Synthesis and properties of aromatic polyamides based on 4,4′-(1,5-naphthalenedioxy)dibenzoic acid

4,4′-(1,5-Naphthalenedioxy)dibenzoic acid ( 3 ), a novel aromatic dicarboxylic acid monomer, was prepared by nucleophilic substitution reaction of 1,5-dihydroxynaphthalene and p-fluorobenzonitrile in N,N-dimethylformamide (DMF) in the presence of potassium carbonate and subsequent alkaline hydrolysis of the intermediate dinitrile, 4,4′-(1,5-naphthalenendioxy)dibenzonitrile. Using triphenyl phosphite (TPP) and pyridine as condensing agents, a series of novel aromatic polyamides were synthesized by direct poly-condensation of diacid 3 and twelve aromatic diamines in N-methyl-2-pyrrolidone (NMP) solution containing dissolved calcium chloride. The resulting polyamides had inherent viscosities above 1,14 and up to 4,45 dL/g. Most of these polyamides are readily soluble in polar solvents, such as NMP, DMF, and N,N-dimethylacetamide (DMAc). Transparent, flexible, and tough films could be cast from their DMAc or NMP solutions. Most of these polymers were amorphous in nature, as indicated by their wide-angle X-ray diffractograms. Thermogravimetric analysis (TG) showed that all the polyamides were stable up to 450°C in both air and nitrogen atmosphere. Most of them revealed a distinct glass transition on the differential scanning calorimetry (DSC) traces in the range of 183–259°C.     

Preparation and characterization of fluorine-containing aromatic condensation polymers, 5. Aromatic polybenzimidazoles from 4,4′-(hexafluoroisopropylidene)dibenzoic acid and aromatic tetramine tetrahydrochlorides

Two novel fluorine-containing aromatic polybenzimidazoles were synthesized by direct polycondensation of 4,4′-(hexafluoroisopropylidene)dibenzoic acid with 3,3′-diaminobenzidine tetrahydrochloride and 1,2,4,5-benzenetetramine tetrahydrochloride. The effect of introduction of fluorine on the synthesis and properties of these polymers is discussed. The new polybenzimidazoles show good solubility in organic solvents, excellent mechanical properties and high thermal stability.     

Synthesis and properties of poly(ether imide)s derived from 4,4′-(1,5-naphthylenedioxy)diphthalic anhydride and various aromatic diamines

A naphthalene unit-containing bis(ether anhydride), 4,4′-(1,5-naphthylenedioxy)-diphthalic anhydride, was prepared in three steps starting from the nucleophilic nitro-displacement reaction of 1,5-dihydroxynaphthalene and 4-nitrophthalonitrile in N,N-dimethylformamide (DMF) solution in the presence of potassium carbonate. High-molarmass aromatic poly(ether imide)s were synthesized using a two-stage polymerization process from the bis(ether anhydride) and ten aromatic diamines. The intermediate poly(ether amic acid)s had inherent viscosities of 0,66–1,27 dL/g. The films of poly(ether imide)s derived from some diamines, such as p-phenylenediamine, benzidine, and bis[4-(4-aminophenoxy)phenyl] ether, crystallized and embrittled during the thermal imidization process. The other poly(ether imide)s were amorphous materials and could be fabricated into transparent, flexible, and tough films. These poly(ether imide) films had yield strengths of 111–125 MPa, tensile strengths of 96–150 MPa, elongations to break of 10–38%, and initial moduli of 1,6–2,4 GPa. All of these polymers were insoluble in organic solvents, except for that derived from 2,2-bis[(4-aminophenoxy)phenyl]propane. Their T_g's were recorded in the range of 226–265°C by DSC. Thermogravimetric analysis (TG) showed that all the polymers were stable up to 535°C in both air and nitrogen atmosphere.     

Synthesis and properties of polyimides derived from 4,4′-(2,7-naphthylenedioxy)dianiline and aromatic tetracarboxylic dianhydrides

Novel polyimides containing 2,7-diphenoxynaphthalene moieties were prepared from 4,4′-(2,7-naphthylenedioxy)dianiline (DAPON) and various aromatic tetracarboxylic dianhydrides via a two-stage procedure that includes ring-opening polyaddition in a polar solvent such as N,N-dimethylacetamide to give poly(amic acid)s, followed by cyclodehydration to polyimides. The poly(amic acid)s exhibit inherent viscosities between 0,63 and 1,94 dL/g depending on the tetracarboxylic dianhydrides used. Except for the polyimide 4d , obtained from 3,4 : 3′,4′-benzophenonetetracarboxylic dianhydride ( 2d ), all polymides from yellow, flexible, and tough films upon casting from the poly(amic acid) solutions. Polyimide 4e derived from 4,4′-sulfonyldiphthalic anhydride ( 2e ) exhibits better solubility than the other polymides. The polyimides synthesized from and 2d are semicrystalline polymers, whereas the other polyimides are amorphous due to their X-ray diffractograms. Tensile strength and elongation of the DAPON-based polyimide films from 86–107 MPa and 6–25% respectively. These polyimides have glass transition temperature 223 and 285°C . Thermal analyses indicated that these polymers are fairly stable, and the 10% weight loss temperatures were recorded in the ranges 568–581 °C in nitrogen and 557–570°C in air.     

