Benzophenone Tetracarboxylic Acid Dianhydride Research Articles

Fabrication of thermally resistant and mechanically flexible polyimide foams with anisotropic pore structures for thermal insulation and irradiation tolerance applications

Flexible polyimide foams (PIFs) demonstrate a great potential for applications in the fields of thermal insulation, flame retardancy and irradiation tolerance. In this work, mechanically flexible PIFs with anisotropic pore structure were prepared by adopting the copolymerization strategy and microwave-assisted foaming process. The copolymerization reaction was conducted to synthesize polyester ammonium salt (PEAS) precursors using 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA) as dianhydride, 4,4′-diaminodiphenyl ether (ODA) and 4,4′-diaminodiphenyl sulfone (DDS) as the copolymerized diamines; afterwards, PEAS powders with particle sizes ranging from 100 to 300 μm were obtained by drying, crushing and sieving treatments, which were used as the feedstock for “bottom-up” microwave-assisted foaming and thermal imidization process, thereby leading to the formation of PIFs with regular three-dimensional near-spherical pores in vertical direction (parallel to the pore growth direction) and the aligned ellipsoidal strip-like pore structure in horizontal direction. The directional growth of foam pores resulted in anisotropic mechanical flexibility and thermal insulation performance. Moreover, PIFs possessed excellent thermal stability and flame retardancy with the initial thermal degradation temperature higher than 545 °C and limited oxygen index up to 58.8%. The PIFs exhibited exceptional thermal insulation performance with thermal conductivity values ranging from 0.0276 to 0.0517 W/(m·K) between 25 and 300 °C. Additionally, the PIFs demonstrated excellent irradiation tolerance, with the mechanical and thermal stability retention rate being above 96% after the irradiation experiment (radiation dosage: 1.15 × 105 Gy) using 60Co source. Thus, lightweight PIFs with superior high temperature thermal insulation performance, flame retardancy and irradiation tolerance were successfully prepared, which showed potential applications in aerospace, medical and nuclear power sectors.

Lightweight thermo- and heat-resistant composite materials based on polyimide foam

A prepolymer foaming composition based on 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride methyl ester and diamines: 4,4'-diaminodiphenylmethane and m-phenylenediamine for the production of high-temperature polyimide foam (PIF) is proposed. The p ossibility o f u sing P IF a s a b inder f or c omposite materials (foam composites) reinforced with carbon or organic fibers with low density (0.4–1.1 g/cm3) a s a result of foaming of the binder during the formation of the foam composite is shown. The density and mechanical properties of the foam composite can vary within a relatively wide range depending on the volume content of the fiber and air pores. The high glass transition temperature of 260°C, combined with the high thermal stability of carbon or polyimide fibers, contributes to the retention of the mechanical properties of such composites at elevated temperatures. The temperature of the start of mass loss of the foam composite must be at least 550°C, and it depends on the type of fibrous material. The combination of the excellent thermal and mechanical properties of lightweight PIF composites, together with the exceptional fire resistance of polyimide materials, may provide new applications in advanced aircraft and shipbuilding technologies.

The effects of long and bulky aromatic pendent groups with flexible linkages on the thermal, mechanical and electrical properties of the polyimides and their nanocomposites with functionalized silica.

A novel diamine bis(4-aminophenyl)bis{3,4[(4-(8-quinolyloxymethyl carbonyl)]}methane, containing two long/bulky aromatic pendent chains was synthesized by incorporating aromatic and hetero aromatic groups with flexible linkages. Flexible, stretchable, thermally stable and processable polyimides were prepared by reacting this newly synthesized diamine with commercial tetracarboxylic acid dianhydrides like 3,3′,4,4′-benzophenone tetra carboxylic acid dianhydride (BTDA) and 4,4′-(4,4′-isopropylidenediphenoxy)diphthalic Anhydride (BPADA). Nanocomposites of polyimides were prepared using aromatic amine functionalized silica as a filler by solution casting method. The current work investigates the effects of incorporating long/bulky aromatic side chains and flexible linkages on the thermal, mechanical, electrical and optical properties of the polyimides and nanocomposites. The polyimides showed good thermal stability (T10% = 364 & 388), high flame resistance, low glass transition temperatures (Tg = 130 °C & 156 °C), very low dielectric constants (2.5 & 2.8 at 1 MHz) and good optical transparency. The neat polyimides displayed good elongation at break (133–155%) but possessed low tensile strength. The chemically imidized polyimides showed good solubility in low and high boiling solvents. Nanocomposites of polyimides based on aromatic amine functionalized silica exhibited enhanced properties with T10% values varying between 409–482 °C, Tg between 165–280 °C and higher dielectric constants (3–5.7 at 1 MHz).

