene diamine (TMPD) and 5,7-diamino-1,1,4,6-tetramethylindane (TMID)). Due to a combination of dianhydride rigidity and meta substitution, in ad...

Thermally rearranged (TR) polymers are formed through a thermally induced solid-state reaction of polyimides or polyamides that contain nucleophilic reactive groups ortho-positioned to their diamine. Naturally, the transport properties of TR polymers are intimately related to the chemical structure and reactivity of their precursors. Herein, we rep...

Preventing microbial adhesion onto membranes is a crucial issue that determines the durability of the membrane. In this article, we prepared aromatic polyimides (extensively employed for the elaboration of ultrafiltration membranes) containing PEO branches. Four polyimide-g-PEO copolymers were prepared from 6F dianhydride and a novel aromatic diami...

Supporting Information

Reacting ortho-functional poly(hydroxyimide)s via a high-temperature (i.e., 350 degrees C-450 degrees C) solid-state reaction produces polymers with exceptional gas separation properties for separations such as CO2/CH4, CO2/N-2, and H-2/CH4. However, these reactions render these so-called thermally rearranged (TR) polymers insoluble in common solve...

Novel polyhydantoins (PHYs) were synthesized from original aromatic diisocyanates and bisiminoacetates by a two-step polycondensation procedure, which involved the cyclization of polyurea intermediates promoted by acid catalysis. The physical properties of the novel PHYs were evaluated by comparing them with a classical PHY derived from 4,4′-methyl...

The effect of bulky side groups on the molecular mobility and chain packing of three polyimides derived from dianhydrides with m-terphenyl moieties and 2,4,6-trimethyl-m-phenylenediamine has been studied. Moreover, structure–properties relationships in terms of gas transport have been established. One of the polyimides has no side groups, while the...

a b s t r a c t A series of polyimides has been obtained from the experimental diamine 1,4-bis(4-aminophenoxy)2,5-di-tert-butylbenzene (TBAPB) and three commercial dianhydrides, i.e. pyromellitic dianhydride (PMDA), 3,3 ,4,4 -byphenyltetracarboxylic dyanhidride (BPDA) and 4,4 -hexafluoroisopropyliden diphthalic anhy-dride (6FDA), following classica...

Smectic poly(triethylene glycol p,p′-bibenzoate) (PTEB)/clay hybrids were prepared by a solution blending method. Unmodified (cloisite®Na) and two organically modified (cloisite®10A and cloisite®15A) montmorillonites were used. The morphology of the hybrids was characterized by TEM and X-ray diffraction. It has been found that a conventional microc...

Several blends of isotactic polypropylene, iPP, and the liquid crystalline polymer poly(triethylene glycol p,p′-bibenzoate), PTEB, have been prepared with different compositions, and analyzed by scanning electron microscopy, polarizing optical microscopy, infrared spectroscopy, X-ray diffraction with synchrotron radiation, and thermal methods (ther...

The isothermal cold crystallization of poly(ethylene terephthalate)(PET) in cryogenic mechanical alloyed blends of PET and Poly(ethylene naphthalene 2,6-dicarboxilate)(PEN) 1:1 by weight has been investigated by simultaneous small and wide angle X-ray scattering (SAXS and WAXS) and dielectric spectroscopy (DS). For transesterification levels higher...

The dielectric techniques of Thermally Stimulated Depolarization Currents (TSDC) and Dielectric Relaxation Spectroscopy (DRS) were used in order to study the low frequency molecular motions in salicylsalicylic acid. Since this substance is a very effective glass-former, the molecular mobility was analyzed in the glassy state, in the metastable supe...

The isothermal amorphous to smectic phase transformation of a polybibenzoate was investigated by simultaneous medium- and wide-angle X-ray scattering (MAXS and WAXS) and dielectric spectroscopy (DS). By this experimental approach, simultaneously collected information was obtained about the specific changes occurring in both amorphous and smectic ph...

The relaxation behavior of poly(5-acryloxymethyl-5-methyl-1,3-dioxacyclohexane), a polymer containing highly flexible side groups, is studied by broadband dielectric spectroscopy in the frequency and temperature ranges 10(-1)-10(9) Hz and 123-473 K, respectively. Above the glass transition temperature T(g) the dielectric loss in the frequency domai...

The effect of molecular structure on the gamma relaxation dynamics has been studied in a set of aromatic poly(isophthalamide)s. This polymer family differ in the bridge group between phenylene rings [hexafluoroisopropylidene (C(CF(3))(2)) or ether] and also in the presence of t-butyl groups (C(CH(3))(3)) as pendant substituent on the five position...

The isothermal cold crystallization of poly(ethylene terephthalate) was investigated by simultaneous small and wide angle X-ray scattering (SAXS and WAXS) and dielectric spectroscopy (DS). By this experimental approach (SWD), simultaneously collected information was obtained about the specific changes occurring in both crystalline and amorphous pha...

An anomalous enhancement of the segmental dynamics upon crystallization is observed by analyzing the dielectric relaxation of a random copolymer formed by stiff aromatic and flexible aliphatic co-monomeric units. The corresponding aliphatic homopolymer is characterized by a low glass transition temperature. The results show that the characteristic...