Synthesis and properties of aromatic polyamides based on 4,4′-[1,4(1,3 or 1,2)-phenylenedioxy]dibenzoic acid

Three isomeric bis(ether carboxylic acid)s, 4,4′-[1,2(1,3 or 1,4)-phenylenedioxy]dibenzoic acid (o-, m-, or p- 3 ) were prepared by nucleophilic substitution reaction of the potassium phenolate of catechol, resorcinol, and hydroquinone, respectively, with p-fluorobenzonitrile, giving the corresponding bis(ether nitrile)s, followed by alkaline hydrolysis. There series of isomeric polyamides were synthesized by direct polycondensation of the bis(ether carboxylic acid)s with various aromatic diamines in N-methyl-2-pyrrolidone (NMP) solution containing dissolved metal salts such as CaCl₂ or LiCl using triphenyl phosphite and pyridine as condensing agents. The resultant polyamides had inherent viscosities of 0,52–1,63 dL/g. Most of the polymers were soluble in polar aprotic solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), NMP, and dimethyl sulfoxide. The catechol-based polyamides revealed markedly higher solubility than those based on hydroquinone or resorcinol. Transparent, flexible and tough films could be cast from the DMAc or NMP solutions of most of the polyamides. All the casting films were characterized by tensile tests. The glass transition temperatures (T_g's) of most polyamides could be determined with the help of differential scanning calorimetry (DSC) traces, which were recorded in the range of 183–232°C. In general, the polyamides based on catechol had T_g's comparable with the ones of the hydroquinone-based polyamides and higher T_g's than the corresponding resorcinol-based ones. Thermogravimetric analysis data of these polymers indicated that all the polyamides were stable up to 400°C in both air and nitrogen atmospheres.     

Polychelates derived from 4,4′-(4,4′-biphenylylenebisazo)di(salicylaldehyde oxime)

Polychelates of Ni(II), Co(II), Cu(II), Zn(II), and Mn(II) were synthesized from bis 4,4′-(4,4′-biphenylenebisazo)di(salicylaldehyde oxime) and metal chlorides. All the chelates are dark in colour and insoluble in common organic solvents. Their most probable structures were determined by visible reflectance spectroscopy and magnetic measurements in conjunction with thermogravimetric and IR measurements. Elemental analyses indicate a ligand: metal ratio of 1:1 and the association of water molecules with the central metal. The decomposition temperatures of the polychelates decrease in the following order: Zn(II) > Co(II) > Ni(II) > Mn(II) > Cu(II).     

“Liquid crystalline” thermosets from 4,4′-bis(2,3-epoxypropoxy)biphenyl and aromatic diamines

Pure 4,4′-bis(2,3-epoxypropoxy)biphenyl ( 1 ) has been synthesized and its mesophase behaviour has been investigated. 1 forms a monotropic nematic mesophase with a virtual clearing temperature of 109°C. 1 has been cured with 2,4-diaminotoluene ( 3 ), 4,4′-diaminobiphenyl ( 4 ), and 4-aminophenyl 4-aminobenzoate ( 5 ) to investigate the possibility of formation of anisotropic networks. Virtual clearing temperatures of the diamines indicate that liquid crystalline thermosets (LCT's) might be obtained with 4 and 5 . Crystallization of oligomeric products from the isotropic melt of 1 with 3 or 4 , respectively, occurred on isothermal curing without formation of a mesophase, while a nematic LCT was obtained with 5 .     

Preparation and properties of novel aromatic poly(thioethers) derived from 4,4′-thiobisbenzenethiol

A series of amorphous and semicrystalline aromatic poly(thioethers) have been prepared by the reactions of 4,4′-thiobisbenzenethiol and activated dihalides. Azo group activated dihalide monomer was prepared by the reactions of 4-fluoronitrosobenzene with a suitable diamine. The keto and phosphine sulfide containing monomers were synthesized by Friedel-Crafts acylation reactions of suitable halobenzenes with appropriate acid chlorides. Potassium carbonate mediated reactions in dimethylacetamide afforded moderate to high molecular weight polymers. Polymers with high melting points were prepared by using diphenyl sulfone as a co-solvent. The poly(thioethers) exhibit high glass transition temperatures and/or high melting points. In addition, the polymers exhibit excellent thermal stability.     

