Studies on heat resistant poly(aryl pyromellitimide-ether)s

A new series of aromatic heterocyclic poly(aryl pyromellitimide-ether)s have been synthesized from various disodium metal bisphenolate salts with an N,N′-bis(p-nitrophenyl)pyromellitimide via aromatic nitro displacement solution polycondensation in dipolar aprotic solvent at elevated temperature. The reaction was rapid and free of side reactions, with good yield. The resultant polymers were characterized by intrinsic viscosity, infrared and ¹H-, ¹³C-NMR spectroscopy. Thermal behavior of the synthesized polymers was evaluated by thermogravimetric analysis and correlated with their structures. The poly(tetraphenyl methane pyromellitimide-ether) showed better thermal stability than the other polymers. © 1996 John Wiley & Sons, Inc.     

Synthesis of polymers in aqueous solutions: Polyaddition of bis(oxazolines) with dithiol in aqueous solutions

Polyaddition of bis(4-mercaptophenyl) sulfide ( BMPS ) with m-phenylenebis(2-oxazoline) ( MPBO ) proceeded very smoothly in the mixtures of aprotic ploar solvents such as N-methyl-2-pyrrolidone ( NMP ) with water to produce the corresponding poly(amide–sulfide) with high molecular weights at 90°C under nitrogen. The reaction of BMPS with MPBO , p-phenylenebis(2-oxazoline), and 1,4-butylenebis(2-oxazoline) was also examined in water under the same conditions, and it was found that the reaction proceeds successfully to give the corresponding poly(amide–sulfide)s with high molecular weights. These results mean that water along as well as the mixed solvents of aprotic polar solvents such as NMP with water can be uses as suitable reaction media for the polyaddition of bis(oxazolines) with dithiol to synthesize poly(amide—sulfide)s with high molecular weights. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2711–2717, 1997     

Synthesis and properties of novel aromatic polyamides derived from 1,5-bis(4-aminophenoxy)naphthalene and aromatic dicarboxylic acids

A new bis(phenoxy)naphthalene-containing diamine, 1,5-bis(4-aminophenoxy)naphthalene, was synthesized in two steps from the condensation of 1,5-dihydroxy-naphthalene with p-chloronitrobenzene in the presence of potassium carbonate, giving 1,5-bis(4-nitrophenoxy)naphthalene, followed by hydrazine hydrate/Pd? C reduction. A series of polyamides and copolyamides were synthesized by the direct polycondensation of the diamine with various aromatic dicarboxylic acids or with mixed dicarboxylic acids in N-methyl-2-pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. The polymers having inherent viscosity of 0.81–1.25 dL/g were obtained in quantitative yield. Most of the polymers were generally soluble in aprotic solvent such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, etc. The polymers derived from rigid dicarboxylic acids such as terephthalic acid, naphthalene dicarboxylic acid, and 4,4′-biphenyldicarboxylic acid exhibited crystalline patterns. Glass transition temperatures of polymers were in the range of 230–360°C, and 10% weight loss temperatures in nitrogen and air were above 492 and 470°C, respectively. © 1993 John Wiley & Sons, Inc.     

Polycondensation of bis(p-nitrophenyl) β-truxinate with diamine

Model reaction of bis(4-nitrophenyl) β-truxinate (BNPT) with aliphatic amines proceeded quantitatively at room temperature. Accordingly, polycondensation of BNPT with various diamines was carried out at room temperature or 80°C. During the polycondensation of BNPT with diamines, the precipitation of polymer or the observed gelation of polymerization solution occurred, which may limit the molecular weight of the polymer. On the other hand, the reaction of BNPT with 1,3-(4-piperidyl)propane (DPP) proceeded homogeneously to give the polymer with relatively high molecular weight, and the obtained polyamide (P-1e) showed excellent solubility in many solvents. The study of TG and DTA indicated that the obtained polymers were stable at lower temperature than around 270°C. The polymer prepared from the polycondensation of BNPT with hexamethylenediamine showed melting point and decomposition due to the imidation at 282°C. The photochemical reaction of these polymers was carried out in the film state. The irradiation of 254 nm light caused an absorption at 272 nm to appear and the molecular weight to decrease. This meant that the scission of cyclobutane ring in the main chain occurred to give cinnamamide structures. Also, the absorption at 272 nm decreased by the irradiation of 302.5 nm light. However, the UV spectrum of irradiated polymer did not agree with that of the original polymer. These results suggested that the dimerization of the resulting cinnamamide moieties occurred in the competition of their trans–cis-isomerization. On the other hand, the rate of scission of cyclobutane ring of P-1e was faster than that of the corresponding polyamide containing α-truxillamide structure.     