The structure−dynamics relationships in random copolymers of poly(butylene adipate) and poly(butylene isophthalate) (PBIPBA) have been investigated by means of X-ray scattering and dielectric loss spectroscopy experiments. The results show that the incorporation of flexible butylene adipate units into the more rigid PBI chain increases the ability...

The isothermal cold crystallization of poly(ethylene naphthalene-2,6-dicarboxylate) was investigated by simultaneous small and wide angle X-ray scattering and dielectric spectroscopy (DS). By this experimental approach, simultaneously collected information was obtained about the specific changes occurring in both crystalline and amorphous phases du...

A method including cryogenic grinding, melt pressing from the molten state, and quenching was used to prepare blends of poly(ethylene terephthalate) (PET) and poly(ethylene naphthalene 2,6-dicarboxylate) (PEN) in which the two phases were highly dispersed. The effect of melt-pressing times on the thermal properties and relaxation behavior of PET/PE...

The dielectric behavior of a family of block copolymers based on poly(butylene terephthalate) (PBT) and aliphatic polycarbonate (PC), with the composition of PBT varying from 100 wt.-% to 40 wt.-%, has been investigated by broad-band dielectric spectroscopy in the frequency range from 10–1 to 109 Hz. At temperatures above the glass transition, the...

The molecular motions in D-sorbitol (D-glucitol) have been studied by thermally stimulated depolarization currents (TSDC) in the temperature region between -160 and 10 °C. The relaxation appears as a broad global peak between -160 and -50 °C and its features were compared with those of the relaxation of maltitol (a D-glucitol derivative). A study o...

In the present work a procedure is proposed to obtain the fragility of a glass from Thermally Stimulated Depolarisation Currents (TSDC) data. From previous TSDC studies on wide series side-chain liquid crystalline polymers, and particularly from a careful thermal sampling analysis of their glass transition relaxation, the fragility parameter was ob...

A side-chain liquid crystalline polyacrylate was investigated by modulated temperature differential scanning calorimetry (MTDSC) in the temperature region of the glass to liquid-crystal transformation. The technique provides the possibility of analysing the temperature dependence of the complex heat capacity, and of its real and imaginary component...

The glass transition relaxation in m-toluidine was studied by thermally stimulated depolarization currents (TSDC). The departure from the zero entropy prediction, also called compensation behavior, was analyzed and the fragility index of the glass-former m-toluidine was calculated from the TSDC data according to a recently proposed procedure. The o...

The technique of thermally stimulated depolarisation currents (TSDC) was used to study the molecular dynamics in two samples of different molecular weight of a side-chain liquid crystalline polymer. The glass transition relaxation was carefully studied in these materials using the thermal sampling procedure. It is suggested that the amplitude of th...

The technique of thermally stimulated depolarisation currents (TSDC) was used to study the molecular dynamics in the fragile glass formers salol, glycerol and maltitol. The glass transition relaxation was carefully studied in these materials using the thermal sampling (TS) procedure. It is suggested that the amplitude of the deviation from the zero...

The synthesis and radical polymerization of 2,2-bis[4-(2-hydroxyethoxy)phenyl]propy monoacrylate are described. The values found at 50 and 60 degrees C for the rate constants ratio, k(p)/k(t)(1/2), are similar to those reported for some acrylic polymers with short side groups at the same temperatures although conflicting results are obtained by com...

The effect of annealing on the permeation of oxygen, nitrogen, and carbon dioxide through coextruded linear low-density polyethylene (LLDPE) films is studied. The results indicate that the permeability coefficient P of nitrogen does not show a definite dependence on the time of annealing, ta, whereas for the other gases this parameter increases wit...

The dielectric activity of poly(monocyclohexylmethylene itaconate) (PMCI) and poly(dicyclohexylmethylene itaconate) (PDCI) in the glassy region and in the glass–rubber transition is studied by thermostimulated discharge current (TSDC) techniques. The spectra obtained by global TSDC experiments show a prominent α-glass–rubber relaxation peak with ma...

The dielectric activity of poly(monocyclohexylmethylene itaconate) (PMCI) and poly(dicyclohexylmethylene itaconate) (PDCI) in the glassy region and in the glass-rubber transition is studied by thermostimulated discharge current (TSDC) techniques. The spectra obtained by global TSDC experiments show a prominent alpha-glass-rubber relaxation peak wit...

The effect of the location of the chlorine atoms on the dynamics, polarity, and thermal properties of the isomers derived from (4-acetyloxyphenyl)-(chlorophenyl)-methanone is discussed. The changes occurring in the dipole moments along the trajectories in their respective conformational spaces are rather large (between 6.0 and 0.3 D) for (4-acetylo...

The considerable dielectric activity exhibited by acrylate polymers containing chlorocyclohexyl side groups is investigated by using both global and partial thermally stimulated depolarization current (TSDC) techniques. The critical interpretation of the spectra obtained by TSDC experiments on poly(2‐chlorocyclohexyl acrylate) (P2CCA), together wit...

In the present report we show real time crystallization experiments PET/PEN blends prepared by a new cryogenic grinding method (3). The main objective of this project is to show that the residence time in the molten state controls the interchange reactions between the blend components. We study this effect following the microstructure development o...