Synthesis of aromatic polyamides from reactive N,N′-isophthaloyldi(thiolactam)s and aromatic diamines under mild conditions

Solution condensation polymerization of new reactive diamides, N, N′-isophthaloyldipyrrolidine-2-thione ( 1a ) and N, N′-isophthaloyldiperhydroazepine-2-thione ( 1b ), with aromatic diamines 2 in 1-methyl-2-pyrrolidone at room temperature or above leads to polyamides 3 with moderate molecular weights. The ease of aminolysis of these diamides is discussed in relation to the good leaving nature of the thiolactam moieties and an intramolecular general base catalysis. The condensation polymerization is strongly catalyzed by 1-hydroxybenzotriazole giving aromatic polyamides with higher inherent viscosities up to 0,9 dl.g^?1.     

Synthesis and characterization of some aliphatic polyamides containing 4,4′-azodiphenylene units

Polyamides containing azo groups were prepared by the phosphorylation method from 4,4′-diaminoazobenzene and malonic, succinic, glutaric, adipic, azelaic, sebacic, or chlorosuccinic acid. The polymers were characterized by their viscosity and solubility, and by UV-visible and IR spectroscopy, TG, and DTA.     

Synthesis of polyamides containing 4,4′-azodibenzamido units

Four coloured polyamides containing azo-p-phenylene units were synthesised from 4,4′-azodibenzoic acid and four aromatic diamines employing both interfacial and solution polymerization procedures. The polymers were characterized by their UV and IR spectra, by inherent viscosity measurements and by solubility data. The stability in conc. sulfuric acid and the thermal behaviour are discussed.     

Synthesis and characterization of polyamides deriving from 2,2′-[sulfonylbis(1,4-phenyleneoxy)]diacetic acid

Six semi-aromatic polyamides ( 3a–f ) were synthesized by low temperature solution polycondensation of aromatic diamines ( 1a–;f ), containing flexible groups such as ? CH₂? , ? CH₂? CH₂? , ? O? , ? S? , and ? SO₂? , with 2,′2-[sulfonylbis(1,4-phenyleneoxy)]-diacetyl chloride ( 2 ) in a solvent mixture of NMP and HMPT (vol. ratio 2 : 1). All the polyamides posses inherent viscosities in the range of 0,31 to 0,73 dl/g. They are soluble in polar amides and DMSO. The molecular weights, molecular weight distributions, thermal stabilities, thermal degradation kinetics and percentages of crystallinity were determined.     

Poly(amide-imide)s prepared from 4,4′-[1,4(or 1,3)- phenylenebis(isopropylidene-1,4-phenyleneoxy)]dianiline,trimellitic anhydride,and various aromatic diamines

Two imide ring-bearing dicarboxylic acids, N,N′-[1,4(or 1,3)-phenylenebis(isopropylidene-1,4-phenyleneoxy-1,4-phenylene)]diphthalimide-4-carboxylic acid (p-4 and m-4), were prepared via condensation of 4,4′-[1,4(or 1,3)-phenylenebis(isopropylidene-1,4-phenyleneoxy)]dianiline (p-3 and m-3) with trimellitic anhydride. Two series of novel poly(amideimide)s were synthesized by the direct polycondensation of the diimide-diacids p-4 and m-4, respectively, with various aromatic diamines using triphenyl phosphite and pyridine as condensing agents. The inherent viscosities of the resultant poly(amide-imide)s were in the range of 0,43–1,68 dL/g, and most of these polymers were amorphous, as revealed by wideangle X-ray diffractograms. Almost all the poly(amide-imide)s were readily soluble in polar aprotic solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), and N,N-dimethylformamide (DMF), and could be solution-cast into transparent, flexible, and tough films. These polymers had glass transition temperatures in the range of 200-267°C and showed no significant decomposition below 450°C, with 10% weight loss being recorded above 485°C in nitrogen or air.     

Polymers of carbonic acid, 5. Nematic polyurethanes derived from 4,4′-dihydroxybiphenyl and 4,4′-bipiperidine,ethylene-4,4′-bipiperidine or trimethylene-4,4′-bipiperidine

4,4′-Bipiperidine ( 3a ), 1,2-bis(4-piperidinyl)ethane ( 3b ) and 1,3-bis(4-piperidinyl)propane ( 3c ) were condensed with the dichloroformates of p-phenylene, 2-methyl-1,4-phenylene or 2,5-biphenylylene. Furthermore, two copolyurethanes were prepared either by mixing 3a and 3c or by mixing the dichloroformates for p-phenylene and 2,5-biphenylylene. Inherent viscosities between of 0,6 and 1,7 dl/g were found for the polyurethanes of 3c , but only values below 0,86 dl/g for those of 3a and 3b . The polyurethanes derived from hydroquinone or methylhydroquinone are semicrystalline polymers with a short-term thermostability up to 310°C. The polyurethanes deriving from phenylhydroquinone are amorphous with a thermostability up to 360°C. The homo-and copolyurethanes containing 4,4′-biphenylylene units form a smectic layer structure in the solid state and a nematic melt above the melting point.     