An investigation on curing rheokinetics of a nadic end-capped MDA-BTDA-ODA copolyimide resin by dynamic mechanical analysis

Abstract The curing behavior of a nadic end capped MDA-BTDA-ODA copolyimide resin was investigated using dynamic mechanical analysis in the shear mode. The studied copolyimide consists of 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride (BTDA) with a 50:50 M combination of 4,4′-diaminodiphenylmethane (MDA) and 3,4′-oxydianiline (ODA) monomers. The effects of curing temperature and time on the rheological properties of the resin were examined. At the beginning of the network formation process, an increase in the storage modulus, loss modulus and complex viscosity was observed. The gelation temperature, Tgel, was determined from the intersection points of the temperature-dependent storage and loss moduli curves. It was found that the rate of gelation of the resin was increased with increasing temperature. In terms of mechanical curing condition, the kinetics of isothermal network formation process at different isothermal curing temperatures were monitored by using Kamal-Sourour model. The model fitted well with experimental data. Therefore, mechanical conversion at different temperatures can be well predicted by the kinetics data.

Phase state diagram of a poly(amic acid)–solvent–nonsolvent system

Phase behavior and structure formation was studied using optical interferometry, nephelometry, and refractometry in the polymer–solvent–nonsolvent system for DMF solutions of two poly(amic acids): based on 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride and meta-phenylenediamine (PAA-1) and pyromellitic acid dianhydride and 4,4′-oxydianiline (PAA-2). Distilled water and its mixtures with DMF were used as a nonsolvent. According to the results of the study, isothermal cross sections of the phase state diagram in the threecomponent system were plotted, the position of the critical point, the spinodal, and the conodes were determined, the movement of the figurative points in the system was traced depending on the nonsolvent composition.

Synthesis and characterization of novel high temperature structural adhesives based on nadic end capped MDA-BTDA-ODA copolyimide

A series of novel copolyimide structural adhesives were synthesized using 4,4′-diaminodiphenylmethane (MDA), 3,4′-oxydianiline (ODA) and 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride (BTDA) as co-monomers, and nadic anhydride as an end cap reagent. The adhesives with different MDA and ODA contents were examined in terms of their structure, thermal stability, mechanical properties, and adhesive performance. They have glass transition temperatures (Tg) about 400 °C, with thermal stability up to 500 °C. The effect of diamine monomer compositions on adhesion performance and processability of the copolyimides were studied. The copolyimides exhibited adhesion strength up to 16.3 MPa at room temperature. Nadic end capped MDA-BTDA-ODA copolyimide resins gained adjustable and controllable processability with the addition of ether bridged aromatic segments. The copolyimide adhesive with equimolar composition of MDA:ODA is distinguished form the both commercial PMR-15 and LARC RP-46 polyimides in terms of its better processability and mechanical performance.

Synthesis and Characterization of a Novel High-Temperature Structural Adhesive Based on MDA-BAPP-BTDA Co-Polyimide

A series of polyimide(PI) adhesives were synthesized from 2,2'-Bis [4-(4-aminophenoxy)phenyl] propane(BAPP), 4,4'-Diaminodiphenylmethane (MDA) and 3,3',4,4'-Benzophenonetetracarboxylic acid dianhydride (BTDA) via a two-step process. PI adhesives with different BAPP content were characterized in regard to their structure, thermal stability, mechanical properties and adhesive performance. Results showed that these PIs had excellent thermal stability, whose glass transition temperature (Tg) were around 300°C. While, superior dynamic mechanical behavior was observed, and the maximum loss factor declined with the increase of BAPP content. Single-lap shear strength of over 15.58 MPa at room temperature was obtained, and it remained high even at the temperature of 350°C. Factors that could affect bonding strength of these PI adhesives such as molar ratio of the diamine monomers, surface roughness of adherends and curing processes were investigated.

