Aromatic Polyketones Research Articles

Alternating copolymerization of carbon monoxide and vinyl arenes using [N,N] bidentate palladium catalysts

AbstractThe alternating copolymers of carbon monoxide (CO) and vinyl arene monomers, namely aromatic polyketones, are a family of attractive engineering plastic. In the catalytic synthesis of this kind of polymeric materials, [N,N] bidentate palladium catalysts represent the most successful catalytic systems. In this review, we introduce the present status of polyketone synthesis, with a focus on the aromatic polyketones made from vinyl arene and CO. We also address the palladium‐catalyzed CO/vinyl arene alternating copolymerization mechanism. A variety of [N,N] bidentate palladium catalysts bearing 2,2′‐bipyridine, 1,10‐phenanthroline, α‐diimine, and pyridine‐imine ligands are surveyed for CO/vinyl arene copolymerization. The effects of vinyl arene monomer, counteranion, and solvent on copolymerization are also discussed. The copolymerization stereochemistry including chain end‐control and enantiomorphic site control mechanisms is introduced. This review aims to promote the design of [N,N] bidentate palladium catalysts for CO/vinyl arene copolymerization for the development of high‐performance aromatic polyketones.

Synthesis and characterization of bio-based aromatic polyketones and polyetherketones derived from divanillic acid

Bio-based aromatic polyketones (PKs) and polyetherketones (PEKs) were synthesized by the electrophilic substitution reaction of alkoxylated divanillic acid (R-DVA) and 2,2′-dimethoxybiphenyl or diphenylether. Alkoxy side-chains were introduced at the hydroxyl groups of DVA prior to polymerization. Polymerizations were carried out in a phosphorus pentoxide (P2O5)/methanesulfonic acid (MsOH) system. DVA-based PKs and PEKs were soluble in common organic solvents including chloroform and dimethylsulfoxide, and their chemical structures were determined by 1H and 13C NMR. The weight-average molecular weights (Mw) of the PKs were 2.6–15.0 × 103 g/mol, and those of all PEKs were approximately 1.0 × 103. The 10% degradation temperatures of the PKs and PEKs were 340–400 °C. Dynamic mechanical analysis showed that the PKs and PEKs were amorphous. The PKs with methyl to butyl side-chains exhibited high glass transition temperatures (Tg) in the range 250–297 °C, while Tg of PK (octyl side-chain) was 157 °C and those of the PEKs were 73–127 °C.

Synthesis of thermally robust benzimidazolone-based wholly aromatic polyketones.

A series of wholly aromatic polyketones bearing benzimidazolone moieties (PK-BI) were synthesized via N–C coupling polycondensation. Calcium carbonate coupled with potassium carbonate was used for the first time to achieve a high molecular weight, with Tg of the polymer as high as 299 °C. The polymer structure was confirmed by solid state 13C NMR and FT-IR. The thermal stability of wholly aromatic polyketones with a benzimidazolone unit in the main chain was significantly improved, being higher than those of PEEKs and other amorphous PAEKs, proved by thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) analysis. The degradation activation energy (Ek) values estimated by Flynn–Wall–Ozawa (FWO) and Kissinger methods were 260.33 kJ mol−1 and 282.57 kJ mol−1, respectively, which are higher than those of PEEKs.

Synthesis, Optical and Electrochemical Properties of High-Quality Cross-Conjugated Aromatic Polyketones.

This paper describes the synthesis and characterization of three new aromatic polyketones with repeating units based on 2,2′-(2,5-dihexyl-1,4-phenylene) dithiophene (PTK), 2,2′-(9,9-dihexyl-9H-fluorene-2,7-diyl)dithiophene (PFTK), and 4,7-bis(3-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole (PBTK). These polymers were obtained with a one-pot Suzuki–Miyaura cross-coupling-promoted homopolymerization to afford high-quality, defect-free polymers. Experimental and theoretical studies were applied to investigate their optical and electrical properties. The cross-conjugated nature of aromatic polyketones imparts excellent thermal stability. Exposure to acid converts the cross-conjugation to linear-conjugation, enabling the dynamic tuning of optoelectronic properties.

Synthesis of aromatic polyketones by nonstoichiometric Friedel–Crafts polycondensation using AlCl3

Aromatic polyketones were successfully synthesized by Friedel–Crafts acylation using AlCl3 between aromatic dicarboxylic acid chlorides and 2,2′-dimethoxybiphenyl under both stoichiometric and nonstoichiometric conditions.

