Reaction Of Pyromellitic Dianhydride Research Articles

Research of the Reaction of Pyromellitic Dianhydride with [3-(Aminomethyl)bicyclo[2.2.1]hept-2-yl]anilines by Calorimetric Method

Research of the Reaction of Pyromellitic Dianhydride with [3-(Aminomethyl)bicyclo[2.2.1]hept-2-yl]anilines by Calorimetric Method

Synthesis and physicochemical investigation of imide‐functionalized silica nanocomposites

AbstractThe incorporation of inorganic nanoparticles into polymers have gained significant attention to improving functional properties. The ultimate nanocomposite behaviors are influenced by many parameters, such as microstructural distribution that are produced during the treatment process. Herein, a hybrid material integrating a modified network into a polyimide PI matrix was produced via the sol–gel method by the reaction of pyromellitic dianhydride, 4, 4‐oxydianaline, and 1, 5‐diaminonaphthalene to synthesize copolyimides nanocomposite. The modified polyimide and unmodified polyimide silica (SiO2) nanoparticles were incorporated in the polyimide matrix to have polyimide silica nanocomposite. In modified silica nanoparticles, 3‐aminopropyltriethosilane was introduced to have better compatibility among inorganic–organic hybrid with similar chemical contact due to their flexible alkyl group. The surface morphology or structure of silica and polyimide was affirmed by scanning electron microscopy, Fourier transforms infrared spectroscopy confirmed the synthesis of pure polyimide, unmodified polyimide, and modified polyimide silica via presence and absence of certain peaks. Thermogravimetric analysis (TGA) results showed high thermal stability of nanocomposites as silica content increases. In contrast to unmodified silica, the modified silica provides more thermal stability to the nanocomposites. Dynamic mechanical analysis was used to investigate the tensile stress of pure polyimide, unmodified, and modified silica nanocomposites. Thermal stability, storage modulus, and moisture absorption of these hybrid materials were improved with silica nanoparticles. The TG mass spectrum confirms the successful synthesis of modified silica networks. The substituted silica nanoparticles show higher mechanical toughness and storage in modified compared to unmodified silica nanocomposite, which exhibits stronger binding attraction between silica nanoparticles and polyimide matrix.

Thermal stability and dynamic mechanical thermal analysis of epoxy thermosets possessing N,N′-disubstituted pyromellitimide units

In this work, three epoxy resins including diglycidyl ethers of N,N′-bis(2-hydroxyethyl)pyromellitimide (DIDGE), bisphenol-A (BADGE), and polyethylene glycol (PEDGE) were isothermally cured by an amine curing agent possessing N,N′-disubstituted pyromellitimide units (denoted by DIDAM). DIDGE resin was synthesized from the reaction of N,N′-bis(2-hydroxyethyl)pyromellitimide with an excess of epichlorohydrin. Also, DIDAM curing agent was prepared from the reaction of pyromellitic dianhydride with an excess of ethylene diamine. Completion of the isothermal curing processes was approved by both Fourier transform-infrared spectroscopy and non-isothermal differential scanning calorimetry (DSC). The DSC traces showed only the phase transitions related to the thermal degradation of the resulting thermosets. According to the thermogravimetric analyses, the DIDGE/DIDAM thermoset showed higher thermal stability at temperatures above 425 °C than the other two thermosets. While BADGE/DIDAM and PEDGE/DIDAM thermosets showed about 70% weight loss in the thermal range of 400–850 °C, DIDGE/DIDAM thermoset was encountered with only about 40% weight loss. The glass transition temperatures (Tg ) of the resulting thermosets were determined using tan δ vs temperature plots obtained from dynamic mechanical thermal analysis. The Tg values of BADGE/DIDAM, DIDGE/DIDAM, and PEDGE/DIDAM thermosets were found to be 211 °C, 189 °C, and 81 °C, respectively.

