Synthesis and characterization of polyimides from 9,10-diphenyl-1,2,3,4,5,6,7,8-octahydro-2,3,6,7-anthracenetetracarboxylic 2,3:6,7-dianhydride

Summary A new dianhydride containing pendent phenyl group and alicyclic unit was prepared by a bis-Diels-Alder reaction of 1,4-diphenyl-2,3,5,6-tetrakis(bromomethyl)benzene with maleic anhydride, and polymerized with various aromatic diamines in one step at high temperature in NMP. Polymers were soluble in NMP and their inherent viscosities were in the 0.29∼0.47 dL/g range. Polyimides properties were investigated and discussed in terms of the chain structure resulting from the incorporation of different diamines. Received: 22 February 2002/Revised version: 26 March 2002/ Accepted: 4 April 2002     

Synthesis and characterization of polyimides from 9,10-dialkyloxy-1,2,3,4,5,6,7,8-octahydro-2,3,6,7-anthracenetetracarboxylic-2,3:6,7-dianhydrides and 4,4'-oxydianiline

Summary New dianhydrides having alkyloxy side chains were synthesized and polymerized with 4,4'-oxydianiline in NMP. Chemically cyclized polyimides were obtained with inherent viscosities of 0.30∼0.84 dL/g range. All the polymers were highly soluble in polar solvent such as NMP at room temperature. TGA pyrograms showed two-step degradation and in DSC thermograms the polymers exhibited T_gs between 124°C and 259°C. Wide-angle X-ray diffractograms revealed very low crystallinity and layered structure, which was better developed in the polymers with longer side chains Received: 16 October 2000/Accepted: 10 November 2000     

长链聚酰亚胺的制备与表征

以长链二胺4,4' 二(4 氨基苯氧基)二苯砜(BAPS)为单体,采用两步法分别与二酐PMDA、ODPA、BPADA合成了3种链长的聚酰亚胺。实验利用GPC监测0 05mol/L聚酰胺酸(PAA)的数均聚合度(Xn)及相对分子质量分布随缩聚时间的变化关系,结果表明该反应为一逐步缩聚反应,缩聚速率随二酐电子亲和性(EA)的递增而增加;与预聚体聚酰胺酸相比,热处理环化得到聚酰亚胺其数均分子质量( Mn)和特性粘度[η]均有所下降,而分布指数(D)增大。此外还利用红外光谱(FTIR)、差分扫描量热法(DSC)、热重分析(TGA)等对聚酰亚胺进行了表征,结果表明聚酰亚胺(PI)的玻璃化温度(tg)和热分解温度(td)随着聚合单元长度的增加而降低。     

Synthesis and characterization of some aromatic polyimides

The 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     

BAMPM基高可溶高透光聚酰亚胺的制备及表征

将3,3',5,5'-四甲基-4,4'-二胺基苯基-4'-甲基甲苯(BAMPM)与均苯四甲酸二酐(PMDA)、联苯四甲酸二酐(BPDA)、联苯醚二酐(ODPA)、六氟二酐(6FDA)通过一步高温缩聚法制备了四种新型聚酰亚胺(PI)。所得聚酰亚胺在普通有机溶剂中具有优异的溶解性。聚酰亚胺的玻璃化转变温度(Tg)超过332℃,10%热失重温度为530～537℃。溶液浇铸法制备的聚酰亚胺薄膜具有高光学透明性,UV截止波长为312～366 nm,80%透过率波长为382～436 nm。该薄膜的拉伸强度为60.5～84.7 MPa,弹性模量为1.7～2.4 GPa,断裂伸长率为5.9%～10.2%。     

Synthesis and characterization of polyimides containing pyridine moiety

A series of new polyimides was prepared by reacting 2,6‐diaminopyridine with various aromatic dianhydrides in DMF in 1 : 1 mole ratio. All the resulting polyimides were readily soluble in organic solvents such as dimethylformamide, N,N‐dimethylacetamide, pyridine, m‐cresol, THF, etc. They also show good film‐forming ability. The polyimides exhibit good thermal stability and mechanical properties. The polymers have high T_g in the range of 252–296°C. The inherent viscosities of the polymers vary from 0.81 to 1.28 dL/g. A new class of bismaleimide and polyaspartimide as also synthesized. All the resulting polymer structures were characterized by FTIR and elemental analysis. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1846–1853, 2004     

