Preparation and properties of novel processable polyimides derived from N,N‐bis(isocyanatoalkyl)‐1,2,4,5‐benzenetetracarboxylic‐1,2:4,5‐diimides

Two diisocyanate monomers containing methylene groups and built‐in imide structure have been prepared from the parent diacids via the Curtius–Weinstock rearrangement. Polyimides have been synthesized by solution polymerization of these isocyanates with pyromellitic dianhydride (PMDA), 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA), and hexafluoroisopropylidene‐2,2‐bis(phthalic‐anhydride) (6FDA). All monomers and polymers were characterized by conventional methods, and the physical properties of the polymers, including solution viscosity, solubility, thermal stability and thermal behaviour, were studied. © 2000 Society of Chemical Industry     

Preparation and properties of novel thermally stable pyridine‐based poly(amide imide amide)s

The 2,6‐bis(4‐nitrobenzamido)pyridine was prepared via reaction of 2,6‐diaminopyridine with two moles of 4‐nitrobenzoyl chloride in the presence of propylene oxide. Catalytic reduction of nitro groups of 2,6‐bis(4‐nitrobenzamido)pyridine with hydrazine yielded 2,6‐bis(4‐aminobenzamido)pyridine. Reaction of this diamine with two moles of trimellitic anhydride afforded a diacid with preformed amide and imide structures. Poly(amide imide amide)s were prepared by direct polycondensation reactions of the diacid with different diamines in the presence of triphenyl phosphite. All the precursors and polymers were fully characterized using common spectroscopic methods and elemental analysis and physical properties of the polymers including solution viscosity, thermal stability, thermal behavior, and solubility were studied. According to the obtained results the polymers showed high thermal stability and enhanced solubility. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of fluorinated poly(imide–amide–sulfone)s

A series of new, fluorinated poly(imide–amide–sulfone)s has been synthesized by solution polycondensation of aromatic diamines containing sulfone groups with diacid chlorides incorporating both imide and hexafluoroisopropylidene units. These polymers are soluble in polar amidic solvents, and their solutions can be cast into colorless, thin, flexible films having good electrical insulating properties and high thermal stability. The dielectric constant value is 3.49–3.68. The decomposition temperature in air is 464–479°C, and the glass transition temperature is in the range 279–359°C. All these characteristics have been discussed and compared with those of related fluorinated poly(imide–amide)s which do not contain sulfone groups and with other imide polymers without hexafluoroisopropylidene units. © 1995 John Wiley & Sons, Inc.     

Preparation of novel pyridine‐based,thermally stable poly(ether imide)s

Two aromatic, pyridine‐based ether diamines were prepared by the nucleophilic aromatic substitution reaction of 4‐aminophenol and 5‐amino‐1‐naphthol with 2,6‐dichloropyridine in N‐methyl‐2‐pyrrolidone as a solvent. Polycondensation reactions of the obtained diamines with pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and hexafluoroisopropylidene diphthalic anhydride resulted in six pyridine‐based, thermally stable poly(ether imide)s. The prepared monomers and polymers were characterized by common spectroscopic methods. The physical and thermal properties of the polymers, including the thermal behavior, thermal stability, solubility, and solution viscosity, were studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 22–26, 2004     

Synthesis and characterization of new thermally stable poly(ester‐imide)s derived from 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl and various aromatic dihydroxy compounds

A series of new alternating aromatic poly(ester‐imide)s were prepared by the polycondensation of the preformed imide ring‐containing diacids, 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl (2a) and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl (2b) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A model compound (3) was also prepared by the reaction of 2b with phenol, its synthesis permitting an optimization of polymerization conditions. Poly(ester‐imides) were fully characterized by FTIR, UV‐vis and NMR spectroscopy. Both biphenylene‐ and binaphthylene‐based poly(ester‐imide)s exhibited excellent solubility in common organic solvents such as tetrahydrofuran, m‐cresol, pyridine and dichloromethane. However, binaphthylene‐based poly(ester‐imide)s were more soluble than those of biphenylene‐based polymers in highly polar organic solvents, including N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide and dimethyl sulfoxide. From differential scanning calorimetry thermograms, the polymers showed glass‐transition temperatures between 261 and 315 °C. Thermal behaviour of the polymers obtained was characterized by thermogravimetric analysis, and the 10 % weight loss temperatures of the poly(ester‐imide)s was in the range 449–491 °C in nitrogen. Furthermore, crystallinity of the polymers was estimated by means of wide‐angle X‐ray diffraction. The resultant poly(ester‐imide)s exhibited nearly an amorphous nature, except poly(ester‐imide)s derived from hydroquinone and 4,4′‐dihydroxybiphenyl. In general, polymers containing binaphthyl units showed higher thermal stability but lower crystallinity than polymers containing biphenyl units. Copyright © 2005 Society of Chemical Industry     