Structural, thermal and mechanical properties of polymer nanocomposites based on organosoluble polyimide with naphthyl pendent group and layered double hydroxide

In this study, a soluble aromatic polyimide (PI) with naphthyl pendent group was initially synthesized by the reaction of pyromellitic dianhydride (PMDA) with 5-methyl- N,N-bis(4-nitrophenyl)naphthalen-1-amine. Then, via co-precipitation reaction of zinc nitrate hexahydrate and chromium nitrate nonahydrate, Zn/Cr-layered double hydroxide (LDH) was synthesized using hydrothermal techniques. Finally, different novel nanocomposites (NCs) based on PI and Zn/Cr-LDH (1, 2, 4 wt%) were produced through in situ polymerization. The resulting materials were characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, thermogravimetry analysis (TGA), field emission scanning electron microscopy, transmission electron microscopy, and mechanical testing. According to the TGA results, the prepared NCs showed high thermal stability at higher temperature due to the good dispersion and homogeneity of Zn/Cr-LDH in polymeric matrix. Consequently, the mechanical properties of the synthesized NCs were enhanced by the incorporation of 2 wt% Zn/Cr-LDH in the polymer matrix.

Synthesis, characterization and properties of aromatic copolyimides containing Bi-benzimidazole moiety

A new aromatic heterocyclic diamine monomer, 2,2-bis (4’-aminophenyl)- 5,5-bi-1H-benzimidazole (BAPBBI), was synthesized via a one-step reaction of 3,3’,4,4’-biphenyltetramine and p-aminobenzoic acid in polyphosphoric acids with the high yield and purity. FTIR, 1H NMR, 13C NMR, mass spectra and elemental analysis were employed to confirm the chemical structures. A series of copolyimide films containing the bi-benzimidazole moieties were prepared by the reaction of pyromellitic dianhydride (PMDA), 4,4’-oxydianiline (ODA) and BAPBBI with various molar ratios. The combination of polybenzimidazole and polyimide by introducing BAPBBI into the main chains brings the highly rigid structure and the enhanced macromolecular interactions, resulting in the enhancement in the thermal stability and the mechanical properties. For instance, these polyimides are endowed with a higher glass transition temperature of 408–438 °C and an initial thermal decomposition of 550–580 °C. They exhibit a strong tensile strength of 123–233 MPa, and a tensile moduli of 2.66–12.84 GPa without post stretching. Meanwhile the stretched films at 450 °C exhibited the enhanced mechanical properties with the tensile strength of 195–554 MPa and the tensile modulus of 4.69–38.57 GPa.

Preparation and characterization of new optically active poly(amide-imide)s and poly(ester-imide)s containing calix[4]arene units

This article describes the synthesis and characterization of new optically active polymers containing upper rim calix[4]arene from the polycondensation reaction of 5,11,17,23-tetra-tert-butyl-25,27-bis[(4-aminobenzyloxy)-6,28-dihydroxy] calix[4]arene with N,N′-pyromellitoylimido-bis-L-alanine diacid chloride (6a) and N,N′-pyromellitoylimido-bis-L-phenyl alanine diacid chloride (6b). This optically active diacidchlorides 6a and 6b have been prepared from the reaction of pyromellitic dianhydride with two chiral amino acids, alanine and phenyl alanine. The chiral poly(amide-imide)s and poly(ester-imide)s obtained in good yield and moderate inherent viscosity. All the polymers have been fully characterized by FTIR, 1H NMR spectroscopy and elemental analysis.

Neutral Red Adsorption onto Modified Chitosan: Effect of pH and Temperature

The purpose of the research was to investigate the effects of temperature, initial pH, initial concentration, and contact time on the biosorption of neutral red (NR) by modified chitosan using a batch technique. The modified chitosan was prepared by grafting poly (amic acid), which was obtained via reaction of pyromellitic dianhydride (PMDA) and L-arginine, onto the surface of cross-linked chitosan. The NR sorption process was evaluated at 25°C, 35°C, and 45°C. Results showed that the modified chitosan had a good capacity for biosorption of NR. The kinetic behavior was described by the pseudo-second-order model. The experimental isotherms obtained were fit better with the Langmuir model than with the Freundlich model. Thermodynamic parameters and were calculated using the Van’t Hoff equation, and the results showed that NR sorption by modified chitosan was an endothermic and spontaneous process.

