Rhodium-catalyzed substitution reaction of aryl fluorides with disulfides: p-orientation in the polyarylthiolation of polyfluorobenzenes

In the presence of a catalytic amount of RhH(PPh3)4 and 1,2-bis(diphenylphosphino)benzene, an aromatic fluoride, an organic disulfide (0.5 equiv), and triphenylphosphine (0.5 equiv) reacted in refluxing chlorobenzene to give an aryl sulfide in high yield. Since triphenylphosphine trapped fluoride atoms forming phosphine difluoride, both organothio groups of the disulfide reacted effectively, and the fluoride substituent reacted more readily than the chloride and bromide. The reaction of hexafluorobenzene and a diaryl disulfide gave 1,4-diarylthio-2,3,5,6-tetrafluorobenzene, 1,2,4,5-tetraarylthio-3,6-difluorobenzene, and hexaarylthiobenzene in a stepwise manner; pentafluorobenzene gave 1-arylthio-2,3,5,6-tetrafluorobenzene; 1,2,3,4-tetrafluorobenzene gave 1,2-diarylthio-3,6-difluorobenzene; and 1,2,4,5-tetrafluorobenzene gave 1,4-diarylthio-2-5-difluorobenzene. The polyarylthiolation reaction of polyfluorobenzenes exhibited a strong tendency to form 1,4-difluorobenzenes.     

Synthesis of perfluoro[2.2]paracyclophane

A synthesis of perfluoro[2.2]paracyclophane has been sought ever since the partially fluorinated octafluoro[2.2]paracyclophane (AF4) was prepared and its chemistry studied. This compound has now been prepared in 39% yield from the precursor, 1,4-bis(chlorodifluoromethyl)-2,3,5,6-tetrafluorobenzene by its reaction with Zn when heated in acetonitrile at 100 degrees C. Two preparations of the precursor, first from 1,4-dicyano-2,3,5,6-tetrachlorobenzene and an improved method beginning from 1,2,4,5-tetrachlorobenzene, are also described as are key comparisons to our related synthesis of AF4.     

Synthesis and characterization of polycarbonates based on bisphenol S by melt transesterification

Several sulfone-containing polycarbonates, having inherent viscosity 0.25–0.30 dL g⁻¹ in N,N-dimethylformamide (DMF), were prepared by melt polycondensation of diphenyl carbonate (DPC) with various aromatic and aliphatic diols, in the presence of zinc acetate as transesterification catalyst. The polycarbonates were examined with IR spectra, inherent viscosity, solubility, tensile strength, contact angle, DSC and TGA. Almost all polymers were soluble in DMF, pyridine, N-methyl pyrrolidinone (NMP), THF, phenol and dimethylsulfoxide (DMSO), partially soluble in nitrobenzene, but insoluble in acetone. Polycarbonate with introduced ether linkages leads to enhanced flexibility and elongation strength. The contact angle of the polycarbonate based on bisphenol S was found in the range 42–80°, smaller than that of polycarbonates based on bisphenol AF and bisphenol A. The wettability of polycarbonate films based on bisphenol S remarkably increased with increasing oxyethylene unit in polymer chain. The smaller values of T_d of PC-3-PC-7 than of PC-1 is attributed to the flexible ether linkage. The thermal stability of a brominated aromatic polycarbonate (PC-2) is less than that of the unbrominated one (PC-1). The brominated aromatic polycarbonate (PC-2) has good flame retardency, as indicated by the large limiting oxygen index 56. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2453–2460, 1997     

Preparation and properties of polyesters derived from 4,4′-sulfonyl dibenzoyl chloride by solution polycondensation

Sulfone-containing polyesters of 18 kinds having inherent viscosities of 1.19–0.16 dL g⁻¹ were prepared derived from 4,4′-sulfonyl dibenzoyl chloride by solution polycondensation from various aromatic and aliphatic diols in nitrobenzene at 82°C. The polyesters were examined with IR spectra, inherent viscosity, x-ray diffraction, solubility, DSC, and TGA. Polyester (PE-7) with the greatest inherent viscosity may reflect that bisphenol A having a electron-releasing group increases nucleophilic properties of the phenolate anion. Diols such as bisphenol AF (PE-13) and brominated diols (PE-4, PE-10, and PE-16) gave less favorable results. The diffractograms showed that all polyesters were essentially amorphous except that obtained from bisphenol S and its derivatives. Almost all polyesters except PE-1 and PE-2 were soluble in DMF, THF, tetrachloroethane and phenol/sym-tetrachloroethane (60/40 by mass) but insoluble in typical organic solvents such as acetone, toluene, and chloroform. These polymers obtained from aromatic bisphenols lost no mass below 309°C, but 10% loss of mass was recorded above 380°C in nitrogen. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of polyamides containing heterocyclic thiaxanthone units

