Thianthrene as an activating group for the synthesis of poly(aryl ether thianthrene)s by nucleophilic aromatic substitution

A method for the preparation of poly(aryl ether thianthrene)s has been developed in which the aryl ether linkage is generated in the polymer‐forming reaction. The thianthrene heterocycle is sufficiently electron‐withdrawing to allow fluoro displacement with phenoxides by nucleophilic aromatic substitution. The monomer for this reaction, 2,7‐difluorothianthrene, can be synthesized in a moderate yield by a simple reaction sequence. Semiempirical calculations at the PM3 level suggest that 2,7‐difluorothianthrene is sufficiently activated, whereas NMR spectroscopy (¹H and ¹³C) indicates that the monomer is only slightly activated or (¹⁹F) not sufficiently activated for nucleophilic aromatic substitution. Model reactions with p‐cresol have demonstrated that the fluorine atoms on 2,7‐difluorothianthrene are readily displaced by phenoxides in high yields, and the process has been deemed suitable for polymer‐forming reactions. High‐molecular‐weight polymers have been produced from bisphenol A, bisphenol AF, and 4,4′‐biphenol. The polymers have been characterized with gel permeation chromatography, NMR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. The glass‐transition temperatures for the polymers of different compositions and molecular weights range from 138 to 181 °C, and all the polymers have shown high thermooxidative stability, with 5% weight loss values in an air environment approaching 500 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6353–6363, 2004     

Phthalide as an activating group for the synthesis of poly(aryl ether phthalide)s by nucleophilic aromatic substitution

The phthalide ring was examined as an activating group for nucleophilic aromatic substitution. The proposed mechanism by which activation occurs is through a ring opening of the phthalide ring to form a Meisenheimer‐like σ complex. 3,3‐Bis(4‐fluorophenyl)phthalide was synthesized and examined under different reaction conditions to determine its suitability for polymer formation. Semiempirical calculations at the PM3 level suggested that 3,3‐bis(4‐fluorophenyl)phthalide is only moderately activated, whereas ¹H, ¹³C, and ¹⁹F NMR spectroscopy suggested that the monomer was not sufficiently activated for nucleophilic aromatic substitution. However, low‐molecular‐weight polymers (number‐average molecular weight < 7000 g/mol) were produced from bisphenol A, hydroquinone, and phenolphthalein. The polymers were characterized by gel permeation chromatography, matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry, NMR spectroscopy, and differential scanning calorimetry. The polymers displayed relatively high glass‐transition temperatures. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3046–3054, 2002     

Synthesis of triarylamine‐containing poly(arylene ether)s by nucleophilic aromatic substitution reaction

We report synthesis of a series of new triarylamine‐containing AB‐type monomers and their polymers via nucleophilic aromatic substitution (S_NAr) reaction. Monomers consisting of a hydroxyl group at the para position of the nitrogen group in one phenyl ring and a fluorine leaving group at the para position in another phenyl ring were synthesized via palladium‐catalyzed amination reaction. The fluorine leaving group was activated by trifluoromethyl group at the ortho position and an electron‐withdrawing group (EWG) introduced at the para position of the unsubstituted phenyl ring that enabled control over monomer reactivity. S_NAr reaction of the monomers successfully produced corresponding poly(arylene ether)s with pendant EWGs that exhibited good solubility and thermal stability. Optical and electrochemical properties of the polymers were also affected by incorporation of EWGs. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2692‐2702     

Poly(arylene sulfide)s via nucleophilic aromatic substitution reactions of halogenated pyromellitic diimides

Nucleophilic aromatic substitution (SNAr) reactions are exploited to prepare poly(arylene sulfide)s (PAS's) via the reaction of bis-thiolates and dibrominated pyromellitic diimide (PMDI) derivatives. Small-molecule model studies reveal the reaction is well-defined and proceeds in quantitative yield in practical times at room temperature. Variation in comonomer feed ratios allowed some control over target polymer molecular weights in the step polymerization, but control was likely limited by the relatively poor polymer solubility in the dipolar aprotic solvents typically employed to promote SNAr reactions. One substitution pattern produces a steric “pocket” around the PMDI units, inducing a peculiar solubility trend in halogenated solvents; that is, greatly reduced solubility in CHCl₃ relative to CH₂Cl₂ and C₂H₂Cl₄. One example small-molecule readily dissolves in CHCl₃ at room temperature, then rapidly grows poorly soluble crystals revealed by single-crystal XRD to contain CHCl₃ molecules in the steric pockets. Finally, the recently demonstrated depolymerization of phthalonitrile-based PAS's via ipso substitution with monothiolates as chain scission agents yields quantitative molecular weight reduction to monomeric species from the polymers reported here.     