Synthesis and characterization of poly(amide–imide)s and their precursors as materials for membranes

Water soluble diamine amic acids (DAAs) were synthesized by reacting aliphatic diamines with pyromellitic dianhydride. Poly(amide–amic acid)s (PAAs) were prepared by interfacial polycondensation of DAAs in aqueous sodium hydroxide solution with isophthaloyl chloride in dichloromethane. Poly(amide–imide)s (PAIs) containing alternating (amide–amide)–(imide–imide) sequences were obtained by thermal cycloimidization of the PAA films at 175°C for 4 h in a forced air woven. The PAIs were readily soluble in polar aprotic solvents such as dimethylformamide, dimethylacetamide, dimethylsulfoxide, and N‐methyl‐2‐pyrrolidone. The inherent viscosities of the polymers are in the range of 0.97–1.7 dL/g. The polymers were characterized by IR, ¹H nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA). Thin film composite membranes containing PAA ultrathin barrier layer were prepared by in situ interfacial polycondensation of DAA in water with trimesoyl chloride or isophthaloyl chloride in hexane on the surface of a porous polysulfone membrane. The membranes were characterized for water permeability and for the separation of NaCl and Na₂SO₄. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1721–1727, 2000     

Preparation and properties of new thermally stable poly(ether imide amide)s

2,6‐Bis(4‐aminophenoxy)pyridine was prepared via reaction of 4‐aminophenol with 2,6‐dichloropyridine in the presence of potassium carbonate. Reaction of the diamine with two mol of trimellitic anhydride afforded a diacid with preformed imide structures. Poly(ether imide amide)s were prepared by polycondensation reactions of the diacid with different diamines in the presence of triphenyl phosphite. All the monomers and polymers were fully characterized and the physical properties of the polymers including solution viscosity, thermal stability, thermal behavior and solubility were studied. Thermal analysis data showed the polymers to have high thermal stability. Copyright © 2004 Society of Chemical Industry     

Synthesis and characterization of rubbery highly fluorinated siloxane–imide segmented copolymers

The synthesis and characterization of a series of poly(siloxane–imide) block (or segmented) copolymers obtained by copolymerization of amine‐terminated polydimethylsiloxane with fluorinated aromatic compounds containing anhydride and amine functionality are reported. New fluorinated block copolymers have been synthesized to obtain organophilic polyimides potentially interesting for molecular membrane separations. The new aspects of this work relative to the literature are (1) a comparison of solution and solid‐state approaches in the imidization step to generate the target poly(siloxane–imide) copolymers and (2) exploration of new compositions involving fluorinated aromatic polymers derived from added diamine compounds. It is shown that the copolymer properties can be tailored from glassy to rubbery materials by varying the amount and the type of oligosiloxane used; the transition between glassy and rubbery properties is characterized at a siloxane content of 60 wt%. As a main result, it is shown that the solid‐state approach for inducing the cyclo‐imidization step is the more efficient one for synthesizing polymers with good mechanical properties, when the amount of siloxane block is increased in the copolymer series. Physical and chemical methods (thermogravimetric analysis, Fourier transform infrared spectroscopy, viscosity measurements) were used to characterize the copolymer properties obtained according to the two different synthesis routes. The obtained siloxane–imide copolymers are well soluble in a large variety of moderately polar solvents and exhibit very good thermal stability up to 400 °C. Hence the prepared copolyimides would seem to be promising candidates as organophilic membranes as well as gas permeation membranes. © 2012 Society of Chemical Industry     

High Tg second‐ order nonlinear optical poly(urethane–imide)s prepared from disperse Red 19, pyromellitic dianhydride,and tolylene diisocyanate

A series of poly(urethane–imide)s with high glass transition temperatures were easily prepared from a commercial nonlinear optical (NLO) chromophore (Disperse Red 19), pyromellitic dianhydride (PMDA), and 2,4‐tolylene diisocyanate (TDI). The resulting polymers possessed good solubility and high glass transition temperatures (231–272°C) and thermal decomposition temperatures. They exhibited excellent film‐forming properties and good‐quality films were easily obtained by spin coating. These polymers also possessed a high coefficient of optical nonlinearity with good temporal stability of the dipole orientation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 944–949, 2002     

Direct synthesis of new soluble and thermally stable poly(urethane‐imide)s from an imide ring‐containing dicarboxylic acid using diphenylphosphoryl azide