Modification of PP fibres with alkaline copolyamides

Copolyamides with 5.9‐19.7 wt.% of nylon salt ADETA (adipic acid + diethylenetriamine) and 94.1‐80.3 wt.% of ϵ‐caprolactam were synthesized and their properties were estimated. Blended polypropylene/copolyamides fibres containing 5‐15 wt.% of copolyamides were prepared and their properties were evaluated. The electrical properties, hydrophilicity and especially dyeability of modified PP fibres are positively influenced by a higher amount of the copolyamide in the PP and also by a higher amount of the nylon salt ADETA in the copolyamide.     

Novel synthesis of aromatic polysulfides from S,S′-bis(trimethylsilyl)-substituted aromatic dithiols and activated aromatic dihalides

A new method for the synthesis of aromatic polysulfides has been developed by the polycondensation of S,S′-bis(trimethylsilyl)-substituted aromatic dithiols with activated aromatic dihalides. The solution polycondensation of three S-silylated aromatic dithiols with bis(4-chloro-3-nitrophenyl) sulfone afforded readily aromatic polysulfides having inherent viscosities of 0.7 dL/g, and the polymerization with bis(4-fluorophenyl) sulfone gave the polymers with viscosity values of 0.3 dL/g. The silylation method was compared advantageously with a conventional route using parent dithiols and activated aromatic dihalides.     

On the Effect of the Aglycon Structure of Three Aryl β-D-Galactosides on the Yield and the Regioselectivity of the Transglycolytic Synthesis of N-Acetyllactosamine

ABSTRACT

We examined the effect as donors of three aryl β-D-galactosides (i.e. p-nitrophenyl β-D-galactopyranoside, o-nitrophenyl β-D-galactopyranoside and phenyl β-D-galacto-pyranoside) on the regioselectivity and the yield of the synthesis of N-acetyllactosamine obtained from the transglycosylation reaction catalyzed by a crude preparation of β-D-galactosidase from Bacillus circulans at 25 °C, 37 °C and 55 °C, respectively. Using p-nitrophenyl β-D-galactopyranoside the reaction results were fully regiospecific at all the temperatures considered: the maximum molar yield (74%) was obtained at an incubation temperature of 55 °C. Using o-nitrophenyl β-D-galactopyranoside as the donor the reaction was still highly regioselective and the maximum molar yield (50%) was achieved at an incubation temperature also of 55 °C. Using phenyl β-D-galactopyranoside transglycolytic products appear only at an incubation temperature of 55 °C but at very low molar yield (about 14%) and lower regioselectivity.     

Synthesis of aromatic polyamides by 1-hydroxybenzotriazole-catalyzed polycondensation of active aromatic diesters with aromatic diamines

Catalytic actions of various additives were studied in the polycondensation of di(4-nitrophenyl) isophthalate with bis(4-aminophenyl) ether in N-methyl-2-pyrrolidone, and 1-hydroxybenzotriazole (HOBt) was found to be a highly effective catalyst that yielded high-molecular-weight polyamide. In addition to the polycondensation of the 4-nitrophenyl ester, the polymerization of negatively substituted phenyl esters like di(2,4,5-trichlorophenyl) isophthalate was also accelerated by HOBt. For the HOBt-catalyzed aminolysis of esters a bifunctional concerted mechanism that involves an eight-membered transition state was proposed.     

Thermal properties of PA 6 and PA 6 modified with copolyamides and layered silicates

This article focuses on the thermal properties of PA 6 and additives, i.e. ternary copolyamides, concentrates consisting of binary or ternary copolyamides + nanoadditive montmorillonite Bentonite 11958 or Cloisite 15A and PA 6 fibres modified with Bentonite, copolyamide and concentrate. The copolyamides are prepared from ε-caprolactam as a major comonomer and nylon salts AN2 from adipic acid + 1-(2-aminoethyl)piperazine and ADETA from adipic acid + diethylenetriamine. All copolyamides and concentrates exhibit lower melting temperatures T _m and lower melting enthalpies ΔH _m compared to neat PA 6. PA 6 fibres modified with 0.25–2.5 wt% MMT exhibit higher melting enthalpies in comparison with unmodified PA 6 fibres. PA 6 fibres modified with 10 wt% of ternary copolyamide containing 21.4 wt% of comonomers AN2 and ADETA have higher melting enthalpy as well. PA 6 fibres modified with 10 and 20 wt% of concentrate containing the same ternary copolyamide + 5 wt% of MMT have higher melting enthalpies and higher tensile strength in comparison with these characteristics of unmodified PA 6 fibres.     