Ethynyl 말단기를 갖는 Polyisoimide 올리고머의 합성 및 이들의 경화거동에 관한 연구

Acetylenic or phenylethynyl end-capped polyisoimide oligomers ( 2500 g/mol, 5000 g/mol) based upon 4,4'-diamino diphenyl ether (4,4'-ODA)/4,4'-oxydiphthalic anhydride (ODPA) and 4,4'-ODA/3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BTDA) were synthesized by using 4-ethynylaniline (4-EA) or 4-phenylethynyl phthalic anhydride (4-PEPA) as an end capper. The incorporation of ethynyl groups were confirmed by FTIR spectroscopy. The isomerization temperature was influenced by molecular weight as well as the backbone structure of polyisoimides oligomers. Thus, polyisoimide oligomers with molecular weight of 2500 g/mol was found to be imidized at temperature lower than that for the oligomers with molecular weight of 5000 g/mol. The crosslinking reaction of ethynyl groups occurred at a higher temperature than that for the isoimide/imide isomerization reaction. These two reactions were totally or partially overlapped on the DSC thermograms for the polyisoimide oligomer end-capped with 4-EA. Kinetics of thermal imidization and crosslinking reactions for the 4,4'-ODA/ODPA polyisoimide oligomers end-capped with 4-PEPA were investigated by performing dynamic DSC experiments at heating rate of . The activation energy and pre-exponential factors were 141 kJ/mol and for the imidization reaction and 177 kJ/mol and for the crosslinking reaction, respectively.

Enhanced polyimide proportion effects on fire behavior of isocyanate-based polyimide foams by refilled aromatic dianhydride method

Lightweight and fire-resistant isocyanate-based polyimide foams (PIFs) were rapidly formed via a simple one-pot process; polymethylene polyphenylene isocyanate (PAPI) was added into a solution containing refilled aromatic dianhydride. The obtained Fourier transform infrared spectra (FT-IR) showed that the refilled 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA) reacted with isocyanate and amino groups in PIFs during the forming and postcuring process. These reactions increased the percentage of polyimide in the foams. Meanwhile, the reaction between refilled BTDA which has a higher reactivity than its derivatives and amino groups, reduced the reaction between isocyanate and amino groups. Subsequently, the generation of ureido was restrained. Thermal gravimetric analysis (TGA) and differential thermogravimetry (DTG) results presented that when the refilled BTDA dosage was increased, the percentage of polyimide and ureido were increased and reduced, respectively. However, the proportion of different ingredients in the PIFs prepared by different formulations was basically the same when the refilled BTDA dosage exceeded 50%. As such, the refilled dosage of BTDA between 50% and 60% was sufficient for this system, the refilled BTDA had extreme effects on enhancing polyimide proportion and reducing the generation of ureido. Fire resistance was characterized by limiting oxygen index (LOI) and cone calorimeter (CCT). Results showed that with the gradual increasing in polyimide proportion of the PIFs resulting from the increase in refilled BTDA dosage, their fire resistance was remarkably improved, which was mainly reflected by the following: gradual increase in LOI value, decrease in heat release rate (HRR), decrease in the peak of HRR (PHRR), decrease in total smoke production (TSP), and decrease in average specific extinction area (ASEA). Compared with the foam prepared without refilled BTDA, the foam prepared with 60% BTDA refilled dosage exhibited increased LOI value from 20.8% to 30.1%, PHRR reduction from 181.91 kW/m2 to 41.54 kW/m2, and significant reduction of HRR. The reduction in TSP and ASEA reached up to 78.2% and 83.1%, respectively. Meanwhile, when the refilled dosage of BTDA exceeded 60%, the LOI value also showed a slower increase. This change was possibly due to the residual BTDA in foams, which acted as a retardant packing role. The density of foams also increased when the post-additive dosage of BTDA was increased. Possible chemical reactions involved in this preparation method of isocyanate-based PIFs were also discussed in this paper.