Preparation of poly(ether ketone)s derived from 2,5‐furandicarboxylic acid via nucleophilic aromatic substitution polymerization

From the viewpoint of the suppression of the petroleum consumption, aromatic poly(ether ketone)s (PEKs) were prepared by the nucleophilic aromatic substitution polymerization of 2,5‐bis(4‐fluorobenzoyl)furan (BFBF) synthesized from biomass and aromatic bisphenols. The model reaction of BFBF and p‐methoxyphenol revealed that BFBF possessed enough reactivity for the nucleophilic aromatic substitution reactions. The polymerizations of BFBF and aromatic bisphenols afforded high molecular weight polymers with good yields in N‐methylpyrrolidone and diphenyl sulfone for several hours. The longer polymerization time brought about the formation of insoluble parts in any solvents and reduction of molecular weight. The obtained PEKs were thermoplastics and exhibited good thermal stability, mechanical properties, and chemical resistance comparable to common high‐performance polymers. The thermal properties were tunable with the structure of bisphenols. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3094–3101     

Fluoride‐terminated hyperbranched poly(arylene ether phosphine oxide)s via nucleophilic aromatic substitution

A series of AB_x‐type triarylphosphine oxide monomers, bis‐(4‐fluorophenyl)‐(4‐hydroxyphenyl)phosphine oxide ( 4a ), bis‐(3,4‐difluorophenyl)‐(4‐hydroxyphenyl)phosphine oxide ( 4b ), and 4‐hydroxyphenyl‐bis‐(3,4,5‐trifluorophenyl)phosphine oxide ( 4c ) were prepared, characterized, and polymerized under nucleophilic aromatic substitution conditions [N‐methylpyrrolidone (NMP), K₂CO₃] to provide the corresponding hyperbranched poly(arylene ether phosphine oxide)s with number‐average molecular weights ranging from 9200 to 14,600 Da. NMR spectroscopic analysis indicated the presence of highly branched products with an approximate degree of branching of 0.57. The polymers were soluble in a variety of typical organic solvents and displayed excellent thermal stability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1456–1467, 2002     

Poly(arylene thioether) synthesis via nitro‐displacement reaction

High molecular weight poly(arylene thioether)s containing trifluoromethyl groups were prepared through the aromatic nucleophilic nitro‐displacement reaction of a dinitro monomer with aromatic dithiols. The high reactivity of the monomer, 4,4′‐dinitro‐3,3′‐bis(trifluoromethyl)biphenyl(1), activated by o‐trifluoromethyl groups and complete exclusion of oxygen was critical for the successful polymerization without any disulfide formation. The resulting trifluoromethylated poly(arylene thioether)s ( P1 and P2 ) were amorphous, dissolved in common organic solvents, and showed superior thermal properties compared to commercial poly(phenylene sulfide). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2440–2447, 2006     

Novel heterocyclic poly(arylene ether ketone)s: Synthesis and polymerization of 4‐(4′‐hydroxyaryl)(2H)phthalazin‐1‐ones with methyl groups

Based on green chemistry, a simple and efficient direct synthesis of 4‐(4′‐hydroxyaryl)(2H)phthalazin‐1‐ones ( 2a–2f ) was developed in a two‐step reaction, in which the Friedel–Crafts acylation reaction of six phenols with phthalic anhydride was initially carried out and then followed by cyclization with hydrazine hydrate in good to excellent yields with high regioselectivity. A number of novel heterocyclic poly(arylene ether ketone)s were prepared conveniently from several unsymmetrical, twist, and noncoplanar phthalazinone‐containing monomers ( 2a–2f ) and an activated difluoro monomer via a N? C coupling reaction. It was very interesting that the obtained monomers and polymers exhibited diverse properties with the variation of the number and location of the substituted methyl groups. All these polymers had a high molecular weight with M_n and η_inh in the range of 44,960–169,000 Da and 0.38–0.79 dL/g, respectively. Actually, the obtained polymers displayed excellent thermal properties with T_g's ranging from 222 to 248 °C and 5% weight loss temperatures in nitrogen higher than 430 °C. Moreover, these polymers were readily soluble in common organic solvents, such as N‐methyl‐2‐pyrrolidone, chloroform, pyridine, and m‐cresol, and could be cast into flexible and colorless or nearly colorless films by spin‐coating or casting processes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1525–1535, 2007     