Totally Organic Redox-Active pH-Sensitive Nanoparticles Stabilized by Amphiphilic Aromatic Polyketones.

Amphiphilic aromatic polymers have been synthesized by grafting aliphatic polyketones with 4-(aminomethyl)benzoic acid at different molar ratios via the Paal-Knorr reaction. The resulting polymers, showing diketone conversion degree of 16%, 37%, 53%, and 69%, have been complexed with the redox-active 2,3,5-triphenyl-2H-tetrazolium chloride, a precursor molecule with which aromatic-aromatic interactions are held. Upon addition of ascorbic acid to the complexes, in situ reduction of the tetrazolium salt produced 1,3,5-triphenylformazan nanoparticles stabilized by the amphiphilic polymers. The stabilized nanoparticles display highly negative zeta potential [-(35-70) mV] and hydrodynamic diameters in the submicron range (100-400 nm). Nonaromatic polyelectrolytes or hydrophilic aromatic copolymers showing low linear aromatic density and high linear charge density such as acrylate/maleate and sulfonate/maleate-containing polymers were unable to stabilize formazan nanoparticles synthesized by the same method. The copolymers studied here bear uncharged nonaromatic comonomers (unreacted diketone units) as well as charged aromatic comonomers, which furnish amphiphilia. Thus, the linear aromatic density and the maximum linear charge density have the same value for each copolymer, and the hydrophilic/hydrophobic balance varies with the diketone conversion degree. The amphiphilia of the copolymers allows the stabilization of the nanoparticles, even with the copolymers showing a low linear aromatic density. The method of nanoparticle synthesis constitutes a simple, cheap, and green method for the production of switchable totally organic, redox-active, pH-sensitive nanoparticles that can be reversibly turned into macroprecipitates upon pH changing.

Nonstoichiometric polycondensation based on Friedel–Crafts acylation in superacids for the syntheses of aromatic polyketones

Based on Friedel–Crafts acylation, nonstoichiometric polycondensation was achieved using 4,4′-dicarboxydiphenyl ether and 2,2′-dimethoxybiphenyl in trifluoromethanesulfonic acid.

Cross-Conjugated n-Dopable Aromatic Polyketone

This paper describes the synthesis and characterization of a high molecular weight cross-conjugated polyketone synthesized via scalable Friedel–Crafts chemistry. Cross-conjugated polyketones are precursors to conjugated polyions; they become orders of magnitude more conductive after a two-electron reduction and demonstrate reversible spinless doping upon protonation with acids. Cross-conjugated polyketones are a new polymer platform that possess the same optoelectronic tunability as conventional polymers but with excellent thermal and oxidative stability. We constructed a proof-of-concept organic light-emitting diode device and demonstrate that a cross-conjugated polyketone can be successfully used as an n-dopable semiconducting material.

Synthesis of organosoluble and fluorescent aromatic polyketones bearing 1,1′-binaphthyl units through Suzuki–Miyaura coupling polymerization

Nanosized palladium cluster-catalyzed Suzuki–Miyaura coupling polymerization of 1,1′-binaphthyldiyl-bearing diiodides with expanded π-conjugated aromatic diboronic acid pinacol diesters affords aromatic polyketones, which have blue-emitting fluorescent properties (λ em 450–489 nm) in addition to high thermal stability (T g 190–297 °C) and excellent solubility in common organic solvents such as DMSO and NMP.

Synthesis of water-soluble wholly aromatic polyketones bearing 1,1′-binaphthyl-6,6′-diyl units

A water-soluble wholly aromatic polyketone modified with sodium carboxylate (PK-COONa) was synthesized through demethylation of the wholly aromatic polyketone bearing four methoxy groups per repeat unit (PK-OMe) followed by ethoxycarbonylmethylation and saponification. The obtained polyketones, i.e., the methyl-cleaved analogue (PK-OH), the ethoxy carbonyl group-bearing analogue (PK-COOEt), the sodium carboxylate analogue (PK-COONa), and the carboxy group-bearing analogue (PK-COOH), have varying solubilities in water and common organic solvents and thermal stabilities, depending on the functional groups.