Synthesis and characterization of polyimides from divalent metal salts of p-aminobenzoic acid

Some 50 metal-containing polyimides with the metallic elements (Mg, Ca, Sr, Ba, Pb, Co, Ni) in the main chain were prepared first by reacting pyromellitic dianhydride (PMDA) with the mixture of divalent metal salts of p-aminobenzoic acid [ABA(M)] and 4, 4'-diaminodiphenylmethane (MDA) to form polyamic acid salts, and then the desired polyimides were obtained in high yield by separating the polyamic acid salts from the solvent and heating them under the imidization conditions. The structures of the samples were characterized by ¹H-NMR and IR, and the thermal properties of polyimides were measured by TG-DTA. It was found that the thermooxidative stability of polyimides decreased as a small amount of a metal element was introduced, and the stability of polymer varied slightly or tends to constancy as the metal content increased to a certain degree. In addition, the inherent viscosity of the polyamic acid salt solutions also decreased markedly with the increase of the metal content. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of formal-group-containing diisocyanates and polyimides therefrom

Four new formal-group-containing diisocyanates, namely, bis(3-isocyanatophenoxy) methane, bis(4-isocyanatophenoxy)methane, bis[2-(3-isocyanatophenoxy)ethyl] formal, and bis[2-(4-isocyanatophenoxy)ethyl] formal, were synthesized by the Curtius rearrangement from the corresponding dicarboxylic acids. The diisocyanates were polycondensed with pyromellitic dianhydride (PMDA) and benzophenonetetracarboxylic dianhydride (BTDA) in dimethylacetamide (DMAc) to obtain formal-group-containing polyimides. These polyimides were characterized by viscosity measurements, IR spectroscopy, X-ray diffraction, and thermogravimetric analysis.     

Synthesis and characterization of fluorine and nitrile containing polyimides

A series of polyimides were synthesized from new diamine, Bis [4,4′‐amino‐5,5′ trifluoromethyl phenoxy‐(hexafluoro isopropylidine) phenoxy phenyl] benzonitrile [BATFB] and various aromatic tetracarboxylic anhydrides by thermal and chemical imidization routes. The BATFB was synthesized in two steps by nucleophilic displacement reaction of 2,6‐dichloro benzonitrile, 4,4′‐(hexafluoro isopropylidine) diphenol and 2‐amino‐5‐fluoro benzotrifluoride in the presence of anhydrous potassium carbonate in N,N′‐dimethyl acetamide (DMAc) and the structure was confirmed by FTIR spectroscopy and CHNSO analyzer. The polymers were characterized by FTIR spectroscopy and thermal analysis were performed by differential scanning calorimetry and thermogravimetric analysis methods. The prepared polyimides had glass transition temperatures between 230 and 290°C and their 10% weight loss were recorded in the range 550–590°C in N₂ atmosphere. Majority of polymers are found to be soluble in most of the organic solvents such as DMSO, DMF, DMAc, m‐cresol, and THF even at room temperature and few becomes soluble on heating. The prepared polyimides showed water uptake values 0.34–0.54 wt % at room temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3455–3461, 2006     

Synthesis and properties of organosoluble polyimides based on 2,2′-diphenoxy-4,4′,5,5′-biphenyltetracarboxylic dianhydride

A novel method for the preparation of 2,2′-diphenoxy-4,4′,5,5′-biphenyltetracarboxylic dianhydride have been investigated. This new dianhydride contains flexible phenoxy side chain and a twist biphenyl moiety and it was synthesized by the nitration of an N-methyl protected 3,3′,4,4′-biphenyltetracarboxylic dianhydride and subsequent aromatic nucleophilic substitution with phenoxide. The overall yield was up to 75%. The dianhydride was polymerized with five different aromatic diamines to afford a series of aromatic polyimides. The polyimide properties such as inherent viscosity, solubility, UV transparency and thermaloxidative properties were investigated to illustrate the contribution of the introduction of phenoxy group at 2- and 2′-position of BPDA dianhydride. The resulting polyimides possessed excellent solubility in the fact that the polyimide containing rigid diamines such as 1,4-phenylenediamine and 4,4′-oxydianiline were soluble in various solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide and chloroform. The glass-transition temperatures of the polymers were in the range of 255-283 °C. These polymers exhibited good thermal stability with the temperatures at 5% weight loss range from 470 to 528 °C in nitrogen and 451 to 521 °C in air, respectively. The polyimide films were found to be transparent, flexible, and tough. The films had a tensile strength, elongation at break, and Young's modulus in the ranges 105-168 MPa, 15-51%, 1.87-2.38 GPa, respectively.     