13C-NMR sequence analysis. 11. Anionic copolymerization of lactams

Using sodium as the catalyst and benzoylchloride as cocatalyst, copolymerizations of γ-butyrolactam with ε-caprolactam and ω-capryllactam were carried out at 100°C. In a similar manner copolymerizations of ε-cparolactam, ω-capryllactam, and ε-laurinlactam were achieved at 150 and 250°C without a cocatalyst. The 90.5-MHz ¹³C-NMR spectra of all random copolyamides in fluorosulfonic acid show three or more CO signals that allow the ratio of homogeneous (A? A and B? B) to heterogeneous (A? B and B? A) amide groups to be determined. These results cleárly demonstrate that despite the reaction temperature or reactivity of the lactams the copolyamides do not contain long homogeneous blocks (A_n and B_n). The CO signals of the random copolyamides were assigned by comparison with the corresponding homopolyamides and alternating copolyamides. Solutions of the alternating copolyamide (-β-Ala-ε-Aca-)_n, in fluorosulfonic acid were measured to determine whether the ¹³C chemical shifts and line widths are dependent on concentration.     

Isomorphism in copolyamides of long repeating chain units containing oxa- and thia-alkylene linkages

Various copolyamides of long repeating chain units were prepared from hexamethylenediamine (HMDA) and p-xylylenediamine (PXDA) with aliphatic dicarboxylic acids of three structural types: α,ω-alkanedioic, α,ω-oxaalkanedioic, and α,ω-thiaalkanedioic acids. Both binary and ternary combinations of these dicarboxylic acids having the same number of chain atoms with the diamine afforded highly crystalline copolyamides. In all cases of these copolymers, the plots of the melting points versus the compositions are expressed by linear relations, even in the ternary systems. For example, the melting points of the copolyamides of HMDA with 6-oxaundecanedioic and 6-thiaundecanedioic acids are practically unchanged in all ranges of composition. The same relation is also observed in the corresponding copolyamides of PXDA. The relation between the densities and the composition is plotted with good linearity in every case. From x-ray examination, the lattice spacings of each copolyamide are ascertained to be unchanged by the composition. These results reveal that methylene, ether, and thioether linkages are in the relation of isomorphous replacements for each other in these copolyamide systems. Moreover, the linear relationship between the melting point and the composition is explained by assuming that the entropy of fusion in these copolyamides changes linearly according to the change of the composition.     

Random copolyamides of terephthalic acid,p‐phenylenediamine and p‐aminobenzoic acid soluble in N‐methylpyrrolidone/CaCl2

Moderate‐molecular‐weight copolyamides soluble in N‐methylpyrrolidone (NMP) containing dissolved CaCl₂ can be obtained by polycondensation of terephthalic acid (TPA), p‐phenylenediamine (PPD), and p‐aminobenzoic acid (PABA) with triphenyl phosphite/pyridine in NMP. The randomly copolymerized polymers contain more than 40 mol‐% of PABA and are easily soluble in NMP.     

Poly(β-amino acid)s. IV. Synthesis and conformational properties of poly(α-isobutyl-L-aspartate)

Poly(α-isobutyl-L -aspartate) was prepared by the polycondensation reaction of p-nitrophenyl ester of α-isobutyl-L -aspartate and the conformation of the poly(β-amino acid) was investigated by X-ray diffraction, polarized infrared, circular dichroism (CD), optical rotatory dispersion (ORD), and NMR spectroscopy. α-Isobutyl β-p-nitrophenyl-L -aspartate hydrochloride and hydrobromide were used as monomers and dimethylformamide, chloroform, and chlorobenzene, as solvents. A high-molecular-weight polymer with [η] 1.0 dl/g (dichloroacetic acid, 25°C) was formed in the polymerization of the hydrochloride in chloroform at 25°C. The X-ray diagram and polarized infrared spectrum of the stretched polymer film obtained from a chloroform solution suggested a cross-β-form as the most probable structure in the solid state. The CD spectra of the polymer in a 2,2,2-trifluoroethanol (TFE) solution and its film cast from the solution showed a peak at 205 nm and a trough at 190 nm which were assigned to a β-structure. The polymer was associated in chloroform. The NMR and ORD spectra in chloroform were similar to those in TFE, which suggests that the polymer also exists in the β-structure in chloroform. The addition of small amounts of dichloroacetic acid and sulfuric acid to chloroform and TFE solutions, respectively, destroyed the β-structure. A random copolymer of α-isobutyl-L -aspartate with β-alanine was also prepared by polycondensation reaction. The copolymer apparently did not form an ordered structure in the solid state or in solution.     