Biosorption of methylene blue from aqueous solution by poly(amic acid)‐modified chitosan

The purpose of the research was to investigate effects of temperature, initial pH, initial concentration, and contact time on the biosorption of methylene blue (MB) by modified chitosan using a batch technique. The modified chitosan was prepared by grafting poly (amic acid), which was obtained via reaction of pyromellitic dianhydride (PMDA) and l‐arginine, onto the surface of cross‐linked chitosan. The MB sorption process was evaluated at 25, 35, and 45°C. Results showed that the modified chitosan had a good capacity for biosorption of MB. The kinetic behavior was described by pseudo‐second‐order model. The experimental isotherms obtained were fitted better with Langmuir model than Freundlich model. According to the Langmuir equation, the maximum uptake capacity (qm) for MB was 392.16 mg g−1. Thermodynamic parameters and were calculated using the Van't Hoff equation, and results showed that MB sorption by modified chitosan was an exothermic and spontaneous process. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 1180–1186, 2014

Poly(amide-imide)s obtained from 3,5-diamino-N-(thiazol-2-yl)-benzamide and dicarboxylic acids containing various amino acid units

This study reports a green approach toward the synthesis of novel optically active poly(amide-imide)s (PAI)s bearing thiazole moiety, which was formed by the polycondensation reaction of 3,5-diamino- N-(thiazol-2-yl)benzamide and various diacids containing natural amino acids in molten tetrabutylammonium bromide. Diamine monomer was synthesized by the reduction of 3,5-dinitro- N-(thiazol-2-yl)benzamide in methanol using iron oxide hydroxide as a catalyst. This catalyst can rapidly reduce the sulfur and azo-containing aromatic nitro compounds to the corresponding amines in high yield by employing hydrazine hydrate as a hydrogen donor. Chiral diacid monomers were synthesized in high yield through the reaction of pyromellitic dianhydride and amino acids (l-isoluecine, S-valine, S-methionine, and l-phenylalanine) in acetic acid. The direct polymerization reactions of these monomers provided a series of new optically active PAIs with inherent viscosities in the range of 0.20–0.28 dL g−1. The obtained polymers were characterized by Fourier-transformed infrared spectroscopy, specific rotation measurements, and the representative of them by proton nuclear magnetic resonance and elemental analysis techniques.

Synthesis, crystal structure and electrochemical properties of [Co(phen)3] · (H3btec) · (H2btec)0.5 · DMF · 6H2O

A new complex [Co(phen)3] · (H3btec) · (H2btec)0.5 · DMF · 6H2O (1) (H4btec = 1,2,4,5-Benzenetetracarboxylic acid, phen = 1,10-phenanthroline, DMF = dimethylformamide) was synthesized by the reaction of pyromellitic dianhydride, phen · H2O and CoSO4 · 7H2O. Complex 1 crystallizes in the triclinic system, space group P-1 with a = 11.8123(14) A, b = 13.0356(16) A, c = 17.575(2) A, α = 91.461(2)°, β = 101.347(2)°, γ = 99.830(2)°, FW = 1159.94, Z = 2, V = 2609.5(5) A3. X-ray crystal structural determination indicates that the Co(II) ion is octahedral coordinated by six nitrogen atoms of three phenanthroline ligands. The [Co(phen)3]2+ cation engages its phen ligands in π-π interactions with H2btec anion. Extensive hydrogen bonding interactions occur between water molecules, DMF, H3btec and H2btec anions. The highly-crystalline compounds 1, which are insoluble in water as well as common organic solvents, have been characterized in the solid-state by elemental analysis, thermogravimetric analysis and IR spectra. Moreover, the study of the electrochemistry of complex 1 was carried out by using cyclic voltammetry. It revealed that the Co(II) complex exhibits a quasi-reversible one-electron redox process.

