Cardo Groups Research Articles

Synthesis and properties of phenolphthalein‐based thermoplastic poly(ether nitrile imide)s via aromatic nucleophilic substitution polymerization

AbstractAromatic nucleophilic substitution polymerization was used to synthesize five poly(ether nitrile imide)s (PENIs) that include benzonitrile and bulky cardo groups from a mixture of phenolphthalein (PP), 4,4′‐bis(4‐fluorophthalimide) diphenyl ether (4,4′‐BFPI), and 2,6‐difluorobenzonitrile (DFBN). The structure and properties relationship of PENIs with different ratios of DFBN and 4,4′‐BFPI was explored. It was found that the glass transition temperature (Tg) of PENIs decreased from 280 to 260°C, while the temperature of 5% thermal weight loss (T5%) in N2 increased from 429 to 453°C as the benzonitrile content in PENI increased. The produced PENI films had good mechanical characteristics, including tensile strengths of 103–112 MPa, elongations at break of 5.6%–8.2%, and tensile moduli of 2.9–3.4 GPa. Furthermore, the solubility and melt processability were also improved with the introduction of the benzonitrile group. Compared with poly(ether ketone imide)s (PEKIs) and poly(ether sulfone imide)s (PESIs), PENIs with benzonitrile displayed higher Tg, tensile modules, and lower complex viscosity.

A novel thermoplastic water-soluble sizing agent for the interfacial enhancement of carbon fiber/polyether ether ketone composites

Recently reported novel water-soluble polyether ether ketone (PEEK) derivative sizing agents have garnered considerable attention for improving interfacial bonding of carbon fiber-reinforced PEEK (CF/PEEK) composites. However, their extensive application is somewhat limited due to two drawbacks: the use of hazardous organic solvents in production and the retention of emulsifiers in sizing dispersion systems. Herein, an extremely hydrophilic sulfonated PEEK with a cardo group (S-PEEK-WC) was synthesized and used to prepare a water-soluble sizing agent. The S-PEEK-WC exhibits excellent thermal stability, with a 5 % decomposition temperature of 446.5 °C, and its aqueous solution remains stable for over six months. A robust interphase was also constructed in the CF/PEEK composites through multiple physicochemical interactions. Compared with the de-sized CF/PEEK composites, the interlaminar shear strength, flexural strength and interfacial shear strength of the CF2/PEEK composites improved by 57.9 %, 56.3 % and 44.8 %, respectively. This approach may shed some light on the development of a valid and environmentally friendly method for preparing water-soluble sizing agents of polyaryletherketone.

Novel polyaryl isatin polyelectrolytes with flexible monomers for anion exchange membrane fuel cells

The stability of the anion exchange polyelectrolytes is closely tied to the durability of anion exchange membrane fuel cells. Given their excellent alkali resistance, ether-free polymer backbones have attracted considerable attention for use in anion-exchange polyelectrolytes. Herein, a series of side-chain-type poly(terphenylene-co-dibenzyl N-(6-bromohexyl)-isatin) copolymers (QAPTDBHI-n) were synthesized via superacid-catalyzed polymerization and a subsequent quaternization reaction. The cyclic cardo groups in the backbones enabled the formation of nanovoids, which facilitated ionic clusters’ self-aggregation. The introduction of flexible bibenzyl monomers provided the polymers with a spatially foldable structure, promoting the aggregation of ion clusters and strengthening interchain interactions. Compared with the membrane without flexible monomers, QAPTDBHI-n membranes exhibited higher hydroxide conductivity (>115 mS cm−1 at 80 °C), outstanding mechanical stability (tensile strength: 50.91–60.76 MPa, elongation at break: 14.27%–26.06%), and superior alkali resistance (1 M NaOH at 80°C for >1500 h and <9.5% OH− conductivity loss). Regarding fuel cell performance, the AEMFC based on QAPTDBHI-40 ionomer achieved a peak power density of 1.14 W cm−2 (H2–O2) and 0.86 W cm−2 (H2-Air, CO2 free) at 80 °C due to its higher water uptake, OH− conductivity, and lower phenyl concentration.