Synthesis of thermally stable, wholly aromatic polyketones with 2,2′-dimethoxy-1,1′-binaphthyl-6,6′-diyl units through nanosized-palladium-cluster-catalyzed Suzuki–Miyaura coupling polymerization

Wholly aromatic polyketones with 2,2′-dimethoxy-1,1′-binaphthyl-6,6′-diyl units in the main chains were synthesized through Suzuki–Miyaura coupling polymerization catalyzed by nanosized palladium clusters, which were easily prepared from Pd(OAc)2, PPh3, K2CO3, and Bu4NOAc in 1,4-dioxane. The resulting polyketones have both high thermal stability (high Tg) and solubility in common organic solvents, such as CHCl3 and N,N-dimethylformamide (DMF). Flexible and pale brown films were obtained by casting from a CHCl3 solution.

Synthesis, characterization and biological activity of polyketones

Polyketone resins have been prepared by the Friedel-Crafts polymerization of dithiophenylidenecyclopentanone (I), dithiophenylidenecyclohexanone (II) and dithiophenylideneacetone (III) with adipoyl, sebacoyl and terephthaloyl dichlorides using boron trifluoride as catalyst and carbon disulphide as solvent. Polymers were characterized with IR, 1H-NMR, and the results showed the presence of carbonyl of ketonic groups in the main chain. The polyketones have inherent viscosities of 0.40–0.70 dL/g. All the polymers are semicrystalline and most of them are partially soluble in most common organic solvents but freely soluble in aprotic solvents. The temperatures of 50% weight loss are as high as 185°C to 280°C in air, indicating that these aromatic polyketones have excellent thermal stability. All the polyketones were tested for their antimicrobial activity against bacteria and fungi.

Novel aromatic proton-exchange polyelectrolytes via polyacylation of pre-sulfonated monomers

Disodium 2,2′-di(sulfopropyloxy)-biphenyl as a novel sulfonated aromatic diarene monomer has been facilely synthesised via one-step etherification in high yield and successfully applied in polyacylation under mild conditions for the first time. Proton-exchange membranes of the resulting side-chain-type sulfonated aromatic polyketones exhibit proton conductivity higher than Nafion® while maintaining a low swelling ratio, which may be ascribed to the microstructure of Nafion-like ionic clusters as observed by atomic force spectrometry. This work demonstrates that polyacylation directly from pre-ionised monomers offers a novel and powerful tool to advanced aromatic proton-exchange polyelectrolytes for fuel cells.

Synthesis of Aromatic Polyketones Bearing 1,1′-Binaphthyl-2,2′-dioxy Units through Suzuki–Miyaura Coupling Polymerization

Abstract Palladium nanocluster-catalyzed Suzuki–Miyaura coupling polymerization of 2,2′-bis(iodobenzoylphenoxy)-1,1′-binaphthyls 2 with aromatic diboric acid diesters 3 proceeded smoothly, affording 1,1′-binaphthyl-2,2′-dioxy-bearing aromatic polyketones 4. The resulting polyketones 4 have excellent thermal stability and solubility in typical organic solvents.

Synthesis of Wholly Aromatic Polyketones

The structural design strategy and the synthetic approaches for the wholly aromatic polyketones and the monomers are described. Electrophilic aromatic aroylation substitution polycondensation and aromatic coupling polycondensation have been investigated as synthetic routes for wholly aromatic polyketones by the author's group. Acyl-acceptant arene molecules as the electrophilic aromatic aroylation substitution polycondensation type monomers and the aromatic nuclei for bis(chlorobenzoylated) compounds as the aromatic coupling polycondensation one were designed and synthesized employing 2,2′-dioxybiphenyl, 2,2′-dioxy-1,1-binaphtyl, and o-terphenyl skeletons. Determining factors for monomers, which enable regioselective polycondensation, are also discussed. The properties of polyketones are also discussed briefly on the basis of polymer repeating unit structures.