Novel polyamides containing heterocyclic thiaxanthone units were prepared by condensing 2,7-dichloroformylthiaxanthone-5,5′-dioxide and 2,8-dichloroformylthiaxanthone-5,5′-dioxide with various aromatic diamines, under low temperature solution polymerization conditions in DMAc. The model diamide, 2,8-ditolylcarbamylthiaxanthone-5,5′-dioxide was synthesised and characterized by spectroscopic methods. The polyamides were prepared in 70–80% yield and had inherent viscosity in the 0.36–0.73 dL/g range. The poyamides have decomposition temperatures in the 425–510°C range in nitrogen. The effect of thiaxanthone rings on polymer backbone on solubility, crystallinity, and thermal stability is also discussed.     

羧基化含氟聚芳醚的合成及涂层性能

以四烯丙基联苯二酚(TABP)、 双酚A和十氟联苯为原料, 通过室温缩聚制得含氟聚芳醚(FPAEs), 再将其与3-巯基丙酸进行加成, 制得羧基化含氟聚芳醚(CFPAEs). 通过改变TABP的投料量来调节产物的羧基含量. 以N-甲基吡咯烷酮(NMP)为溶剂, 将CFPAE涂层喷涂在马口铁上. 研究发现, CFPAE涂层具有优异的热稳定性和机械强度, 羧基的引入可显著提高含氟聚芳醚涂层的附着力. 当羧基含量为0.265 mmol/g时, 涂层的黏附力等级为0级, 铅笔硬度为6H, 不引起涂层破坏的最小轴棒直径为0.5 mm, 水接触角为103.9°. 此外, CFPAE涂层还具有优异的耐酸、 耐盐、 抗紫外老化和防腐蚀等性能. 研究结果表明, 羧基化是拓展含氟聚芳醚在特种氟碳涂料上应用的一种有效途径.     

Synthesis of poly(benzylidene phthalide)s: A new class of polymers

Pyromellitic dianhydride (PMDA) was condensed with different aromatic diacetic acids via a Perkin reaction to produce new polymers containing the benzylidenephthalide group in the backbone. Yields ranged from 50 to 90% with inherent viscosities ranging from 0.07 to 0.37 dL/g. Polymerizations at 275°C for 4 h using p-phenylenediacetic acid and PMDA gave the polymer with highest inherent viscosity. However, polymerization under identical conditions of p,p′-diphenyl ether diacetic acid, each with PMDA, yielded poor results. For these two monomers the best polymerization conditions were 250°C for 8 h. In general, the most thermally stable polymer was derived from the diphenyl ether diacetic acid monomer (308°C). This polymer was obtained in highest yields and gave the greatest amount of pyrolytic residue in argon (67%).     

Synthesis and characterization of new poly(arylene ether)s containing heterocyclic units. II.

A series of new poly(arylene ether)s, containing naphthalene, pyridine, and quinoline units have been prepared by solution condensation polymerization. The synthesis involves nucleophilic displacement of aromatic dihalides with aromatic potassium bisphenates in an anhydrous dipolar aprotic solvent at elevated temperatures. The polymers, having inherent viscosity from 0.24 to 1.32 dL/g, were obtained in quantitative yield, have excellent thermal stability as shown by 10% weight loss temperatures in nitrogen and air (above 450 and 430°C, respectively) and high glass transition temperatures (in the range of 150–220°C). The introduction of quinoline moieties in the polymer backbone positively influences the thermal properties, such as high T_g/T_m ratios. © 1995 John Wiley & Sons, Inc.     

Allyl-containing polyaryl ethers with perfluorinated mono- and biphenylene fragments

A method for the synthesis of fluorinated allyl-containing bisphenol based on 4,4′-[(2,3,5,6-tetrafluoro-1,4-phenylene)bis(oxy)]diphenol has been elaborated. Curable aromatic polyethers have been prepared via polycondensation of the synthesized bisphenol with decafluorobiphenyl. The influence of bases, namely K₂CO₃ and NaH, on the molecular weights of polymers has been studied, and the conditions of their curing at allyl moieties have been found. Mechanical, physicochemical, and dielectric properties of allylcontaining polymers are dependent on the method of their preparation and curing.     