Pyrrolidinium-functionalized Cardo (TPM) poly(arylene ether sulfone)s membranes for acid recovery: The effects of Cardo (TPM) microstructures

To explore the intrinsic correlation between the rigidity and distortion degree of polymer backbones and the diffusion dialysis (DD) performance of anion exchange membranes (AEMs), pyrrolidinium-functionalized poly(arylene ether sulfone)s containing different Cardo (TPM) moieties were prepared. The structures, properties and DD performance of above AEMs were systematically evaluated. As the Cardo (TPM) group angle increased, the d-spacing, fractional free volume, and membrane area resistance increased, and the microphase separation structures, hydrophilicity, and acid flux decreased, mainly because larger Cardo (TPM) group angles are unfavourable for the close packing of polymer chains in space. Both the Cardo-type and TPM-type AEMs exhibited universal ultrahigh H+/Fe2+ selectivity (S > 3819), which was mainly attributed to the synergistic influence of their rigid narrow ion transport channels, small pore diameter (0.48–0.62 nm) and narrow pore size distribution (0.24–0.68 Å). Additionally, due to the high-density amide groups of TPM units, which decreased the hydrophobicity of the polymer skeleton and induced the formation of an additional transport pathway for Fe2+ through hydrogen bonding interactions, the TPM-type AEMs showed both lower acid flux and selectivity, suggesting that the structure of hydrophilic auxiliary groups should be carefully designed when improving the DD performance of AEMs.

Pillared Carbon Membranes Derived from Cardo Polymers.

Carbon molecular sieve membranes (CMSMs) were prepared by carbonizing the high free volume polyimide BTDA-BAF that is obtained from the reaction of benzophenone-3,3',4,4'-tetracarboxylic dianhydride (BTDA) and 9,9-bis(4-aminophenyl) fluorene (BAF). The bulky cardo groups prevented a tight packing and rotation of the chains that leads to high permeabilities of their CMSMs. The incorporation of metal-organic polyhedra 18 (MOP-18, a copper-based MOP) in the BTDA-BAF polymer before pyrolysis at 550 °C prevented the collapse of the pores and the aging of the CMSMs. It was found that upon decomposition of MOP-18, a distribution of copper nanoparticles minimized the collapse of the graphitic sheets that formed the micropores and mesopores in the CMSM. The pillared CMSMs displayed CO2 and CH4 permeabilities of 12,729 and 659 Barrer, respectively, with a CO2/CH4 selectivity of 19.3 after 3 weeks of aging. The permselectivity properties of these membranes was determined to be at the 2019 Robeson upper bound. In contrast, the CMSMs from pure BTDA-BAF aged three times faster than the CMSMs from MOP-18/BTDA-BAF and exhibited lower CO2 and CH4 permeabilities of 5337 and 573 Barrer, respectively, with a CO2/CH4 selectivity of 9.3. The non-pillared CMSMs performed below the upper bound.

Fluorinated-cardo-based Co-polyimide membranes with enhanced selectivity for CO2 separation

The application of fluorinated polyimides in the field of gas separation membranes is becoming increasingly widespread due to their strong thermal and chemical stability. However, overcoming the separation trade-off between gas permeability and selectivity of polyimides remains a key hurdle, requiring the design of new polyimides with tailorable free volume and microstructures. Herein, we synthesized a series of polyimides containing rigid cardo groups with C-F bonds (i.e. FFDA) to increase the packing efficiency of polymer chains and thus enhance the gas selectivity of membranes. Moreover, DAM segments were copolymerized with FFDA to finely regulate the fractional free volume and produce 6FDA-FFDA/DAM copolyimide to boost gas separation performance. The CO2 permeability and CO2/CH4 selectivity of fluorinated-cardo-based copolyimide 6FDA-FFDA/DAM (1:1) are 203.4 Barrer and 43.4, respectively, performing beyond the 2008 Robeson upper bound for CO2/CH4 separation. The design principles in this work lay the groundwork for fabricating desirable polymeric membranes with tailored microstructures and properties for selective CO2 separation.