Synthesis,photoluminescence, and electrochromism of novel aromatic poly(amine‐1,3,4‐oxadiazole)s bearing anthrylamine chromophores

Two novel poly(amine‐hydrazide)s were prepared from the polycondensation reactions of the dicarboxylic acid, 9‐[N,N‐di(4‐carboxyphenyl)amino]anthracene ( 1 ), with terephthalic dihydrazide ( TPH ) and isophthalic dihydrazide ( IPH ) via the Yamazaki phosphorylation reaction, respectively. The poly(amine‐hydrazide)s were readily soluble in many common organic solvents and could be solution cast into transparent films. Differential scanning calorimetry (DSC) indicated that these hydrazide polymers had glass‐transition temperatures (T_g) in the range of 182–230 °C and could be thermally cyclodehydrated into the corresponding oxadiazole polymers in the range of 300–400 °C. The resulting poly(amine‐1,3,4‐oxadiazole)s had useful levels of thermal stability associated with high T_g (263–318 °C), 10% weight‐loss temperatures in excess of 500 °C, and char yield at 800 °C in nitrogen higher than 55%. These organo‐soluble anthrylamine‐based poly(amine‐hydrazide)s and poly (amine‐1,3,4‐oxadiazole)s exhibited maximum UV‐vis absorption at 346–349 and 379–388 nm in N‐methyl‐2‐pyrrolidone (NMP) solution, respectively. Their photoluminescence spectra in NMP solution showed maximum bands around 490–497 nm in the green region. The poly(amine‐hydrazide) I ‐ IPH showed a green photoluminescence at 490 nm with PL quantum yield of 29.9% and 17.0% in NMP solution and film state, respectively. The anthrylamine‐based poly(amine‐1,3,4‐oxadiazole)s revealed a electrochromic characteristics with changing color from the pale yellow neutral form to the red reduced form when scanning potentials negatively from 0.00 to ?2.20 V. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1584–1594, 2009     

Poly(arylene ether)s with pendant diphenyl phosphoryl groups: Synthesis,characterization, and thermal properties

A series of poly(arylene ether)s, (PAEs), carrying a pendant diphenyl phosphoryl group were prepared via the nucleophilic aromatic substitution (NAS) reactions of 3,5‐difluorotriphenylphosphine oxide, 6 . The difluoro monomer 6 was synthesized via two‐step reaction sequence and subsequently characterized by ¹H, ¹³C, ¹⁹F, and ³¹P NMR spectroscopy, GC/MS, and elemental analysis. The reactivity of the electrophilic sites in 6 , activated by only a diphenylphosphoryl group located in the meta‐position, in 6 was probed via NMR spectroscopy and model reactions and was determined to be sufficient to undergo typical NAS reactions. High molecular weight, amorphous, organic soluble poly(arylene ether)s, bearing a pendant diphenylphosphoryl group, were prepared via the reaction of 6 with a variety of bis‐phenols under typical NAS conditions. The poly(arylene ether)s were characterized for structure via the use of ¹H, ¹³C, and ³¹P NMR spectroscopy while their thermal properties were evaluated using DSC and TGA analysis. The glass transition temperatures (T_g) of the synthesized PAEs ranged from 143 to 175 °C, while their 5% weight loss temperatures ranged from 467 to 510 °C under nitrogen and from 470 to 526 °C in air. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

A series of new high‐performance materials based on poly[4′‐fluorophenyl‐bis(4‐phenyl)phosphine oxide]