N-羟甲基-2,3-二丁硫基四硫富瓦烯并[6,7-c]吡咯的合成

从4,5-二丁硫基-1,3-二硫杂环戊二烯-2-酮和N-对苯磺酰基-2-硫代-1,3-二硫杂环戊二烯并[4,5-c]吡咯出发,经交叉偶联、去保护得2,3-二丁硫基四硫富瓦烯并[6,7-c]吡咯(4)。化合物4在碱存在下与甲醛水溶液(37%)反应生成N-羟甲基化的产物。用核磁共振氢谱研究了标题化合物在不同极性溶剂中的偶合行为。     

Synthesis and characterization of new water-soluble precursors of polyimides

We have successfully synthesized and characterized new water-soluble precursors of polyimides based on dianhydrides with diaminobenzene sodium sulfonate (DABSS) and diaminostilbene disodium sulfonate (DASBDSS). The precursors are soluble in water and methanol as well as in several aprotic solvents. The optimum inherent viscosities of the poly(amic acids), obtained by varying reaction temperatures, were measured using a conventional Ubbelohde viscometer. The average molar mass of the polymers expressed as the “poly(ethylene oxide)-PEO/poly(ethylene glycol)-PEG equivalent” molecular masses obtained by gel permeation chromatography (GPC) showed significant broad molecular mass distributions with their polydispersities ranging from 2.9 to 4.6. FT-IR spectra revealed complete imidization of the polyimides. Their thermal properties were studied by techniques such as differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). Polyimides derived from the dianhydrides and DASBDSS showed better thermal stability up to 40°C in nitrogen than in oxygen atmosphere. However, polyimides based on the dianhydrides and DABSS were slightly more stable in oxygen than in nitrogen atmosphere. In oxygen, all the synthesized polyimides exhibited weight losses of about 50% in the range of 450–510°C. The overall weight losses of these polyimides under nitrogen were less than 50% at 700°C. New network polymellitimides based on mellitic trianhydride (MTA) and DABSS, and co-polymellitimides based on MTA, DABSS, and ODA (oxydianiline) were also synthesized and characterized successfully. Their thermal stabilities were compared with the linear polyimides using TGA and DSC.     

Aromatic polyimides from m‐phenylene diamines containing pendant groups: Synthesis and characterization

Two diamine monomers, 4‐[4‐(1‐methyl‐1‐phenylethyl)phenoxy]‐1,3‐diamino benzene and 4‐{4‐[(4‐methylphenyl)sulfonyl]phenoxy}‐1,3‐diamino benzene, were synthesized, and both diamines were polycondensed with three commercial dianhydrides to obtain aromatic polyimides containing pendant groups. The polyimides were characterized by solubility tests, viscosity measurements, IR, ¹H‐NMR, and ¹³C‐NMR spectroscopy, X‐ray diffraction studies, and thermogravimetric analysis. The polyimides had inherent viscosities of 0.33–0.58 dL/g in m‐cresol at 30 ± 0.1°C. All the polyimides were amorphous and were soluble in solvents such as N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidone, N,N‐dimethylformamide, and m‐cresol. Thermogravimetric analysis of the polyimides indicated no weight loss below 410°C under a nitrogen atmosphere. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1377–1384, 2005     

Aromatic polyimides: Synthesis,characterization, and evaluation of electric strength