Structure and Properties of Low Dielectric Constant Polyetherimide Films Containing-CF3 and Cardo Groups

Structure and Properties of Low Dielectric Constant Polyetherimide Films Containing-CF3 and Cardo Groups

Cardopoly(arylene ether sulfone)s membranes bearing N-cyclic cationic groups enable high performance during both diffusion dialysis and electrodialysis

To investigate the relationships between the permselectivities and physicochemical structures of AEMs during diffusive dialysis (DD) and electrodialysis (ED), a series of cardopoly(arylene ether sulfone) membranes with different N-cyclic QA cations, controllable microphase separation structures and ultrahigh H+/Fe2+ selectivity during DD were prepared, and their permselectivity during ED and DD was systematically explored. The AEMs showed universally higher H+/Mn+ selectivities than known commercial and polymer-based membranes due to their rigid and contorted structures containing both cardo groups and pendant N-cyclic QA cations, which enabled formation of unique nano ion channels. During ED, the AEMs also displayed high Cl−/SO42− permselectivities, which was associated with microphase separation. For example, the prepared membrane with the best microphase separation exhibited the highest permselectivity (PSO42−Cl−=8.54) that was 5 times higher than that of the commercial ED membrane (PSO42−Cl−=1.6). The ED performance of the prepared AEMs was influenced by the distance between the AEMs and CEMs, and a shorter distance resulted in better ED performance. In addition, AEMs with better microphase separation were preferable for desalination because of enhanced dissociation and mobility of counterions under high current densities and low feeding salt concentrations. These findings may suggest new designs for high-performance ED and DD membranes.

Recyclable palladium-catalyzed synthesis of new cardo poly(amide-imide)s from diiodo imides, aromatic diamines containing cardo groups, and carbon monoxide

Recyclable palladium-catalyzed synthesis of new cardo poly(amide-imide)s from diiodo imides, aromatic diamines containing cardo groups, and carbon monoxide

PEEK-WC-Based Mixed Matrix Membranes Containing Polyimine Cages for Gas Separation.

Membrane-based processes are taking a more and more prominent position in the search for sustainable and energy-efficient gas separation applications. It is known that the separation performance of pure polymers may significantly be improved by the dispersion of suitable filler materials in the polymer matrix, to produce so-called mixed matrix membranes. In the present work, four different organic cages were dispersed in the poly(ether ether ketone) with cardo group, PEEK-WC. The m-xylyl imine and furanyl imine-based fillers yielded mechanically robust and selective films after silicone coating. Instead, poor dispersion of p-xylyl imine and diphenyl imine cages did not allow the formation of selective films. The H2, He, O2, N2, CH4, and CO2 pure gas permeability of the neat polymer and the MMMs were measured, and the effect of filler was compared with the maximum limits expected for infinitely permeable and impermeable fillers, according to the Maxwell model. Time lag measurements allowed the calculation of the diffusion coefficient and demonstrated that 20 wt % of furanyl imine cage strongly increased the diffusion coefficient of the bulkier gases and decreased the diffusion selectivity, whereas the m-xylyl imine cage slightly increased the diffusion coefficient and improved the size-selectivity. The performance and properties of the membranes were discussed in relation to their composition and morphology.

