Nucleophilic Aromatic Substitution Polymerization Research Articles

Enhanced crystallinity, mechanical and dielectric properties of biphenyl polyarylene ether nitriles by unidirectional hot-stretching

In this work, biphenyl polyarylene ether nitrile (BP-PEN) was synthesized via a solution nucleophilic aromatic substitution polymerization of biphenyl (BP) with 2, 6-dichlorobenzonitrile (DCBN). BP-PEN films were prepared by solution-casting process and then were unidirectional stretched with different ratios (0, 50, 100, 150 and 200 %) under high temperature (280, 300 and 320 °C) to enhance their crystallinity and degree of orientation. Results showed that the thermal, mechanical, crystallinity and dielectric properties of the BP-PEN films were significantly enhanced after the unidirectional hot-stretching process. The glass transition temperatures (T g) of the films hot-stretched at 280 °C range from 214.2 to 218.2 °C and melting point was in the range from 330.4 to 346.3 °C. Besides, the percent crystallinity of them was increased from 4.92 to 19.16 %. Moreover the tensile strength and modulus of them increased from 121 to 451 MPa and from 1943 to 4938 MPa, respectively. Compared with BP-PEN films without stretch treatment, the dielectric constant of the film stretched at 280 °C also increased from 4.0 to 6.7 (1 kHz).

Synthesis of organosoluble and light‐colored cardo polyimides via aromatic nucleophilic substitution polymerization

A series of cardo polyimides (PIs) containing large‐volume cardo groups were prepared via aromatic nucleophilic substitution polymerization of bisphenols and bis(fluorophthalimide)s. This series of cardo PIs show excellent solubility in a variety of organic solvents. The glass transition temperatures (Tgs) of these PIs are recorded from 217°C to 293°C, the 5% weight loss temperatures (T5%) reach up to 495–536°C in air and 487–531°C in nitrogen, respectively. Flexible films, which could be cast from the polymer solutions, exhibit good mechanical properties with tensile strengths of 118–127 MPa, elongations at break of 10.6–15.4% and tensile moduli of 2.3–2.8 GPa. Their films with cut‐off wavelengths from 342 to 423 nm are essentially colorless, and the transmittance of these cardo polyimide films is over 80% between 450 and 800 nm. It is noted that cardo PIs possess better solubility, higher glass transition temperature, and better optical transparency than linear PIs. Copyright © 2015 John Wiley & Sons, Ltd.

Direct polymerization of a novel sulfonated poly(arylene ether ketone sulfone)/sulfonated poly(vinylalcohol) crosslinked membrane for direct methanol fuel cell applications

Sulfonated poly(arylene ether ketone sulfone) copolymers containing carboxylic acid groups (C-SPAEKS) were prepared by direct aromatic nucleophilic substitution polymerization. Novel C-SPAEKS-based crosslinked membranes containing different amounts of sulfonated poly(vinyl alcohol) (SPVA) were fabricated. The Fourier transform infrared and 1H NMR analyses showed the presence of carboxylic acid and sulfonic acid groups, as well as ester bonds in the crosslinked membranes. As expected, the crosslinked membranes exhibited enhanced thermal stability relative to the uncrosslinked membranes. Both the atomic force microscopy (AFM) and transmission electron microscopy (TEM) images clearly show the hydrophilic domains and hydrophobic polymer backbone. The methanol permeability coefficients of the crosslinked membranes with the SPVA content from 10% to 90% ranged from 10.67×10−7cm2s−1 to 1.05×10−7cm2s−1 at 25°C, and from 22.24×10−7cm2s−1 to 2.41×10−7cm2s−1 at 60°C, which are much lower than those of C-SPAEKS membrane (12.79×10−7cm2s−1 at 25°C and 26.85×10−7cm2s−1 at 60°C). The proton conductivities of all the crosslinked membranes were above 10−2Scm−1, satisfying the requirement of fuel cells. Furthermore, the crosslinked membranes exhibited a high selectivity, further confirming that this series of crosslinked membranes are potential candidates as new polymeric electrolyte materials for direct methanol fuel cells.