Immobilization of alpha‐amylase on aminated polyimide membrane: Preparation, characterization, and properties

α‐amylase was covalently immobilized on functionalized polyimide (PI) membranes via glutaraldehyde (GA) activation. 3,3′,4,4′‐Benzophenonetetracarboxylic acid dianhydride (BTDA) and 4,4′‐oxydianline (4,4′‐ODA) based polyimide membranes were obtained via thermal imidization. Free amine groups on the surface of the polyimide membranes were generated by the amination reaction of polyimides with hexamethylenediamine (HMDA). Surface‐aminated membranes were subjected to enzyme immobilization after GA activation. Immobilization efficiency and enzyme activity of α‐amylase was examined at various pH (3.0–8.0) and temperature (15–80°C). The storage stability and reusability of immobilized α‐amylase were investigated. Immobilization yield was found as 359.53 mg per gram of modified polyimide films. Enzyme assays demonstrated that the immobilized enzyme exhibited better thermo stability than the free one. The storage stability and reusability improved by the immobilization on this enzyme support. Free enzyme lost its activity completely within 15 days. On the other hand, the immobilized enzyme retained 79.98% of its activity after 30 days. These results confirmed that α‐amylase was successfully immobilized and gained more stable character compared to the free enzyme.

Preparation and properties of KH550-Al2O3/PI–EP nanocomposite material

First, polyimide (PI)–epoxy resin (EP) polymer matrix was prepared from 3,3′-diethyl-4,4′-diamino diphenyl methane (DEDADPM), benzophenone tetracarboxylic acid dianhydride (BTDA) and epoxy resin (E-51), through thermal imide process. Then, the nanometer alumina (Al2O3) modified by the coupling agent, (3-aminopropyl)triethoxysilane (KH550), was doped into the PI–EP polymer matrix, using an in situ sol–gel method to prepare a series of KH550-Al2O3/PI–EP nanocomposite materials based on different KH550-Al2O3 contents. Fourier transform infrared spectroscopy (FTIR) indicated that in the presence of chemical reaction between poly(amic acid) and epoxy resin, an imide ring was formed, the thermal imidization reaction of the materials was completed and the KH550-Al2O3 had doped into the PI–EP polymer matrix. The heat-resistance, dielectric specification and mechanical properties of KH550-Al2O3/PI–EP nanocomposite materials were evaluated. The results showed that the decomposition temperatures were ranged between 438 and 450 °C, dielectric constant and dielectric loss were in the range of 3.32–3.71 and 1.5 × 10−3–2.5 × 10−2, respectively, and they all increased with the increase of KH550-Al2O3 content (0–10 wt%), but the shear strength first increased and then decreased, attained its maximum value of 10.64 MPa at 8 wt%, which was about 119 % higher than that of undoped material. The adhesive forces of nanocomposite materials were all at higher level (one or two levels). Thus, the overall performance of KH550-Al2O3/PI–EP nanocomposites was the best when the doping amount of KH550-Al2O3 was 8 wt%. The properties such as high heat-resistance, dielectric properties and ready attachment of impregnating varnish to steel plate with very high strength fully met the necessary requirement.

Two New 3-D Supramolecular Complexes Based on Tetradentate Carboxylate Linker and Bis-pyridyl-bis-amide Ligand: Syntheses, Structures and Electrochemical Properties

Two new 3-D supramolecular complexes [M2(4-bpcb)(bbtc)(H2O)5]·3H2O [M = Co (1), Ni (2), 4-bpcb = N,N′-bis(4-pyridinecarboxamide)-1,4-benzene, bbtc = 3,3′,4,4′-benzophenonetetracarboxylate] have been hydrothermally synthesized by self-assembly of 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride (bbtcd) and bis-pyridyl-bis-amide 4-bpcb mixed ligands. X-ray diffraction analysis reveals that two-dimensional (2-D) coordination networks of complexes 1 and 2 are constructed from neutral {M4(bbtc)2(H2O)10}n [M = Co (1), Ni (2)] ribbon-like chains and ligand 4-bpcb with bidentate coordination mode. The adjacent layers for 1 and 2 are further linked by hydrogen bonding interactions to form 3-D supramolecular frameworks. Moreover, the thermal properties and the electrochemical properties of the two title complexes have been reported. Two new three-dimensional supramolecular complexes based on two-dimensional polymer layer, [M2(4-bpcb)(bbtc)(H2O)5]·3H2O [M = Co (1), Ni (2)], have been synthesized from hydrothermal reaction of metal(II) chloride with the mixed ligands 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride (bbtcd) and bis-pyridyl-bis-amide ligand N, N′-bis(4-pyridinecarboxamide)-1,4-benzene (4-bpcb).