Aromatic polyimides have been synthesized via the formation of polyamic acids in solution. This solution was cast into films that were thermally imidized. The imidization process was monitored using FTIR. The degree of imidization was also determined with thermo-gravimetric analysis. The electric breakdown field strength was tested under ac and dc conditions. Ac electric breakdown field strength measured in transformer oil was shown to follow a power-law dependence on film thickness. This dependence was not affected by the molecular mass of the polymer but changed with the degree of imidization and the electron-accepting properties of the diamine. High ac breakdown field values of polymides were obtained in dibutyl phthalate medium due to the suppression of partial discharges that occurs under these conditions. Measurements on films with thicknesses up to 60 μ showed no thickness dependence. No significant influence of the chemical structure on the break-down field strength was observed under these conditions. Breakdown field measurements under dc conditions showed high values, which were in good agreement with the peak values of the ac measurements in dibutyl phthalate. This indicates similarities in the intrinsic ac and dc breakdown processes. © 1993 John Wiley & Sons, Inc.     

Synthesis and characterization of polyimides and polyamide-imides containing azomethine linkages

Polyimides and polyamide-imides containing azomethine linkages in the polymer backbone have been synthesized from 4,4′-bis(4-isocyanatobenzylidene)-diaminodiphenylether (ODAI), 4,4′-bis(4-isocyanatobenzylidene)-diaminodiphenyl-methane (MADI), 4,4′-bis(4-isocyanatobenzylidene)-diaminodiphenylsulphone (SDAI), pyromellitic dianhydride (PMDA), 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA), and trimellitic anhydride (TMA), by a one-step process. The diisocyanates ODAI, MDAI and SDAI were prepared from the corresponding diacids, namely, 4,4′-bis(4-carboxybenzylidene)-diaminodiphenylether (ODAA), 4,4′-bis(4-carboxybenzylidene)-diaminodiphenylmethane (MDAA) and 4,4′-bis-(4-carboxybenzylidene)-diaminodiphenylsulphone (SDAA) by a Weinstock-modified Curtius rearrangement method. All the polycondensation reactions were conducted in N-methyl-2-pyrrolidone (NMP) under identical conditions and the polymers obtained were characterized by IR spectroscopy, solution viscosity, elemental analysis, thermogravimetric analysis, differential scanning calorimetry and X-ray diffraction.     

polyimides containing s-triazine rings in the main chain: Synthesis and characterization

Eight s-triazine-containing polyimides were synthesized by solution polycondensation of diisocyanates having an s-triazine ring with pyromellitic dianhydride in dimethylacetamide. Polyimides derived from meta-oriented diisocyanates were amorphous and soluble in dipolar aprotic solvents while those based on para-oriented diisocyanates were semicrystalline and insoluble in organic solvents. However, all the polyimides were soluble in concentrated sulphuric acid. The polyimides showed similar patterns of decomposition with no weight loss below 300°C in air.     

Synthesis and characterization of addition-type polyimides functionalized with diamine chromophore

Summary The Bismaleimide-Diamine Chromophore (2) prepolymers were prepared in acetone. The structure of the prepolymer was characterized. The prepolymer exhibited excellent film-forming quality and good solubility in low boiling point solvent. Thermal and NLO properties of the cured polyimides were evaluated. The chromophore content strongly influenced the thermal properties and order parameter Φ. Received: 21 July 1998/Revised version: 25 August 1998/Accepted: 28 August 1998     

Synthesis and characterization of thioether-containing polyimides with high refractive indices

Colorless and transparent polymers with high refractive indices and high temperature resistance have aroused great interest in the industrial community. Here, a series of polyimides (PIs) were prepared from a newly synthesized thioether-containing dianhydride, 1,4-bis(3,4-dicarboxy-phenylenesulfanyl)-benzene dianhydride, and various diamines by a two-step polycondensation reaction. Some flexible and tough films were obtained by casting solutions of them in poly(amic acid) (PAA). The tensile strengths and elongations at break of these PI films were greater than 58 MPa and 10%, respectively. All of them were thermally stable up to 500 °C in both air and nitrogen. Their glass transition temperatures were in the range from 204.5 to 265.8 °C. PI films with a thickness of 10–20 μm showed good optical transparency in the visible light region. Their cutoff wavelengths were lower than 400 nm and their transmittance was higher than 80% at 460 nm. The thioether linkages in the PIs endowed them with high average refractive indices (n _AV) of 1.68–1.74 and low birefringence values (Δn) of 0.0085–0.0120.