Bulk polymerization of p‐dioxanone using a cyclic tin alkoxide as initiator

Poly(p‐dioxanone) with an inherent viscosity of over 1 dL/g has been synthesized using the cyclic tin alkoxide 1‐di‐n‐butyl‐1‐stanna‐2,5‐dioxacyclopentane as initiator. Poly(p‐dioxanone) was synthesized in bulk and the results have been compared with polymerizations using tin (II) 2‐ethylhexanoate (Sn(Oct)₂) as catalyst. Sn(Oct)₂ has often been reported to be an effective catalyst for the synthesis of poly(p‐dioxanone), but here it is compared with an initiator which is less prone to catalyze transesterification reactions. The results demonstrate that the cyclic tin initiator is a promising alternative for the synthesis of poly(p‐dioxanone) with a high inherent viscosity. Poly(p‐dioxanone) is a polymer with mechanical properties and a degradation rate suitable for tissue engineering applications. Both the cyclic tin initiator and Sn(Oct)₂ gave, under some reaction conditions, inherent viscosities around 1 dL/g. The best polymer synthesized using the cyclic tin initiator had a strain‐at‐break of 515% and a stress‐at‐break of 43 MPa. The inherent viscosity of this polymer was 1.16 dL/g, while Sn(Oct)₂ resulted in a polymer with an inherent viscosity less than 0.4 dL/g under the same reaction conditions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5552–5558, 2007     

Novel photocurable multifunctional acrylate monomers containing perfluorinated aromatic units and their copolymers for photonic applications

We designed and synthesized novel UV‐curable multifunctional acrylate monomers with perfluorinated aromatic units and their copolymers. The UV‐curable multifunctional acrylate monomers with perfluorinated aromatic units were synthesized as follows. Perfluorinated aromatic methylmethane derivatives were prepared through the reaction of pentaerythritol with hexafluorobenzene and decafluorobiphenyl in the presence of sodium hydride. They were sequentially substituted with 2,2,3,3,4,4,5,5‐octafluoro‐6‐(tetrahydropyran‐2‐yloxy)‐hexan‐1‐ol, and this yielded hydroxy‐functional compounds after tetrahydropyran deprotection. Finally, the reaction of the resultant hydroxy compounds with acryloyl chloride generated the perfluorinated multifunctional acrylate monomers in high yields of greater than 85%. The novel photocrosslinked and perfluorinated copolyacrylates, obtained after the UV and thermal curing of these monomers, satisfied the material requirements for photonic devices. Most of these copolymers were thermally stable over 370 °C, and their glass‐transition temperatures were not detected because of their highly crosslinked nature. The refractive indices of the copolymers ranged from 1.410 to 1.441. The refractive indices of the photocrosslinked and perfluorinated copolyacrylates were easily tuned by the variation of the copolymer composition. Some of these copolymers exhibited a birefringence of less than 0.0003. This was much lower than the birefringence of fluorinated polyacrylate‐based materials. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6375–6383, 2004     

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.     

Low molecular weight aromatic compounds possessing a nonflammable characteristic in fluoroalkyl end‐capped acrylic acid oligomer/silica nanocomposite matrices after calcination at 800 °C under atmospheric conditions

Fluoroalkyl end‐capped acrylic acid oligomer [R_F‐(ACA)_n‐R_F] reacted with tetraethoxysilane and silica nanoparticles in the presence of low molecular weight aromatic compounds [ Ar‐H ] such as cetylpyridinium chloride (CPC) and bisphenol AF under alkaline conditions to afford R_F‐(ACA)_n‐R_F/SiO₂ nanocomposites‐encapsulated Ar‐H in 47–94% isolated yields. These fluorinated silica nanocomposites‐encapsulated Ar‐H can exhibit no weight loss behavior corresponding to the contents of Ar‐H after calcination at 800 °C under atmospheric conditions, although fluoroalkyl end‐capped acrylic acid oligomer in the nanocomposites decomposed completely under similar conditions. UV‐vis spectra of well‐dispersed methanol solutions of R_F‐(ACA)_n‐R_F/SiO₂/CPC nanocomposites before calcination show that CPC can be encapsulated into fluorinated silica nanocomposites with encapsulated ratios: 23–43%. The fluorinated nanocomposites after calcination was found to exhibit a higher antibacterial activity related to the presence of CPC in the composites. Encapsulated bisphenol AF into R_F‐(ACA)_n‐R_F/SiO₂ nanocomposites before and after calcination at 800 °C can exhibit a good releasing ability toward methanol with released ratios: 48 and 26%, respectively. ¹H MAS NMR, HPLC analysis, and LC‐MS spectra of R_F‐(ACA)_n‐R_F/silica nanocomposites‐encapsulated bisphenol AF also showed the presence of bisphenol AF in the nanocomposites even after calcination at 800 °C under atmospheric conditions. These findings suggest that CPC and bisphenol AF can exhibit a nonflammable characteristic in the fluorinated silica nanocomposites. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Preparation of polyamide-imides via the phosphorylation reaction. II. Synthesis of wholly aromatic polyamide-imides from N-[p-(or m-) carboxyphenyl]trimellitimides and various aromatic diamines