Synthesis of novel aromatic polyamides containing both sulfone linkages and cardo groups by a recyclable palladium-catalyzed carbonylation and condensation polymerization

A series of novel aromatic polyamides containing both sulfone linkages and cardo groups were synthesized via a heterogeneous palladium-catalyzed carbonylation and condensation reaction of aromatic diiodides bearing ether sulfone linkages, carbon monoxide, and aromatic diamines with cardo groups. Polycondensation reaction proceeded smoothly under 1 atm of CO at 120 °C in N,N-dimethylacetamide (DMAc) by using a bidentate phosphine ligand-modified magnetic nanoparticles-anchored palladium complex [2P-Fe3O4@SiO2-PdCl2] as a recyclable catalyst with 1,8-diazabicycle[5,4,0]-7-undecene (DBU) as a base, furnishing cardo poly(ether sulfone amide)s with inherent viscosities between 0.70 and 0.77 dL/g. The resulting polyamides could be readily dissolved in polar aprotic organic solvents and even dissolved in less polar pyridine and tetrahydrofuran at room temperature and could be easily converted into flexible, transparent, and tough films via casting from their solutions in DMAc. These polymers exhibited excellent thermal stability with the glass transition temperatures between 241 and 283 °C and the temperatures at 5% weight loss ranging from 438 to 475 °C in an atmosphere of nitrogen. The polyamide films displayed good mechanical behavior with tensile strengths of 78.8–84.4 MPa, tensile moduli of 2.08–2.57 GPa, and elongations at breakage of 10.2–12.5%, and optically high transparency with cut-off wavelengths in the range of 338–368 nm.

Synthesis of novel aromatic polyamides containing cardo groups and triphenylphosphine oxide structures by a heterogeneous palladium-catalyzed carbonylation and condensation reaction

New aromatic polyamides containing cardo groups and triphenylphosphine oxide structures were synthesized by a heterogeneous palladium-catalyzed carbonylation and condensation of bis(4-(3-iodophenoxy)phenyl)phenylphosphine oxide (BIPPO), aromatic diamines bearing cardo groups, and carbon monoxide. Polycondensations were carried out in N,N-dimethylacetamide under 1 atm of CO at 120 °C in the presence of a magnetically recyclable heterogeneous palladium catalyst and 1,8-diaza-bicyclo[5,4,0]-7-undecene (DBU) and afforded novel aromatic polyamides with inherent viscosities between 0.72 and 0.76 dL/g. All the polyamides were quite soluble in dipolar aprotic solvents and pyridine and could be converted into transparent, flexible, and tough polyamide films by casting from DMAc solutions. These polymers exhibited high thermal and thermooxidative stability with the glass transition temperatures of 237 °C–256 °C, the temperatures at 5% weight loss of 448 °C–465 °C in air. All the phosphorus-containing polyamides self-extinguished as soon as the flame was removed, and the limited oxygen indices (LOIs) of these polymers were in the range of 39%–44%. The polymer films also showed good mechanical properties and high optical transparency.

Synthesis of Organosoluble Polyimides and Optical Fiber Protective Coatings on Their Basis

Homo- and copolyimides containing F, Cl, or Si atoms and COOH, OH, and cardo groups are synthesized by one-step high-temperature polycyclocondensation. It is shown that the structure of the polymer affects its solubility, thermal, mechanical, and optical properties and use as a coating. The resulting polymers with ηinh = 0.3–1.3 dL/g are characterized by high heat resistance and thermal stability (240°C ≤ Tg ≤ 375°C, 440°C ≤ T10% ≤ 580°C) and also form high-strength films (55 MPa ≤ σ ≤ 140 MPa; 1.1 GPa ≤ E ≤ 2.8 GPa). The developed polyimides are promising as new highly thermostable protective coatings, in particular, of optical fibers, whose mechanical properties do not change after prolonged exposure at 300°C.