Synthesis and properties of cross-linkable poly(arylene ether nitrile)s containing side propenyl groups

Cross-linkable poly(arylene ether nitrile)s containing side propenyl groups (DPEN) were synthesized through nucleophilic aromatic substitution polymerization from biphenol, 2,2′-diallylbisphenol A (DBA), and 2,6-dichlorobenzonitrile. The structures of resultant copolymers were characterized by Fourier transform infrared and proton nuclear magnetic resonance spectroscopies. The properties of copolymers were investigated by thermal (differential scanning calorimetry and thermogravimetric analysis) analysis, inherent viscosity measurements, and mechanical tests. The results showed that allyl groups rearranged into propenyl groups during the polymerization. The copolymers with increasing content of DBA had high glass transition temperatures ranging from 207°C to 169°C and good thermal and thermo-oxidative stability with the 5 wt% loss temperatures in the range of 511–423°C under nitrogen and 471–402°C in air atmospheres, respectively. They also exhibited good mechanical property with tensile strength of 105–79 MPa. Meanwhile, the cross-linking reaction was studied through heat treatment. The result showed that the properties of DPEN containing side propenyl groups changed obviously after heat treatment, due to the fact that the double bond of PEN can be readily cross-linked to form net-shape polymers at high temperature.

Synthesis of high performance phenolphthalein-based cardo poly(ether ketone imide)s via aromatic nucleophilic substitution polymerization

A series of cardo poly(ether ketone imide)s (PEKI-C) containing large-volume bulky phthalide groups were prepared by aromatic nucleophilic substitution reaction of commercially available phenolphthalein and 4,4′-bis(4-fluorophthalimido)diphenyl ether/4,4′-difluorobenzophenone. The glass transition temperatures (Tgs) increased from 221 to 278 °C with increasing the content of 4,4′-bis(4-fluorophthalimido)diphenyl ether moiety in the copolymerization. The 5% weight loss temperatures (T5%) of PEKI-C (a–e) reached up to 472–495 °C in nitrogen and 466–481 °C in air. Flexible films, which could be easily cast from the polymer solutions, exhibited good mechanical properties with tensile strengths of 73–124 MPa, elongations at break of 9.7–12.8%, and tensile moduli of 2.2–2.8 GPa. Their films with cut-off wavelengths from 336 to 368 nm were transparent and essentially colorless. It is noted that the Tg, T5%, tensile strengths, elongations at break, and tensile moduli of PEKI-C (a–e) increased with increasing the content of 4,4′-bis(4-fluorophthalimido)diphenyl ether in the copolymerization.

Novel polyarylene ether nitrile nanofibrous mats with fluorescence and controllable surface morphology

A novel series of fluorescent polyarylene ether nitrile (PEN) copolymers were successfully synthesized via nucleophilic aromatic substitution polymerization reaction from 2,6-dichlorobenzonitrile, 4, 4-Bis(4-hydroxyphenyl)valeric acid and biphenol. The obtained carboxylated PENs exhibit tunable fluorescent emission depending on the backbone structures of the copolymer. Most importantly, nanoporous mats were fabricated by electrospinning the synthesized PEN copolymers in the presence of water-soluble polyvinylpyrrolidone (PVP), followed by a selective removing PVP from washing with H2O in postelectrospinning progress. Thanks to their nanoscale porous structures and tunable fluorescent emission, the prepared PEN nano-fibers would find potential applications in chemosensing.

Thermal and thermo-oxidative degradation of some heterocyclic aromatic polyethers containing phenylquinoxaline and/or 1,3,4-oxadiazole rings

Poly(phenylquinoxaline ether ketone) Q-DFB and poly(phenylquinoxaline-1,3,4-oxadiazole ether) Ox-Q were synthesized by the conventional aromatic nucleophilic substitution polymerization technique of bis(hydroxyphenylquinoxaline) with 4,4′-difluorodiphenyl ketone or with 2,5-bis(4-fluorophenyl)-1,3,4-oxadiazole, respectively. Poly(1,3,4-oxadiazole ether) Ox-BisA was prepared by the same synthetic method from 2,5-bis(4-fluorophenyl)-1,3,4-oxadiazole, and 2,2-bis(4-hydroxyphenyl) propane. The polymers were characterized by Fourier transform infrared (FTIR) spectroscopy, solubility, the inherent viscosity and thermogravimetric analysis (TGA). The thermogravimetric analyzes were effectuated under air or helium atmosphere. Information on thermal decomposition onset in the two atmospheres was collected by using the TG/MS/FTIR technique (simultaneous mass spectrometry and Fourier transform infrared spectroscopy of off-gases from a thermogravimetric analyzer). The influence of phenylquinoxaline and 1,3,4-oxadiazole rings on the thermodegradation behavior of the polymers was evidenced.