A new series of high‐performance poly(arylene phosphine oxide) (PAPO) materials were synthesized postpolymerization from fluorinated poly(arylene phosphine oxide) (f‐PAPO). The new materials had increased solubility and film‐forming ability over the parent f‐PAPO. With the careful choice of the nucleophile, the thermal stability was also increased. The parent polymer f‐PAPO was synthesized via Ni(0) coupling from aromatic chloride and mesylate monomers. Both monomers were polymerized successfully to create polymers with intrinsic viscosities of 0.235 and 0.123 dL/g, respectively. The higher molecular weight f‐PAPO gave a glass transition of 320 °C and a char yield of 54% at 650 °C in air. The substitution of f‐PAPO via nucleophilic aromatic substitution produced PAPO thermoplastics with significant changes in the properties. The largest increase in the thermal stability relative to f‐PAPO was from 563 to 600 °C 10% weight‐loss values in nitrogen after the displacement of fluoride by 4‐aminophenol, which yielded poly[4‐(4‐aminopheonxyphenyl)bis(4′‐phenyl)phosphine oxide]. Additionally, the char yield increased from 54 to 71% in air at 650 °C. The solubility of the parent polymer was improved after substitution with 3‐tert‐butylphenol, n‐nonylamine, and poly(ethylene glycol)monomethyl ether. All of these became soluble in chloroform, N,N‐dimethylacetamide, and dimethyl sulfoxide. Copolymers were synthesized with 2,5‐dichloro‐4′‐fluorobenzophenone to improve the solubility of f‐PAPO without the loss of thermal stability. These copolymers also underwent nucleophilic aromatic substitution to create an epoxy cure agent that was used with the DEN 431 resin. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2277–2287, 2003     

Synthesis and properties of poly(arylene ether phenyl-s-triazine)s

A series of new poly(arylene ether phenyl-s-triazine)s was prepared by the nucleophilic aromatic substitution polymerization of the potassium salt of bisphenols with 2,4-bis (halophenyl)-6-phenyl-s-triazine in N-methyl-2-pyrrolidone at elevated temperature. The polymers with inherent viscosities exceeding 0.5 were obtained after polymerization for 1 h using 2,4-bis(fluorophenyl)-6-phenyl-s-triazine as a monomer. The glass transition temperatures of the resulting polymers ranged from 200 to 260°C depending on the bisphenol used in the polymer synthesis. The poly(arylene ether phenyl-s-triazine)s demonstrated excellent thermal stabilities in excess of 490°C (5% weight loss in air). The isothermal TGA measurements (400°C under air or nitrogen atmosphere) revealed that the 4,4'-biphenol- and hydroquinone-based poly(arylene ether phenyl-s-triazine)s belong to the most superior class of heat resistant polymers, such as polyimide Kapton?. The mechanical properties of these polymers are also described. © 1994 John Wiley & Sons, Inc.     

Synthesis and properties of poly(arylene ether imide ketone)s

Poly(arylene ether ketone)s containing imide units were prepared by the aromatic nucleophilic displacement reaction of the potassium salts of bisphenols with bis(4-fluorobenzoyl)phthalimides in N-methyl-2-pyrrolidone at elevated temperature. The polymers having inherent viscosities of 0.34–0.77 dL/g were obtained in 2 h. The polymers exhibited glass transition temperatures ranging from 216 to 268°C and decomposition temperatures (5% weight loss under air atmosphere) ranging from 450–570°C mainly depending on the bisphenols used in the polymer synthesis. The isothermal TGA measurements (400°C under air or nitrogen atmosphere) revealed that the 4,4'-biphenol- and hydroquinone-based poly(arylene ether ketone imide)s belong to a superior class of heat resistant polymers. The mechanical properties of these polymers are also described. © 1994 John Wiley & Sons, Inc.     

Catalytic [2 + 2 + 2] cycloaddition polymerization of diyne–nitrile monomers in the presence of CoCl2‐6H2O/diphosphine/Zn

Cobalt‐catalyzed [2 + 2 + 2] cocycloaddition reaction of 1,6‐diynes and nitriles to generate substituted pyridines has been applied to the polymerization of diyne–nitrile monomers, the reaction of which proceeded smoothly in a step‐growth fashion to provide linear polymers comprising pyridine structures in the main chain. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 345–351     

Synthesis of highly refractive and transparent polyimides derived from 4,4′‐thiobis[2″,6″‐dimethyl‐4″‐(p‐phenylenesulfanyl)aniline]