The Antifriction Properties of Amorphous Poly(Arylene Ether Ketone) Copolymers with a Low Content of Cardo Groups

The causes of an abrupt decrease in the wear and in the friction coefficient from 0.6 to 0.24 for poly(arylene ether ketone) copolymers containing 10, 15, and 25 mol % of cardo bisphenol moieties in the main chain have been investigated. The presence of cardo groups in the copolymers promotes an increase in the microhardness from 12 to 22 kgf/mm2 and maintains a high antifrictionality as a parameter that characterizes the dispersion interaction energy contribution to the total energy of the intermolecular interaction. The XPS examination of the copolymers has shown that only in the case of poly(arylene ether ketone) copolymer containing 10 mol % cardo groups, wear products do not undergo any considerable structural changes in the friction process. The studies demonstrated that a significant improvement of friction-and-wear parameters in the case of a poly(arylene ether ketone) copolymer containing a 10 mol % of cardo groups is caused by an optimal combination of increasing microhardness, formation of a discrete surface, and by maintaining a high antifrictionality. With increasing cardo group content in the copolymers to 15 and 25%, a gradual increase in the friction coefficient to 0.5 and 0.75, respectively, was observed.

Synthesis of cardo poly(arylene ether ketone amide)s by heterogeneous palladium-catalyzed polycondensation of aromatic diiodides, aromatic diamines containing cardo groups and CO

New cardo poly(arylene ether ketone amide)s were synthesized by heterogeneous palladium-catalyzed carbonylative polycondensation of aromatic diiodides with ether–ketone linkages, aromatic diamines bearing cardo groups, and carbon monoxide. Polymerizations were conducted in N,N-dimethylacetamide (DMAc) at 120 °C in the presence of a bidentate phosphino-functionalized magnetic nanoparticles-immobilized palladium complex [Fe3O4@SiO2-2P-PdCl2] and 1,8-diazabicyclo[5,4,0]-7-undecene (DBU), yielding a series of cardo poly(arylene ether ketone amide)s with inherent viscosities up to 0.77 dL/g. All the polymers were readily soluble in various dipolar aprotic solvents at room temperature. These polymers showed good thermal stability with the glass transition temperature of 223–289 °C, the temperature at 5% weight loss of 441–464 °C in nitrogen. These cardo poly(arylene ether ketone amide)s could afford transparent, flexible, and strong films by solution-casting with good tensile properties. These polymer films exhibited lower dielectric constants, lower water uptakes, and higher optical transparency. Furthermore, this heterogeneous palladium catalyst can facilely be separated from the reaction mixture by simply applying an external magnet and recycled at least eight times with almost consistent activity.

Experimental and computational study on direct fluorination of PEEKWC membranes

Membranes modification of poly-ether-ether ketone with cardo group (PEEK-WC) by direct fluorination and simulations was achieved in order to investigate the fluorinations effect on the morphology and gas perm-selectivity of PEEK-WC membranes. The thicknesses of the fluorinated layers as function of the fluorination extent were measured and then their average densities were obtained. The structures of two fluorinated PEEK-WC monomers were defined through quantum chemical calculations exploiting the in situ evolution of the membranes composition. The fluorinated monomers were then used to build chain models via molecular dynamics simulations realizing the scale increase. The analysis of free volume and permeability of light apolar gases (He, H2, O2, N2 and CH4) were finally performed. The fractional free volume drastically increases after the direct fluorination of the PEEK-WC and the free volume connections show that the high fluorinated PEEK-WC models present well-defined channels inside their structure similarly to fluorinated polymers obtained not by direct fluorination. The gases permeability resulted significantly larger with respect to pristine PEEK-WC; in particular, for low fluorination membranes, the permeability is significantly lower compared to samples with high fluorination amount. This result is in agreement with the free volumes analysis. For high degree of fluorination, the polymer shows an increase in free volume and, in parallel, an increase in permeability however a reduction in selectivity compared to low fluorinated polymer. This behaviour is in agreement with experimental data available for other polymer membranes.