Preparation and Characterizations of Novel Ultrafiltration Membranes from Sulfonated Poly (Arylene Ether Sulfone)s

Sulfonated poly(arylene ether sulfone)s (SPAES) with different sulfonation degree (DS) were synthesized through aromatic nucleophilic substitution polymerization, and subsequently used to prepare ultrafiltration membranes by the phase inversion method. The performance and morphological structures of the prepared SPAES membranes were investigated and evaluated for ultrafiltration applications. With DS of 3%, the prepared ultrafiltration membrane showed the largest water permeability with bovine serum albumin rejection over 99%.

Synthesis and properties of sulfonated polyarylene ether nitrile copolymers for PEM with high thermal stability

A series of sulfonated polyarylene ether nitrile copolymers (SPEN) were synthesized by the nucleophilic aromatic substitution polymerization of 2, 6-difluorobenzonitrile with different ratios of hydroquinonesulfonic acid potassium salt and bisphenol A in the presence of K2CO3. The synthesized SPEN exhibited good solubility in polar organic solvents such as N-methylpyrrolidone, N, N’-dimethylformamide, dimethylacetylamide and dimethylsulfoxide. These copolymers can be easily processed into membranes by a facile solution-casting method. The representative membranes in acid form were obtained and their chemical structures were characterized by Fourier transform infrared analysis. The thermal properties, mechanical properties, proton conductivity, water uptake and ion exchange capacity of copolymer membranes were also investigated. The results showed that they had high glass transition temperatures ranging from 189 °C to 245 °C and good thermal and thermo-oxidative stability with the 5 wt.% loss temperatures in the range of 328–378 °C in nitrogen and 329–379 °C in air, respectively. They also exhibited good mechanical property with the tensile strength in the range of 45–62 MPa in the dry state and 23–45 MPa in the wet state. Furthermore, these copolymer membranes exhibited good water uptake ranging from 9.7 % to 57.74 % and outstanding ion exchange capacity in the range of 0.64–1.99 mmol/g. Thus, the membranes had good proton conductivities in the range of 2.47 × 10−5–1.71 × 10−3 s/cm at room temperature and 55 % RH.

Highly Efficient Blue Electrophosphorescent Polymers with Fluorinated Poly(arylene ether phosphine oxide) as Backbone

In view of the tolerance of F atoms in FIrpic to the nucleophilic aromatic substitution polymerization, an activated fluorinated poly(arylene ether phosphine oxide) backbone is used to construct novel blue electrophosphorescent polymers containing FIrpic as the blue emitter, because they can be synthesized under a milder temperature of 120 °C. Compared with the counterparts prepared at high temperature (165 °C), unexpected bathochromic shift is successfully avoided, and a state-of-art luminous efficiency as high as 19.4 cd A(-1) is achieved. The efficiency is comparable to the corresponding physical blend system, which indicates that the fluorinated poly(arylene ether phosphine oxide) has the potential to be used as the platform for the development of high-performance all-phosphorescent white polymer based on single polymer system.

Studies on the Relationship of Polymer Backbone Rigidity and Properties for Proton Exchange Membranes Derived from Sulfonated Polys(Arylene Ether Sulfone)

A series of novel sulfonated poly(arylene ether sulfone) (SPAES) copolymers were successfully synthesized from hexafluoro bisphenol A (6F-BPA), 9,9’-bis(4-hydroxyphenyl) fluorene (BHPF), 4,4’-difluorodiphenyl sulfone (DFDPS) and 3,3’-disulfonate-4,4’-difluorodiphenyl sulfone (SDFDPS) via aromatic nucleophilic substitution polymerization, and subsequently used to prepare proton exchange membranes. By adjusting the ratio of 6F-BPA to BHPF, the influence of the rigidity of polymer backbone on the properties of the prepared membranes was investigated in detail. The results indicated that the SPAES membranes had better stability towards water but lowered water uptake and proton conductivity with the increase in the polymer backbone rigidity.