Wholly aromatic polyamide-imides with high molecular weight (η_inh up to 1.7 dL/g in DMAc–5% LiCl) were obtained by the direct polycondensation reaction of N-[p-( or m-) carboxyphenyl]trimellitimide [p-(or m-)CPTMI] and aromatic diamines by means of di- or triphenyl phosphite in N-methyl-2-pyrrolidone (NMP)-pyridine solution in the presence of lithium or calcium chloride. The factors affecting the phosphorylation reaction were investigated, in particular for the reaction of p-CPTMI and 4,4'-oxydianiline (ODA). Molecular weight of polymers varied with the amount of metal salts and showed maximum values at the concentration of 10-15 wt % in the reaction mixture. Monomer concentration of 0.2 mol/L produced polymer of the highest viscosity. Higher concentrations produced gelation and yielded polymers of low molecular weight. A reaction temperature of about 120°C gave the best results. Among the solvents tested, NMP was significantly the most effective for the reaction. The highest inherent viscosity values, η_inh = 1.35 and 1.58 dL/g, were obtained with triphenyl phosphite (TPP)/monomer and diphenyl phosphite (DPP)/monomer molar ratios of 2.0. Excessive addition of phosphites did not cause a serious deleterious effect on the molecular weight of polymer. Polycondensations of several combinations of p-or m-CPTMI and aromatic diamines were carried out with satisfactory results.     

Preparation and characterization of fluorine‐containing aromatic condensation polymers. VII. Aromatic polyacetals and copolyacetals from 2,2‐bis(4‐hydroxyphenyl)‐1,1,1,3,3,3‐hexafluoropropane and/or 2,2‐bis(4‐hydroxyphenyl)propane and 2‐(trifluoromethyl)benzal chloride

A series of fluorine‐containing aromatic homopolyacetals and copolyacetals with a wide range of unit ratios were synthesized by the solution polycondensation of 2,2‐bis(4‐hydroxyphenyl)‐1,1,1,3,3,3‐hexafluoropropane (bisphenol AF), 2,2‐bis(4‐hydroxyphenyl)propane (bisphenol A), or both with 2‐(trifluoromethyl)benzal chloride, and the effect of fluorine substitution on the properties of these polymers is discussed in relation to the fluorine contents. High molecular weight polyacetals with reduced viscosities of 0.43–0.97 dL/g were obtained in high yields with potassium hydroxide as a base, 18‐crown 6‐ether as a catalyst, and N‐methyl‐2‐pyrrolidinone as a medium at 100 °C for 3 h. Regardless of the fluorine contents, these polymers all were highly soluble in various solvents, including benzene, chloroform, ethyl acetate, and tetrahydrofuran, and afforded colorless, transparent, and tough films by solution casting. The temperatures of 5% weight loss and 10% weight loss under nitrogen both increased significantly and monotonously with increasing fluorine content, whereas the glass‐transition temperatures were scarcely affected by fluorine substitution. The dielectric constant at 1 MHz of the bisphenol AF‐based homopolyacetal was 2.43, which was remarkably lower than the value of the bisphenol A‐based homopolyacetal, 2.68. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1873–1879, 2000     

Synthesis and characterization of new aromatic polyesters and a polyether derived from 2,2-bis(4-hydroxyphenyl)-1,2-diphenylethanone

New polyarylates having benzopinacolone units were synthesized from 2,2-bis(4-hydroxyphenyl)-1,2-diphenylethanone and aromatic dicarboxylic acid chlorides. The polymers having an inherent viscosity of 0.71–0.94 dL/g were obtained by the two-phase method using toluene as an organic solvent. The polymers were easily soluble in various organic solvents and had high glass transition temperatures in the range of 200–240°C. An aromatic polyether having benzopinacolone unit was also prepared. However, its inherent viscosity was low because of the occurrence of a side reaction. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2229–2235, 1998     

Behavior of 3,6-Bis(vinylsulfonyl)-1,2,4,5-tetrafluorobenzene in Homolytic Addition of Dialkyl Phosphites

Reaction of 3,6-bis(vinylsulfonyl)-1,2,4,5-tetrafluorobenzene with dialkyl phosphites at thermal initiation (70°C) gives rise to 3,6-bis(dialkoxyphosphonoethylsulfonyl)-1,2,4,5-tetrafluorobenzenes in up to 45% yield. The formation of diethoxyphosphonyl radicals in the course of the reaction was observed with the use of ESR method applying spin trapping by 2-methyl-2-nitrosopropane. The use as initiator of the azo-bis-isobutyronitrile increased the yield of diadducts to 60%.     