Cardo Copolymers: A Friction–Chemical Structure Relationship

Poly(arylene ether ketone)s containing pendent bulky cardo groups in the monomer unit, while having a high antifrictionality, do not obey the earlier established regularity of the relationship between chemical structure and friction. The necessity of taking into account the flexibility of macromolecules is an additional factor for these polymers. To XPS study the tribochemical processes of carded polymers, “flexible chain” and “rigid chain” copolyarylene ether ketones (co-PAEKs) were used. It was found that the flexible moieties of the macromolecule favor a decrease in the friction coefficient and an increase in the wear resistance. Impaired tribochemical indices of the rigid cardo polymer are caused by active tribodestruction of phthalimidine groups.

Synthesis of new fluorinated aromatic poly (ether ketone amide)s containing cardo structures by a heterogeneous palladium‐catalyzed carbonylative polycondensation

New fluorinated aromatic poly (ether ketone amide)s containing cardo structures were prepared by a heterogeneous palladium‐catalyzed polycondensation of fluorinated aromatic diiodides with ether ketone units, aromatic diamines containing cardo groups, and CO. Polymerizations were conducted in N,N‐dimethylacetamide at 120°C using 6 mol% of magnetic nanoparticles‐supported bidentate phosphine palladium (II) complex [Fe3O4@SiO2‐2P‐PdCl2] as catalyst and 1,8‐diazabicyclo[5,4,0]‐7‐undecene as base and resulted in fluorinated cardo poly (ether ketone amide)s with inherent viscosities up to 0.75 dL/g. All the polymers were readily soluble in many organic solvents and could afford transparent, flexible, and strong films by solution casting. These polymers showed good thermal stability with the glass transition temperature of 237°C–258°C, the temperature at 5% weight loss of 462°C–477°C in nitrogen. These polymer films also exhibited good mechanical properties, excellent electrical and dielectric performance, and high optical transparency. The incorporation of bulky fluorinated groups and cardo structures into polymer backbone has played an important role in the improvement of solubility, dielectric performance, and optical properties. Importantly, the heterogeneous palladium catalyst can easily be recovered from the reaction mixture by simply applying an external magnet and recycled up to 7 times without significant loss of catalytic activity.

Synthesis and properties of bismaleimide resins containing phthalide cardo and cyano groups

Two novel n ≈ 1 oligomeric bismaleimide monomers containing phthalide cardo and cyano groups (PCBMI and MCBMI) were designed and synthesized. The chemical structures of the monomers were confirmed from proton nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy. Both BMIs exhibit good solubility in common organic solvents, enabling easy solution processing. Thermal curing behaviors of the monomers were investigated by differential scanning calorimetry, displaying broad exothermic peaks and large thermal processing windows. Furthermore, PCBMI/carbon fiber composites were prepared, with their thermal stability and mechanical properties investigated. Thermogravimetric analysis and test of interlaminar shear strength indicated that the thermal polymerization of cyano groups improved the heat resistance of BMI resins and enhanced the interfacial adhesion at higher temperature.

Fluorene‐containing cardo and fully aromatic single ion conducting polymer electrolyte for room temperature, high performance lithium ion batteries

AbstractThe self‐assembly process between rigid fully aromatic single ion conducting polymer electrolytes (SIPEs) and flexible aliphatic binder for fabrication of macro‐scale porosity of membrane for enhancement of ionic conductivity has been demonstrated in our previous works. In this article, the bulky and rigid fluorene cardo groups are successfully introduced into the fully aromatic polymeric backbone to synthesize the fluorene‐containing cardo fully aromatic single ion conducting polymer electrolyte (fca‐SIPE). The synthesized fca‐SIPE is then blended with a flexible aliphatic PVDF‐HFP binder to prepare fca‐SIPE membrane via a solution cast method. By comparing with results of the previous works, in this case, not only the macro‐scale porous morphology derived from the self‐assembly process between PVDF‐HFP and fca‐SIPE, but also the interior nano‐scale lithium ion transport pathway throughout the free volume formed by the fluorene groups is obtained. The effect of the fluorene group on the key properties of membrane, such as ionic conductivity and battery performance, is systematically investigated. The excellent performance at high C‐rates at room temperature is demonstrated.