Preparation and characterization of optically active and organosoluble poly(amide‐imide)s from polycondensation reaction of N,N′‐(4,4′‐sulphonediphthaloyl)‐bis‐L‐isoleucine diacid with aromatic diamines

3,3′,4,4′‐Diphenylsulfonetetracarboxylic dianhydride (1) was reacted with L ‐isoleucine (2) in acetic acid and the resulting imide‐acid (3) was obtained in high yield. The diacid chloride (4) was prepared from the diacid derivative (3) by reaction with thionyl chloride. The polycondensation reaction of diacid chloride (4) with several aromatic diamines such as 4,4′‐sulfonyldianiline (5a), 4,4′‐diaminodiphenyl methane (5b), 4,4′‐diaminodiphenylether (5c), p‐phenylenediamine (5d),m‐phenylenediamine (5e), 2,4‐diaminotoluene (5f) and 4,4′‐diaminobiphenyl (5g) was performed by two conventional methods: low temperature solution polycondensation and short period reflux conditions. In order to compare conventional solution polycondensation reaction methods with microwave‐assisted polycondensation, the reactions were also carried out under microwave conditions with a small amount of o‐cresol that acts as a primary microwave absorber. The reaction mixture was irradiated for 6 min with 100% of radiation power. Several new optically active poly(amide‐imide)s with inherent viscosity ranging from 0.23 to 0.41 dl/g were obtained with high yield. All of the earlier polymers were fully characterized by IR, elemental analyses and specific rotation techniques. Some structural characterizations and physical properties of these new optically active poly(amide‐imide)s are reported. Copyright © 2005 John Wiley & Sons, Ltd.     

Aromatic rigid chain copolymers. I. Synthesis,structure, and solubility of phenyl-substituted para-linked aromatic random copolyamides

Four 2,5-biphenylene based difunctional condensation monomers, such as 2,5-diphenyldicar-boxylic acid or phenylterephthalic acid (PTA), 2,5-bis(carbonylimino-4-benzoic acid)biphenyl (2,5-BCIBABP), 2,5-diaminobiphenyl hydrochloride (2,5-DABP.HCl) and 2,5-bis(iminocarbonyl-4-benzoic acid)biphenyl (2,5-BICBABP), have been synthesized and characterized. These monomers were polymerized in combination with terephthalic acid (TA) and p-phenylenediamine (PPD) via the phosphorylation reaction to prepare a series of phenyl-substituted random copolyamides having all amide groups attached to para-positions of the benzene rings. All the copolyamides have been characterized by solubility, solution viscosity, and by differential scanning calorimetry (DSC). Some of these copolyamides have unusual solubility in organic solvents such as N,N-dimethylacetamide (DMAc) and N-methyl-2-pyrrolidinone (NMP) containing dissolved lithium chloride. A few copolyamides were tested for lyotropic behavior and found to form anisotropic solutions at critical concentrations in organic solvents. A randomly distributed unsymmetrical phenyl substituent on the benzene ring of para-oriented wholly aromatic polyamides dramatically changes the solubility and melting point. The phenyl substituent on a terephthalic acid unit is more efficient in decreasing melting point and increasing solubility in organic solvents of aromatic polyamides than the one on a p-phenylenediamine unit. However, the former also introduces a more flexible link in the extended polyamide chain.     

Synthesis of ordered copolyamides by the interfacial polycondensation of the hydrolyzate of bisimidazoline with diacid chloride

Ordered copolyamides were prepared by the interfacial polycondensation of the hydrolyzate of bisimidazoline in the aqueous solution with diacid chloride in chloroform solution; bisimidazolines used were 1,4-bis(imidazoline-2-yl)butane and 1,4-bis(imidazoline-2-yl)-octane; diacid chlorides used were adipoyl chloride, sebacoyl chloride, and terephthaloyl chloride. The aqueous solutions of the hydrolyzates of bisimidazolines were prepared by heating the aqueous solutions of imidazolines at 70°C. It was shown by infrared spectra and paper electrophoresis of the hydrolyzates that bisimidazolines were hydrolyzed to give quantitatively diamines containing amides linkages of the type H₂N(CH₂)₂NH-CORCONH(CH₂)₂NH₂. The regularity in the sequence of the copolyamide of nylon 26 and nylon 2T prepared from the hydrolyzate of 1,4-bis(imidazoline-2-yl)butane and terephthaloyl chloride was studied by NMR spectrometry: it was concluded that the copolyamide was highly ordered.     