Polyamides with pendant 1,3,4-oxadiazole and pyridine moieties

A novel aromatic diamine,2-（5-（3,5-diaminophenyl）-l,3,4-oxadiazole-2-yl）pyridine（POBD）,containing a pyridine ring and a 1,3,4-oxadiazole moiety,was synthesized.It was used in a polycondensation with various aromatic and aliphatic diacid chlorides to generate a series of new aromatic polyamides with pendant 1,3,4-oxadiazole groups.The prepared polyamides were characterized by IR,elemental analysis and through the synthesis of model compounds.Thermophysical properties of the synthesized polyamides have been studied by DSC,TGA and inherent viscosity measurements. Relatively high inherent viscosity values（0.76-1.62 dL/g,in 0.125%H₂SO₄ at 25℃） were observed for these compounds. Number average molecular weight（M_n） of the polymers was measured by vapor phase osmometry（VPO）.The introduction of bulky side chains in the structure of aromatic polyamides led to increased solubility of these polymers in common polar and aprotic solvents,such as DMF,DMSO,NMP and DMAc,which allowed thin films to be cast from polymer solutions. The highest molecular weight（M_n = 51190） was observed for polymer（DC）,which was prepared from pyridine-2,6-dichlorocarbonyl.     

Poly(aryl ether ketone)s with (3‐methyl)phenyl and (3‐trifluoromethyl)phenyl side groups

New bisphenol monomers, (3‐methyl)phenylhydroquinone and (3‐trifluoromethyl)phenylhydroquinone, were prepared in a two‐step synthesis. A series of poly(aryl ether ketone)s were derived from these bisphenols via a nucleophilic aromatic substitution polycondensation with various bisfluoro compounds. The polycondensation proceeded quantitatively in tetramethylene sulfone in the presence of anhydrous potassium carbonate and afforded the polymers with inherent viscosities of 0.63–0.91 dL/g. The fluorinated polymers showed lower glass‐transition temperatures and higher thermal‐decomposition temperatures than the corresponding nonfluorinated polymers. The solubility of the polymers was improved by the introduction of bulky pendant groups. All the polymers formed transparent, strong, and flexible films, with tensile strengths of 86.4–102.0 MPa, Young's moduli of 2.28–3.03 GPa, and elongations at break of 14–42%. All the polymers had low dielectric constants of 2.70–2.83 at 1 MHz. Compared with the methylated polymers, the trifluoromethylated polymers exhibited lower water sorption, which was attributed to the stronger hydrophobicity of the fluorine‐containing groups. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3392–3398, 2002     

Synthesis and properties of fluorinated polyimides from a new unsymmetrical diamine: 1,4‐(2′‐Trifluoromethyl‐4′,4′‐diaminodiphenoxy)benzene

A new aromatic, unsymmetrical ether diamine with a trifluoromethyl pendent group, 1,4‐(2′‐trifluoromethyl‐4′,4″‐diaminodiphenoxy)benzene, was successfully synthesized in three steps with hydroquinone as a starting material and polymerized with various aromatic tetracarboxylic acid dianhydrides, including 4,4′‐oxydiphthalic anhydride, 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride, 2,2′‐bis(3,4‐dicarboxyphenyl)‐hexafluoropropane dianhydride, and pyromellitic dianhydride, via a conventional two‐step thermal or chemical imidization method to produce a series of fluorinated polyimides. The polyimides were characterized with solubility tests, viscosity measurements, IR, ¹H NMR, and ¹³C NMR spectroscopy, X‐ray diffraction studies, and thermogravimetric analysis. The polyimides had inherent viscosities of 0.56–0.77 dL/g and were easily dissolved in both polar, aprotic solvents and common, low‐boiling‐point solvents. The resulting strong and flexible polyimide films exhibited excellent thermal stability, with decomposition temperatures (at 5% weight loss) above 522 °C and glass‐transition temperatures in the range of 232–272 °C. Moreover, the polymer films showed outstanding mechanical properties, with tensile strengths of 74.5–121.7 MPa, elongations at break of 6–13%, and initial moduli of 1.46–1.95 GPa, and good dielectric properties, with low dielectric constants of 1.82–2.53 at 10 MHz. Wide‐angle X‐ray diffraction measurements revealed that these polyimides were predominantly amorphous. These outstanding combined features ensure that the polymers are desirable candidate materials for advanced microelectronic applications. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6836–6846, 2006