Excited states with the hydrogen bond in the reaction of aromatic dianhydrides with diamines

Polycondensation of aromatic dianhydrides and diamines is widely used for the synthesis of heatresis� tant polymers, polyimides (1); however, the mecha� nism of its elementary steps has not been adequately studied. An important problem to be solved concerns the role of the hydrogen bond in proceeding of this reaction. It is expedient to consider this problem in terms of electron excitation in the elementary chemi� cal reaction (2) with the use of specific mechanisms of the electron-proton effect (3, 4). It is suggested that the interaction of the π�electron systems of the diamine (donor) and dianhydride (electron acceptor) in the excited state through hydrogen bonding leads to a considerable decrease in the energy of the electronic level and its displacement into the thermal energy range (less than 1 eV). The optical charge transfer (CT) transitions for complexes of aromatic diamines and dianhydrides are observed in the visible spectral range 13 000-21000 cm -1 (5). Recently (2), we put forward the idea that the reaction states have the sig� nificance of equilibrium electronically excited states with energies close to the experimental activation energies Ea. For the reaction of pyromellitic dianhy� dride (PM) with mphenylenediamine ( mPD), the activation energy is 6-8 kcal/mol (6). In this context, a problem arises to theoretically estimate the energy of equilibrium excited states and, simultaneously, to determine the role of the electron-proton effect, as a factor of chemical catalysis, due to the interplay of the electron donor-acceptor interaction and hydrogen bond that occurs in electron excitation events.

Ionic liquid catalyzed synthesis and characterization of heterocyclic and optically active poly (amide-imide)s incorporating l-amino acids

N,N'-pyromelliticdiimido-di-L-alanine (1), N,N'-Pyromelliticdiimido-di-L-phenylalanine (2), and N,N'-Pyromelliticdiimido-di-L-leucine (3) were prepared from the reaction of Pyromellitic dianhydride with corresponding L-amino acids in a mixture of glacial acetic acid and pyridine solution (3/2 ratio) under refluxing conditions. A series of poly (amide-imide)s containing L-amino acids were prepared from the synthesized dicarboxylic acids with two synthetic aromatic diamines in an ionic liquid (IL) as a green, safe and eco-friendly medium and also reactions catalysis agent. Evaluation of data shows that IL is the better polyamidation medium than the reported method and the catalysis stand on the higher inherent viscosities of the obtained PAIs and the rate of polymerizations beyond the greener reaction conditions and deletion of some essential reagents in conventional manners. Characterization were performs by means of IR, MS and (1)H NMR spectroscopy, elemental analysis, specific rotation, thermogravimetric analysis and differential scanning calorimetric techniques. Molecular weights of the obtained polymers were evaluated viscometrically, and the measured inherent viscosities were in the range 0.43-0.85 dL/g. These polymers were readily soluble in many organic solvents. These polymers still kept good thermal stability with glass transition temperatures in the range of 94-154°C, and the decomposition temperature under the nitrogen atmosphere for 10% weight-loss temperatures in excess of 308°C.

Synthesis and Characterization of New Optically Active Poly(amide-imide)s Based on N,N′-(Pyromellitoyl)-bis-L-Amino Acids and 1,3,4-Oxadiazole Moieties

New optically active poly(amide-imide)s derived from chiral N,N′-(pyromellitoyl)-bis-L-amino acids (3a–f) and 2,5-bis(4-aminophenyl)-1,3,4-oxadiazole (BAO) (8) were synthesized by direct polycondensation. Chiral N,N′-(pyromellitoyl)-bis-L-amino acids were obtained by the reaction of pyromellitic dianhydride with two equimolar of L-alanine (2a), L-valine (2b), L-leucine (2c), L-isoleucine (2d), L-phenyl alanine (2e) and L-2-aminobutyric acid (2f) in acetic acid. The polycondensation reaction proceeded through the in situ formation of an Vilsmeier adduct by dissolving tosyl chloride (TsCl) in a mixed solvent of pyridine and DMF. The resulting thermally stable poly(amide-imide)s were obtained in good to high yields and inherent viscosities ranging between 0.31 and 0.55 dl/g. The structures of the new polymers were confirmed by elemental analysis and spectral methods (FT-IR, 1H-NMR). Optical activity and thermal behavior investigated by polarimetric measurements and thermogravimetric analysis, respectively.