Synthesis and characterization of some polyimide-epoxy composites

AbstractComposites from some novel polyimide and commercial epoxy were prepared aiming to improve the thermal behavior of epoxy resins. Two diamines namely 4-4'-diamino-4''-hydroxytriphenyl methane (DHTM) and 4-4'- diaminotriphenyl methane (DTM) were synthesized by reacting aniline and aldehydes according to a reported method. The synthesized diamines were blended with commercially available epoxy 1, 4-butanedioldiglycidylether (BDDE) to synthesize model epoxy amine networks which were compared with polyimideepoxy composites. The polyimides were synthesized by reaction of these diamines with aromatic anhydride namely 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride (BTDA). These synthesized polyimides were dispersed in epoxy diamine networks to prepare composites. All the monomers and composites were characterized by making use of various analytical techniques including FTIR, NMR, TGA, DSC and XRD. Presence of hydroxyl group in the diamine helped in better dispersion of polyimide leading to high Tg and high char yield at 600 °C.

Preparation and Properties of High Performance Polyimide Foam

High performance polyimide (PI) foam has been prepared by esterification method using benzophenone tetracarboxylic acid dianhydride (BTDA) and diamino diphenylmethane (MDA) as the main materials in the mixture of methanol and tetrahydrofuran (THF). The cellular structure, thermal properties and flame retardance properties of PI foam were characterized by hot stage optical microscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetic analysis (TGA) and limiting oxygen Index (LOI), respectively. The results showed that the cellular structure was more ideal when the particle diameter of polyester ammonium salt (PEAS) precursor powder was 100μm; the glass transition temperature (Tg) of PI foam was more than 300°C, 5% weight loss temperature was above 500°C, LOI was as high as 50% and sound absorption was over 0.5.

Synthesis and characterization of poly(acrylate amic acid) and its application as negative‐tone photosensitive polyimides

AbstractThe dianhydride monomer 3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride and two diamine monomers, 4,4′‐diamino‐3,3′‐biphenyldiol (HAB) and 2,4‐diaminophenol dihydrochloride (DAP), were used to synthesize a series of poly(hydroxyl amic acid). Further functionalization by grafting acrylate groups yields the corresponding poly(acrylate amic acid) that underwent a crosslinking reaction on exposure to UV‐light and was used as a negative‐tone photosensitive polyimide (PSPI). The analysis of chemical composition and molecular weight of these poly(amic acid)s determined by nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared spectroscopy, and gel permeation chromatography revealed that the molecular weight of the poly(hydroxyl amic acid) increased with the molar content of HAB in the feedstock, because HAB exhibited higher polymerization reactivity than DAP. Moreover, the degree of grafting acrylate groups onto poly(hydroxyl amic acid) was determined by 1H‐NMR spectroscopy. The photoresist was formulated by adding 2‐benzyl‐2‐N,N‐dimethylamino‐1‐(4‐morpholinophenyl) butanone (IRG369) and isopropylthioxanthone as a photoinitiator, tetra(ethylene glycol) diacrylate as a crosslinker, and tribromomethyl phenyl sulfone as a photosensitizer. The PSPI precursor exhibited a photosensitivity of 200 mJ/cm2 and a contrast of 1.78. A pattern with a resolution of 10 μm was observed in an optical micrograph after thermal imidization at 300°C. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Synthesis and characterization of some aromatic polyimides

AbstractThe diamine 2‐methyl‐1,3‐bis(4‐aminophenyloxy)benzene was prepared via a nucleophilic substitution reaction and was characterized with Fourier transform infrared, elemental analysis, and 1H‐ and 13C‐NMR spectroscopy. The prepared diamine was also characterized with single‐crystal analysis. The geometric parameters of C19H18N2O2 were in the usual ranges. The dihedral angles between the central phenyl ring and the two terminal aromatic rings were 88.9 and 91.6°. The crystal structure was stabilized by NH···N hydrogen bonds. The diamine was then polymerized with 3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride, 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, 3,4,9,10‐perylenetetracarboxylic acid dianhydride, and pyromellitic dianhydride by either a one‐step solution polymerization reaction or a two‐step procedure. These polymers had inherent viscosities ranging from 0.61 to 0.85 dL/gm. Some of the polymers were soluble in most common organic solvents even at room temperature, and some were soluble on heating. The degradation temperatures of the resultant polymers fell in the range of 260–500°C in nitrogen (with only 10% weight loss). The specific heat capacity at 200°C ranged from 1.0 to 2.21 J g−1 K−1. The temperatures at which the maximum degradation of the polymer occurred ranged from 510 to 610°C. The glass‐transition temperatures of the polyimides ranged from 182 to 191°C. The activation energy and enthalpy of the polyimides ranged from 44.44 to 73.91 kJ/mol and from 42.58 to 72.08 kJ/mol K, respectively. The moisture absorption was found in the range of 0.23–0.71%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Bisphenol containing novel polyimides/glass fiber composites