New sulfur‐containing aromatic diamines with methyl groups at the ortho position of amino groups have been developed to prepare highly refractive and transparent aromatic polyimides (PIs) in the visible region. All aromatic PIs derived from 4,4′‐thiobis[2″‐methyl‐4″‐(p‐phenylenesulfanyl)aniline ( 2 ), 4,4′‐thiobis[2,″6″‐dimethyl‐4″‐(p‐phenylenesulfanyl)aniline ( 5 ), and aromatic dianhydride, 4,4′‐[p‐thiobis(phenylenesulfanyl)]diphthalic anhydride ( 6 ) were prepared via a two‐step polycondensation. All PIs showed good thermal properties, such as 10% weight loss temperature in the range of 497–500 °C and glass transition temperatures above 196 °C. In addition, the PIs showed good optical properties, such as optical transparency above 75% at 450 nm with a 10‐μm film thickness, high refractive indices ranging from 1.7135 to 1.7301, and small in‐plane/out‐of‐plane birefringences between 0.0066 and 0.0076. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 656–662, 2010     

9,9‐Diaryl‐4,5‐diazafluorene‐based Cardo polymer; Synthesis and characteristic properties

To open out new aspects of 9,9‐diarylfluorene (DAF)‐based polymers with high performances, 9,9‐(4‐hydroxyphenyl)‐4,5‐diazafluorene ( N‐BPF ) was designed as a new cardo structure and the properties of poly(ether ketone)s ( N‐PEKs ) containing N‐BPF skeletons were examined in detail. N‐PEKs were synthesized in high yields via polycondensation of N‐BPF with difluoroarenes. N‐PEKs showed cardo polymer‐specific properties such as high thermal stability and high solubility in organic solvents. The addition of p‐toluenesulfonic acid (TsOH) to N‐PEK resulted in the formation of network polymer based on interchain hydrogen bonds. It turned out that the films of network polymer are flexible and transparent and exhibit high refractive index and low birefringence. The effects of feed ratio of TsOH to N‐PEK were also evaluated on the mechanical properties of network polymer. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4541–4549     

Poly(ether sulfone)s using a rigid dibenzothiophene dioxide heterocycle

Poly(aryl ether)s were prepared by nucleophilic aromatic substitution using conformationally restricted dichloro‐ and difluorodibenzothiophene dioxide heterocyclic monomers with bisphenol A or bisphenol AF. The heterocyclic monomers were prepared from the bis(4‐halophenyl) sulfones in two steps via lithiation followed by copper catalyzed intramolecular coupling and characterized by ¹H, ¹³C, ¹⁹F NMR spectroscopy and GC/MS. Reactivity of the fluorine containing monomer was examined using semi‐empirical methods and NMR spectroscopy measurements and found to be potentially more reactive than bis(4‐fluorophenyl) sulfone, even with a conformationally locked sulfone as the electron withdrawing group. Successful polymerizations of both the fluorine and chlorine containing monomers with bisphenol A and bisphenol AF nucleophiles were accomplished, providing polymers with number average molecular weights of approximately 45 kg/mol (difluoro monomer) and 10–20 kg/mol (dichloro monomer). The polymers exhibited high T_gs ranging from 238 to 256 °C and displayed good thermal stability with 5% degradation temperatures in air from 453–510 °C, depending on molecular weight and bisphenol composition. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3127–3131     

Poly(paraphenylene sulfide) and Poly(metaphenylene sulfide) via Light‐Initiated SRN1‐Type Polymerization of Halogenated Thiophenols

In this work, the synthesis of various halogenated thiophenol derivatives is presented. These thiophenols are used as monomers in light‐initiated S_RN1‐type radical polymerization reactions. The method provides easy access to industrially relevant poly(paraphenylene sulfide) and poly(metaphenylene sulfide). The influence of the halide leaving group and of other substituents in the thiophenol monomer on the polymerization process is investigated.

     

Synthesis of poly(arylene thioether)s from protected dithiols and aromatic difluorides with an organic base

Aromatic poly(arylene thioether)s were synthesized from N‐propyl‐S‐carbamate‐protected aromatic dithiols and aromatic difluorides. The deprotection of the protected dithiols with an organic base such as 1,8‐diazabicyclo[5.4.0]‐7‐undecene at room temperature and subsequent polymerization with the difluoride monomers at 120 °C in N‐methyl‐2‐pyrrolidinone produced high molecular weight polymers with intrinsic viscosities as high as 0.45 dL/g. The use of organic bases instead of inorganic bases for the generation of thiophenoxide nucleophile was a convenient way of avoiding metallic impurities in the synthesis of the poly(arylene thioether)s through a nucleophilic aromatic substitution reaction. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2021–2027, 2005