Synthesis and characterization of fluorine-containing polyamides derived from 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane by direct polycondensation

A fluorine-containing diamine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (BAPPH) ( II ), was synthesized in two steps on condensation of 2,2-bis(4-hydroxyphenyl)hexafluoropropane with p-chloronitrobenzene in the presence of potassium carbonate, giving 2,2-bis[4-(4-nitrophenoxy)phenyl]hexafluoropropane ( I ), followed by reduction with hydrazine monohydrate/Pd—C. Fluorine-containing polyamides and copolyamides having inherent viscosities 0.41–0.88 dL g⁻¹ were prepared by direct polycondensation of BAPPH with various aromatic diacids or with mixed diacids, by triphenyl phosphite and pyridine in N-methyl-2-pyrrolidinone (NMP). The polyamides were examined by elemental analysis, IR spectra, inherent viscosity, x-ray diffraction, solubility, DSC, and TGA. The diffractogram showed that the polyamides were crystalline except IVb , IVc , IVf , and Vc . Almost all polyamides were soluble in polar aprotic solvents. The polymers obtained from BAPPH lost no mass below 350°C, with 10% loss of mass being recorded above 467°C in nitrogen. These aromatic polyamides had glass transition temperatures in the 221–253°C range. © 1996 John Wiley & Sons, Inc.     

13N-NMR spectroscopy. XXXV. Sequence analysis of alternating and random copolyamides made up of aliphatic and aromatic ω-amino acids

Alternating copolyamides of various ω-amino acids were synthesized by base-catalyzed polycondensation of N-isothiocyanatoacyl ω-amino acids in solution. Derivatives of the following amino acids were used: glycine, β-alanine, γ-aminobutyric acid, δ-aminovaleric acid, ε-aminocaproic acid, D ,L -β-aminobutyric acid, trans-4-aminocyclohexane 1-carboxylic acid, 4-aminophenyl acetic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, 3-amino-4-methyl benzoic acid, and 4-amino-3-methyl benzoic acid. The base-catalyzed polycondensation at lower temperatures gave purer products than the bulk condensation at 180–200°C. ¹³C-NMR and natural-abundance ¹⁵N-NMR spectra measured in trifluoroacetic acid demonstrate that in most cases undisturbed alternating sequences were obtained. Strong neighboring residue effects and long-range sequence effects were found in the ¹⁵N-NMR spectra, and structure/shift relationships are discussed. The sequences of copolyamides obtained by copolymerizations of lactams or β-amino acid N-carboxyanhydrides were investigated by both ¹⁵N-NMR and ¹³C-NMR spectroscopy. ¹³C-NMR spectroscopy was found to be more useful if the copolyamides consist of ω-amino acid units of different chain length. However, ¹⁵N-NMR spectroscopy is more suited if the monomer units differ exclusively by their substituents.     

Synthesis of copolyamides based on ε-caprolactam and AH salt in the presence of cationic resin

Copolyamides based on ε-caprolactam and AH salt were prepared by copolymerization of various combinations of ε-caprolactam and AH salt in the presence of a cationic resin. In terms of adhesivity towards metals they have proved their superiority over nylon 6, nylon 6, 6, and the copolyamides of ε-caprolactam and AH salt, prepared in presence of water. Adhesive property of the copolyamide was found to be increased with increasing proportion of AH salt in the combinations. ε-Caprolactam (1 part) and AH salt (5 parts) in presence of a cationic resin (0.55%) were copolymerized to give a best performing copolyamide: yield 93%, mp 232°C, relative viscosity 2.42, and shear tensile strength 620 kg/in.²     

Heterocycles with a Bridged Nitrogen Atom. 13. An Anomalous Example of the Sulfonating Action of Dimethyl Sulfate During an Attempt at the Methylation of 5-Aminoindolizine. Crystal Structure of Methyl 5-Morpholyl-2-(p-nitrophenyl)indolizine-1-sulfonate

The reaction of 5-morpholino-2-(p-nitrophenyl)indolizine with dimethyl sulfate gives the sulfonation product - methyl 5-morpholyl-2-(p-nitrophenyl)indolizine-1-sulfonate. Its structure was proved by X-ray crystallographic analysis.