AbstractA new diamine was synthesized using bisphenol‐A and p‐amino benzoic acid. Polyimides I and II were prepared with the diamine and pyromellitic dianhydride/3,3′,4,4′ benzophenone tetracarboxylic acid dianhydride. Bismaleimide (BMI) was synthesized using the same diamine and maleic anhydride. The prepared diamine and polyimides were characterized using FTIR. Thermo gravimetric analysis was used to study the thermal properties of synthesized polyimides and BMI. Woven glass fabric/unidirectional glass fiber‐polyimide/BMI composites were made and their properties (fiber volume fraction, density, tensile, flexural, impact, and hardness) were studied and compared with a few representative carbon fiber polyimide, carbon fiber–epoxy, and glass fiber–epoxy composites. The prepared composites were subjected to thermal aging and moisture absorption and their effects on tensile and flexural properties were studied. POLYM. COMPOS., 28: 372–380, 2007. © 2007 Society of Plastics Engineers

Synthesis and characterization of poly (amide-imide-imide)s based on diacids with bulky m-chloro phenyl moiety and rigid pyridine moiety

A series of novel aromatic diamines containing kinked m-chloro phenyl moiety was synthesized by the reaction of m-chloro benzaldehyde with 2,6-dimethyl aniline. The tetraimide diacid was synthesized by using the prepared diamine with benzophenone tetracarboxylic acid dianhydride (BPTDA) and p-amino benzoic acid. The polymers were prepared by treating the tetraimide diacid with different aromatic diamines. The structures of the monomers and polymers were identified by 1H-NMR, FTIR,13C-NMR and elemental analysis. The polymers showed excellent thermal stability, solubility and mechanical properties. Their structure–property relationship was studied by comparing these m-chloro polymers with polymers containing rigid Pyridine moiety.

Polyimides 7: Synthesis, characterization, and properties of novel soluble semifluorinated poly(ether imide)s

AbstractThree novel diamine monomers (VI, VII, and VIII) were synthesized. These diamine monomers lead to a number of semifluorinated poly(ether imide)s when reacted with different commercially available dianhydrides like pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), 2,2‐bis (3,4‐dicarboxyphenyl) hexafluoropropene (6FDA), and oxydiphthalic dianhydride (ODA) by thermal imidization route. Elemental analyses, IR and NMR techniques were used to characterize the monomers and polymers. The resulting polymers exhibited weight average molar masses up to 1.78 × 105 g mol−1 in GPC with respect to polystyrene standard and have very good solubility in several organic solvents such as NMP, DMF, DMAC, DMSO, chloroform, and THF. Very good solubility of these polymers in CDCl3 enables their complete characterization by proton as well as 13C‐NMR techniques. The polymers showed very high thermal stability with decomposition temperature (5% weight loss) up to 511°C in air and high glass transition temperature up to 311°C depending upon the exact repeating unit structure. The polymer films showed high modulus (up to 2.9 GPa) as was evaluated by DMA. The polymers also showed very low water absorption (0.16%), low dielectric constant (2.35 at 1MHz) and very good optical transmission. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3025–3044, 2007

Synthesis and characterization of polyimides and co-polyimides having pendant benzoic acid moiety

A novel diamine monomer, 2,4-diamino-4′-carboxy diphenyl ether had been synthesized. Several polyimides were prepared by reacting this diamine with commercially available dianhydrides, such as benzophenone tetracarboxylic acid dianhydride (BTDA), 4,4′-bis{hexafluoroisopropylidene bis (phthalic anhydride)}(6-FDA), oxydiphthalic anhydride (ODPA) and 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride (BPDA). Furthermore, copolymers from the resulting diamine and oxydianiline (ODA) with 6 FDA were also synthesized. The inherent viscosities of the polymers were 0.42–0.67dlg−1. The polymers have good solubility in polar aprotic solvents, high thermal stability up to 410°C in nitrogen and high glass transition temperatures (Tg) ranging from 260–330°C. These polymers formed tough flexible films by solution casting.