Synthesis and dielectric properties of polyarylene ether nitriles with high thermal stability and high mechanical strength

A series of polyarylene ether nitriles were synthesized by the nucleophilic aromatic substitution polymerization of 2, 6-dichlorobenzonitrile with various bisphenol monomers. Owing to the different structural units, the derived copolymers showed different glass transition temperatures in the range of 166–260 °C. Moreover, they all showed good film-forming properties and high mechanical strength ranging from 75 MPa to 117 MPa, and also exhibited high thermal stability with the 5% weight loss temperatures ranging from 373 °C to 498 °C. Furthermore, both the dielectric constant and dielectric loss were found to be relatively stable with respect to temperature before the turning point temperature, which is very near to the glass transition temperature.

Synthesis of high glass transition temperature fluorescent polyarylene ether nitrile copolymers

A novel series of fluorescent copolymers were synthesized by the nucleophilic aromatic substitution polymerization of 2, 6-dichlorobenzonitrile with different ratios of phenolphthalein to phenolphthalin. The derived copolymers showed good solubility in common organic solvents at room temperature and good film-forming properties. These copolymers were characterized by Fourier transform infrared, proton nuclear magnetic resonance, ultraviolet–visible absorption, fluorescence spectroscopy, differential scanning calorimetry and thermogravimetric analysis. They had high glass transition temperatures ranging from 237 °C to 260 °C and good thermal stability with the 5% weight loss temperatures in the range of 373–455 °C. Furthermore, the copolymers exhibited characteristic bimodal ultraviolet–visible absorption and unimodal fluorescence emission in both solution and film states.

Poly(arylene sulfide)s by nucleophilic aromatic substitution polymerization of 2,7‐difluorothianthrene

AbstractPoly(thianthrene phenylene sulfide) and poly(thianthrene sulfide) have been prepared by nucleophilic aromatic substitution polymerization of the activated monomer 2,7‐difluorothianthrene with bis thiophenoxide and sulfide nucleophiles, respectively. The resulting polymers are thermally stable, amorphous materials that have been characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), gel permeation chromatography (GPC), matrix‐assisted laser desorption/ionization‐time‐of‐flight (MALDI‐TOF) mass spectrometry, UV‐Vis spectroscopy, refractometry, and intrinsic viscosity (IV) measurements. The polymers produced exhibit 5% weight loss values approaching 500 °C in inert and air atmospheres and glass transition temperatures that range from 149 to 210 °C. Poly(thianthrene phenylene sulfide) with a number average molecular weight of 22,100 g/mol has been synthesized with an IV in DMPU of 0.62 dL/g at 30 °C. Creasable films of this polymer have been prepared by solvent casting and melt pressing at 250 °C. Films of poly(thianthrene phenylene sulfide) exhibit transparencies greater than 50% at wavelengths exceeding 400 nm and a high refractive index value of 1.692 at a wavelength of 633 nm, making the polymer interesting for optical applications. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2453–2461, 2009

Convenient Synthesis of Aromaric Poly(ether ketone)s Containing Alicyclic Units

Aromatic poly(ether ketone)s containing cyclohexanediyl and adamantanediyl units were synthesized through nucleophilic aromatic substitution polymerization of alicyclic difluorides with bisphenols in the presence of K2CO3 in NMP. Most of the poly(ether ketone)s thus synthesized are soluble in organic solvents such as CHCl3 and THF. Glass transition temperatures (Tg’s) of the polymers and temperatures where 5% weight losses occur are in the region of 146–199 °C and 432–500 °C, respectively, which shows that the poly(ether ketone)s have excellent thermal stability. UV spectra of the poly(ether ketone)s revealed that they are sufficiently transparent in the wavelength above 310 nm.