High performance aromatic polyimide fibers, 3. A polyimide synthesized from 3,3′,4,4′-biphenyltetracarboxylic dianhydride and 2,2′-dimethyl-4,4′-diaminobiphenyl

A new high molecular weight aromatic polyimide has been synthesized from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 2,2′-dimethyl-4,4′-diaminobiphenyl (DMB) in p-chlorophenol at elevated temperature. BPDA-DMB fibers have been spun by a dry-jet wet spinning method. The fibers were elongated and annealed at elevated temperatures above 400°C to achieve excellent mechanical properties. In seven times drawn fibers, the BPDA-DMB molecule packs into a triclinic unit cell with dimensions of a = 2,10(2) nm, b = 1,523(8) nm, c = 4,12(7) nm, α = 61,2(6)°, β = 50,7(7)°, and γ = 78,9(6)° with the number of chain repeating units per unit cell (Z) is sixteen. After annealing at elevated temperatures, the fibers produce a small modification of the unit cell [a = 2,048(6) nm, b = 1,529(5) nm, c = 4,00(2) nm, α = 62,1(3)°, β = 52,2(3)° and γ = 79,6(3)°]. By increasing the draw ratio, both the crystallinity and crystal orientation increase. The BPDA-DMB fibers possess a decomposition temperature of 530°C in nitrogen and 500°C in air at a 5% weight loss when the heating rate is 10°C/min. After extensive drawing, BPDA-DMB fibers exhibit a tensile strength of 3,3 GPa and a tensile modulus of over 130 GPa. Dynamic mechanical behavior of the fibers show both α (glass transition) and β (sub-glass transition) relaxations above room temperature. The nature of the sub-glass transition behavior is described as a noncooperative motion attributed to the diamine portion of the molecule. The activation energy for this relaxation in as-spun fibers is 109 kJ/mol and increases to 144 kJ/mol by increasing the draw ratio. This β relaxation is found to be crystallinity dependent. The α transition is also suppressed by crystallinity which increases with draw ratio.     

Polyamides from 2,2′-p-phenylenebis(Δ2-5-oxazolone)s and N,N′-bistrimethylsilylated diamines. Synthesis of polyamides containing dipeptide links in the main chains

A new polyamidation reaction between N,N′-bistrimethylsilylated diamines and 2,2′-p-phenylenebisazalactones in N,N-dimethylacetamide was investigated. By the interaction of bisazalactones with N^α, N^ε-bistrimethylsilylated L-lysin alkyl ester, polyamides were obtained containing dipeptide links in the main chain. It was shown that these can be transformed into water-soluble polyacids upon saponification of ester side groups.     

Thermotropic para-linked aromatic polyesters containing 1,1′-binaphthyl-4,4′-ylene units

Synthesis, thermal properties and solubility behaviour of para-linked aromatic homopolyesters containing non-coplanar 1,1′-binaphthyl-4,4′-ylene units are described. By combining such binaphthylylene units with monosubstituted phenylene units, crystallization can be suppressed and thermotropic liquid-crystalline polyesters with glass transition temperatures (T_g) up to 190°C are obtainable. The liquid-crystalline order is maintained below T_g in an anisotropic glass. The polyesters show good solubility in common organic solvents, such as chloroform or tetrahydrofuran.     

Photocrosslinkable polymers for membranes: polyamides from N-cinnamoyl-5-aminoisophthalic acid and aromatic diamines

N-Cinnamoyl-5-aminoisophthalic acid was synthesized by acylation of 5-aminoisophthalic acid with cinnamoyl chloride in N,N-dimethylacetamide (DMAc) solution. The direct polycondensation of the new diacid with various aromatic diamines results in a new type of photoreactive aromatic polyamides with inherent viscosities of 0,4–1,7 dL/g. The preparation of homogeneous and asymmetric photocrosslinkable membranes from N-methyl-2-pyrrolidone (NMP) solution was performed. The mechanical stability of a film was improved by UV irradiation while the permselectivities of ethanol/water and (tert-butyl methyl ether)/methanol mixtures were not influenced by the photochemical crosslinking.     

Electro- and photo-initiated polymerization of N,N′-(4,4′-sulfonyldiphenylene)dimaleimide

A study has been made of the electro- and photo-initiated polymerization of N,N′-(4,4′-sulfonyldiphenylene)dimaleimide ( 4 ) in the presence of zinc dibromide and toluene. Product yields were linearly dependent on the photo irradiation or current passage times. The reaction mechanism appears to be a 2π+2π cycloaddition resulting in the electro or photo condensation of 4 .