Preparation and cured properties of diallyl phthalate resin modified with epoxy resin and allyl ester compound having carboxylic acid

AbstractAn epoxy resin was blended with a diallyl phthalate resin to improve the adhesive properties and the fracture toughness. A compatibilizer was used to reduce the decrease in heat resistance. An allyl ester compound [1,4‐diallyloxycarbonyl‐2,5‐benzenedicarboxylic acid (DAPY)], which reacted with the diallyl phthalate resin and epoxy resin to have allyl groups and carboxylic acids on the end of the molecular chain, was synthesized as a compatibilizer by the reaction of pyromellitic dianhydride with allyl alcohol. These blends were cured with dicumyl peroxide and triethylamine. By modification with the epoxy resin and DAPY, the lap shear adhesive strength to steel increased up to about 3 times that of the diallyl phthalate resin. These results suggest that the secondary hydroxyl group generated by the addition reaction of the epoxy resin and DAPY and the secondary hydroxyl group existing in the molecular chain of the epoxy resin formed hydrogen bonds with the hydroxyl group of water existing on a metal surface, and as a result, the adhesive strength to metal such as steel increased. The fracture toughness of the diallyl phthalate resin was increased by modification with the epoxy resin. The reason for this result was that the flexibility increased because the crosslinking density became small by modification with the epoxy resin. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Synthesis and characterization of chemically cross-linked polyimide–siloxane hybrid films

Abstract Chemically cross-linked polyimide and silica hybrid films were prepared through the sol–gel processing. PI matrix was prepared by the reaction of pyromellitic dianhydride with a mixture of diamines e.g., oxydianiline and 2,5-diaminohydroquinon (2,5-DAHQ) to include pendant hydroxyl groups on the chain. These groups were reacted further with isocyanatopropyltriethoxysilane. An appropriate amount of tetraethoxysilane was then added and the sol–gel process was carried out to condense ethoxy groups from both types of silanes thus producing chemically bonded composite films. The films with different silica contents were evaluated by a variety of techniques including FTIR, 29Si NMR, SEM, tensile, thermal, mechanical and thermogravimetric analyses. The chemical interaction between the phases brought about an intimate dispersion of the two phases, which resulted in the formation of nano-sized co-continuous domains. The tensile modulus of such films was higher and thermal expansion coefficient was much lower than those with similar silica contents without inter-phase bonding.

Microwave‐assisted synthesis and characterization of heterocyclic, and optically active poly(amide‐imide)s incorporating L‐amino acids

AbstractN,N′‐Pyromelliticdiimido‐di‐L‐alanine (1), N,N′‐pyromelliticdiimido‐di‐L‐phenylalanine (2), and N,N′‐pyromelliticdiimido‐di‐L‐leucine (3) were prepared from the reaction of pyromellitic dianhydride with corresponding L‐amino acids in a mixture of glacial acetic acid and pyridine solution (3/2 ratio) under refluxing conditions. The microwave‐assisted polycondensation of the corresponding diimide‐diacyl chloride monomers (5–7) with 4‐phenyl‐2,6‐bis(4‐aminophenyl) pyridine (10) or 4‐(p‐methylthiophenyl)‐2,6‐bis(4‐aminophenyl) pyridine (12) were carried out in a laboratory microwave oven. The resulting poly(amide‐imide)s were obtained in quantitative yields, and they showed admirable inherent viscosities (0.12–0.55 dlg−1), were soluble in polar aprotic solvents, showed good thermal stability and high optical purity. The synthetic compounds were characterized by IR, MS, 1H NMR, and 13C NMR spectroscopy, elemental analysis, and specific rotation. Copyright © 2008 John Wiley & Sons, Ltd.

Synthesis and characterization of new optically active poly(azo-ester-imide)s via interfacial polycondensation

N,N'-Pyromelliticdiimido-di-L-amino acids (1a-1d) were prepared from the reaction of pyromellitic dianhydride with the corresponding L-amino acids in a solution of glacial acetic acid/pyridine (3:2) at refluxing temperature. 4,4'-sulfonyl bis(4,1-phenylene) bis(diazene-2,1-diyl) diphenol, 4,4'-oxy bis(4,1-phenylene) bis(diazene-2,1-diyl) diphenol and 4,4'-methylene bis(4,1-phenylene) bis(diazene-2,1-diyl) diphenol, were prepared from 4,4'-diamino diphenyl sulfone, 4,4'-diamino diphenyl ether, 4,4'-diamino diphenyl methane, sodium nitrite and phenol following the general procedure of diazo coupling. Interfacial polycondensation method was used to prepare the corresponding poly(azo-ester-imid)s (PAEI(1-12)) in biphasic solution of water/dichloromethane. The resulting polymers (PAEIs) have been obtained in high yields having good inherent viscosities (0.32-0.57 dl g(-1)), optical activities and thermal stabilities.