Synthesis and characterization of poly(aryl ether sulfone) copolymers containing terphenyl groups in the backbone

A linear rigid bisphenol monomer, 4,4′-dihydroxyterphenyl (DHTP), has been incorporated into poly(aryl ether sulfone)s (PAESs) in a study to impart crystallization to these amorphous polymers. The PAES made from DHTP and dichlorodiphenylsulfone (DCDPS) is semi-crystalline but not soluble or thermally processable. Three bisphenols, 4,4′-isopropylidenediphenol (BPA), 4,4′-(hexafluoroisopropylidene)diphenol (BPAF) and 4,4′-dihydroxybiphenyl (BP), have been copolymerized with DHTP and DCDPS in order to study the effect of structure on crystallinity and processability. Both random and segmented copolymers containing different amounts of DHTP have been prepared via standard solution nucleophilic aromatic substitution polymerization technique. Only segmented polysulfone containing 50% BP and 50% DHTP was found to be semi-crystalline. This PAES had a melting temperature (Tm) 320°C in the first heating cycle of a DSC measurement and the presence of crystallites was confirmed by wide angle X-ray diffraction (WAXS).

Neutral and Cationic Cyclopentadienyliron Macromolecules Containing Azo Dyes

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Sulfonated poly(aryl ether ether ketone ketone)s containing fluorinated moieties as proton exchange membrane materials

AbstractA series of sulfonated poly(aryl ether ether ketone ketone)s statistical copolymers with high molecular weights were synthesized via an aromatic nucleophilic substitution polymerization. The sulfonation content (SC), defined as the number of sulfonic acid groups contained in an average repeat unit, could be controlled by the feed ratios of monomers. Flexible and strong membranes in sodium sulfonate form could be prepared by the solution casting method, and readily transformed to their proton forms by treating them in 2 N sulfuric acid. The polymers showed high Tgs, which increased with an increase in SC. Membranes prepared from the present sulfonated poly(ether ether ketone ketone) copolymers containing the hexafluoroisopropylidene moiety (SPEEKK‐6F) and copolymers containing the pendant 3,5‐ditrifluoromethylphenyl moiety (SPEEKK‐6FP) had lower water uptakes and lower swelling ratios in comparison with previously prepared copolymers containing 6F units. All of the polymers possessed proton conductivities higher than 1 × 10−2 S/cm at room temperature, and proton conductivity values of several polymers were comparable to that of Nafion at high relative humidity. Their thermal stability, oxidative stability, and mechanical properties were also evaluated. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2299–2310, 2006

Poly(aryl ether sulfide)s by sulfide-activated nucleophilic aromatic substitution polymerization

Poly(aryl ether sulfide)s have been produced by nucleophilic aromatic substitution with phenoxide nucleophiles bisphenol A and bisphenol AF, and the activated arylfluorides bis(4-fluorophenyl)sulfide and 2,7-difluorothianthrene. The resulting polymers are thermally stable, amorphous materials that have been characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and gel permeation chromatography (GPC). Moderate molecular weights have been achieved, representative of greater than 98% conversion of arylfluorides. The poly(aryl ether thianthrene)s are flame resistant and self extinguish within 0.2 s upon removal from a flame source. TGA of the poly(aryl ether thianthrene)s in an inert atmosphere result in a char yield greater than 50% at 750 °C. The flame resistant properties are more effectively modeled by TGA in an inert atmosphere as compared to TGA in an air atmosphere. The poly(aryl ether thianthrene)s are found to have high refractive index values, 1.61–1.70, depending on wavelength and bisphenol composition.

Fluorenyl-containing sulfonated poly(aryl ether ether ketone ketone)s (SPFEEKK) for fuel cell applications

A series of fluorenyl-containing sulfonated poly(aryl ether ether ketone ketone)s (SPFEEKK) were synthesized via aromatic nucleophilic substitution polymerization. The sulfonation content (SC) was controlled by the feed ratios of sulfonated and nonsulfonated monomers. Flexible and strong membranes in the sulfonic acid form were obtained from cast membranes in the sodium salt forms by treatment with acid. The thermal properties, water uptake, swelling ratio, water state, oxidative stability, proton conductivity and methanol permeability were investigated. All the polymers had proton conductivities greater than 1 × 10 −2 S/cm at room temperature, and the conductivity values of m-SPFEEKK-80 and p-SPFEEKK-80 were up to 1.86 × 10 −1 and 1.78 × 10 −1 S/cm at 100 °C. This series of polymers also possessed good dimensional stability in water and low methanol crossover.