Synthesis, Characterization and Antimicrobial Activity of New 1,2,3-Selenadiazoles

The commercially available aromatic polyketones 1a-d were utilized for the synthesis of the multi-arm1,2,3-selenadiazole derivatives 3a-d. The preparation starts with the reaction between compounds 1a-d and p-toluenesulfonyl hydrazide to give the corresponding tosylhydrazones 2a-d. Subsequent reaction with selenium dioxide leads to regiospecific ring closure of the tosylhydrazones to give the target multi-arm 1,2,3-selenadiazole derivatives in high yield. A 1,2,3-selenadiazole derivative 3e containing an epoxide ring was also prepared. The structures of all the synthesized compounds were confirmed on the basis of spectral and analytical data. The compounds were screened in vitro for their antimicrobial activity against various pathogenic bacterial and Candida strains obtained from King Abdullah Hospital in Irbid -Jordan. Compounds 3a, 3c and 3e were found to be highly active against all the selected pathogens. Compound 3e showed an inhibition zone of 13 mm against the highly resistant P. aruginosa.

TfOH-mediated electrophilic aromatic aroylation polycondensation of 2,2′-bis[4-(trifluoromethylated aroyl)phenoxy]biphenyls with arenedicarbonyl dichlorides

CF 3-bearing wholly aromatic polyketones were prepared via trifluoromethanesulfonic acid (TfOH)-mediated electrophilic aromatic aroylation polycondensation of CF 3-bearing 2,2′-diaryloxybiphenyls with arenedicarbonyl dichlorides. 2,2′-bis[4-(4-trifluoromethylbenzoyl)phenoxy]biphenyl has good polymerizability and high adaptability against several arenedicarbonyl dichlorides. Against acyl-acceptant monomer having relatively small content of CF 3 group, AlCl 3 is also efficient acidic mediator in the condensation polymerization. The characteristic dependence of polymerizability and polymer property upon the number and position of CF 3 groups, the length of the side chains, and the kind of the arenedicarbonyl residues are also discussed.

Electrophilic aromatic aroylation polycondensation synthesis of wholly aromatic polyketone composed of 2,2′-dimethoxy-1,1′-binaphthylylene moiety

A wholly aromatic polyketone containing 2,2′-dimethoxy-1,1′-binaphthylylene moiety was successfully synthesized via electrophilic aromatic aroylation polycondensation with the aid of trifluoromethanesulfonic acid (TfOH) or phosphorus(V) oxide–methanesulfonic acid mixture (P 2O 5–MsOH). The polycondensation reactions employing two sets of monomers of opposite combination that should afford the same structure of repeating unit showed distinct results. The polycondensation employing 2,2′-dimethoxy-1,1′-binaphthyl ( 4) as the acyl-acceptant monomer proceeded to give medium-molecular-weight polymer. The polymer synthesis via transformation of biaryl 4 into the corresponding acyl-donor monomer 12 followed by polycondensation with 2,2′-dimethoxybiphenyl ( 1) predominated the procedure of direct usage of biaryl 4 as the acyl-acceptant monomer. Acyl-acceptant monomer has been demonstrated to play a more crucial role in determination of polymerizability than acyl-donor one.

Synthesis of Wholly Aromatic Polyketones Containing Optically Active Macrocycles

Wholly aromatic polyketones 7 containing bisbinaphthyl macrocycles were synthesized via P2O5-MsOH mediated direct condensation reaction of compound 3 with chlorobenzoic acids 4, nucleophilic aromatic substitution reaction of the resulting binaphthyl (5) with (S)-BINOL (1) in DMF/toluene, and NiBr2/Zn mediated aromatic coupling polymerization. The resulting polyketones 7 have excellent thermal resistance and solubility to organic solvents. Cyclic monomers 6 and polymers 7 have higher molar rotations based on optically active cyclic structures than pre-cyclized compounds 5.

Synthesis and chemical properties of new soluble aromatic polyketones with cross π-conjugated systems

New phosphorescent aromatic polyketones with a 9,9-dioctylfluorene copolymerizing unit ( ▪; Ar = p-phenylene (Polymer 1) or pyridine-2,5-diyl (Polymer 2); Flu = 9,9-dioctylfluorene-2,7-diyl) were prepared by organometallic polycondensation. Chemical properties of the polymers support a notion that the polymer has an expanded π-conjugated system through the cross π-conjugated –Ar–CO–Ar– unit. Polymer 1 was photoluminescent with an emission peak at about 430 nm and quantum yields of 10 and 21% at room temperature (r.t.) and 77 K, respectively. The light emission from Polymer 1 showed features of phosphorescence with long decay lifetimes of 0.22 and 0.53 s at r.t. and 77 K, respectively. Polymer 2 behaved similarly in light emission.