The effect of curing conditions and ageing on the thermo-mechanical properties of polyimide and polyimide–silica hybrids

The effect of curing conditions and ageing on the thermo-mechanical properties of polyimide and its ceramers has been studied. Polyamic acid (PAA), a polyimide precursor, was prepared by the well known reaction of pyromellitic dianhydride and oxydianiline in dimethylacetamide as solvent. The silica network was developed in PAA solution by hydrolysis and condensation of tetraethoxysilane. The pure PAA films and those with 25 wt% silica content were imidized by six different curing protocols involving both step-wise and isothermal heatings. The dynamic mechanical thermal (DMTA) and thermal mechanical analyses (TMA) were performed on the pure and ceramer films cured under the different imidization conditions. The data for the mechanical properties were obtained for the same films left over for a year. The variations of storage and loss moduli and the glass transition temperature associated with α-relaxation and the linear thermal expansion coefficient have been explained in terms of degree of imidization and the effect of silica network densification under different conditions as a result of imidization and ageing.

Polymer modified biomass of baker's yeast for treating simulated wastewater containing nickel and lead

AbstractBaker's yeast was cross‐linked by glutaraldehyde and then modified by grafting with poly(amic acid), which was prepared via reaction of pyromellitic dianhydride (PMDA) and arginine at 50°C. The morphology of the pristine, cross‐linked, and modified biomass was observed by microscope. The presence of poly(amic acid) on the biomass surface was verified by X‐ray photoelectron spectroscopy (XPS) analyses. Due to the high density of the functional groups on the modified biomass surface, the metal adsorption capacity for nickel and lead increased significantly, especially when the carboxylic acid groups were converted into carboxylate ions using NaOH. The adsorption process for nickel and lead adsorption followed the pseudo‐second‐order kinetics. The metal adsorption data were fitted with the Langmuir and Freundlich isotherms with the former having a better fit. Using the Langmuir adsorption isotherm, the maximum uptakes for nickel and lead were found to be 0.848 and 0.980 mmol g−1 respectively which were about 15 and 11 times higher than the prisitine biomass. In the simulated wastewater containing 0.400 mmol l−1 of Ni2+ and Pb2+, the metal adsorption capacity of Ni2+ and Pb2+ reached 0.365 mmol l−1 and 0.390 mmol l−1, respectively. The metal ions loaded biomass was regenerated using Ethylene Diamine Tetraacetic Acid (EDTA) solution and used repeatedly over four cycles with little loss of uptake capacity. Copyright © 2007 John Wiley & Sons, Ltd.

Biomass grafted with polyamic acid for enhancement of cadmium(II) and lead(II) biosorption

In this study, a simple method was used to prepare modified biomass to improve its adsorption capacity for Cd 2+ and Pb 2+. The modified biomass of baker’s yeast was obtained by grafting polyamic acid, which was prepared via the reaction of pyromellitic dianhydride (PMDA) and lysine, onto the surface of glutaraldehyde-pretreated biomass at 50 °C for 3 h. The presence of polyamic acid on the biomass surface was verified by Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS), the morphologies of the biomass before and after modification were observed by microscope. Due to the high density of the carboxyl and amide groups on the biomass surface, the uptake for Cd 2+ and Pb 2+ showed a significant increase. According to Langmuir adsorption isotherm, the maximum uptake for Cd 2+ and Pb 2+ were 95.2 and 204.5 mg g −1, which were 15- and 11-fold for that obtained on the uncontaminated biomass. The kinetics for Cd 2+ and Pb 2+ adsorption followed the pseudo-second-order model. The results of FTIR and XPS revealed that carboxyl, amide, and hydroxyl groups on the biomass surface were involved in the adsorption of Cd 2+ and Pb 2+.