The direct preparation of various aromatic poly(urethane‐imide)s from 4‐p‐biphenyl‐2,6‐bis(4‐trimellitimidophenyl)pyridine (1) using diphenylphosphoryl azide (DPPA) was investigated. The polymers were mainly obtained by the conversion of imide ring‐containing diacid 1 to corresponding di(carbonyl azide) 2 with DPPA and then to diisocyanate 3 through the Curtius rearrangement of compound 2 followed by polyaddition of 3 in different amounts with aromatic dihydroxy compounds. The molecular weights of the resulting poly(urethane‐imide)s were evaluated viscometrically. All of the resulted polymers were thoroughly characterized by spectroscopic methods and elemental analyses. The poly(urethane‐imide)s exhibited an excellent solubility in a variety of polar solvents. Crystallinity nature of the polymers was estimated by means of WXRD. The glass‐transition temperatures of the polymers determined by DSC method were in the range of 191–202°C. The 10% weight loss temperatures of the poly(urethane‐imide)s from their thermal gravimetric analysis curves were found to be in the range of 392–416°C in nitrogen. The films of the resulting polymers were also prepared by casting the solution. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 869–877, 2006     

Thermal and dynamic mechanical characterization of polyurethane–urea–imide coatings

A series of NCO terminated polyurethane (PU)–imide copolymers were synthesized by a systematic three‐step process and were chain extended with different diol/diamine chain extenders. In the first step, isocyanate terminated PU prepolymers were prepared by reacting soft segments such as polyester (PE) polyols and polyether polyols such as polypropylene glycol (PPG‐1000) with hard segments like 2,4‐tolylene‐diisocyanate (TDI) or isophorone‐diisocyanate (IPDI) with NCO/OH ratio 2:1. In the second step, thermally stable heterocyclic imide ring was incorporated using isocyanate terminated PU prepolymers by reacting with pyromellitic dianhydride (PMDA) in a excess‐NCO:anhydride ratio of 1:0.5. The surplus NCO content after imidization was both moisture cured or partially reacted with chain extender and moisture cured. The films were characterized by thermogravimetric (TG), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) instruments. The adhesion strength of these coatings on mild steel (MS), copper (Cu), and aluminum (Al) is dependent on the nature of the substrate. The TGA analysis show good thermal stability. The DMTA results show the microphase separation between the different hard and soft segments. Finally, a structure to property correlation was drawn based on the structure of the soft, hard, and chain extender and the observed properties are useful for understanding and design of intelligent coatings. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3158–3167, 2006     

Thermally stable and organosoluble cardo binaphthylene based poly(amide imide)s and poly(ester imide)s

A new imide‐containing dicarboxylic acid based on a twisted binaphthylene unit, 2,2′‐bis(N‐trimellitoyl)‐1,1′‐binaphthyl (1), was synthesized from 1,1′‐binaphthyl‐2,2′‐diamine and trimellitic anhydride in glacial acetic acid. The structure of compound 1 was fully characterized with spectroscopic methods and elemental analysis. Series of thermally stable and organosoluble poly(amide imide)s (4a–4d) and poly(ester imide)s (5a–5d) with similar backbones were prepared by the triphenyl phosphite and diphenylchlorophosphate activated direct polycondensation of diimide dicarboxylic acid 1 with various aromatic diamines and diols, respectively. With due attention to the structural similarity of the resulting poly(amide imide)s and poly(ester imide)s, most of the differences between these two block copolyimides could be easily attributed to the presence of alternate amide or ester linkages accompanied by imide groups in the polymer backbone. The ultraviolet maximum wavelength values of the yellowish polymers were determined from their ultraviolet spectra. The crystallinity of these copolyimides was estimated by means of wide‐angle X‐ray diffraction, and the resultant polymers exhibited a nearly amorphous nature, except for the polymers derived from benzidine and 4,4′‐binaphthol. The poly(amide imide)s exhibited excellent solubility in a variety of highly polar aprotic solvents, whereas the poly(ester imide)s showed good solubility in less polar solvents. According to differential scanning calorimetry analyses, polymers 4a–4d and 5a–5d had glass‐transition temperatures between 331 and 357°C and between 318 and 342°C, respectively. The thermal behaviors of the obtained polymers were characterized by thermogravimetric analysis, and the 10% weight loss temperatures of the poly(amide imide)s and poly(ester imide)s were between 579 and 604°C and between 566 and 577°C in nitrogen, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3203–3211, 2006     

New thermochromic liquid–crystalline polymer: Synthesis and phase behavior

A series of new thermochromic side‐chain liquid–crystalline polymers were prepared. The chemical structures of the resulting monomers and polymers were characterized by element analyses, FTIR, ¹H‐NMR, and ¹³C‐NMR. Their mesogenic properties were investigated by differential scanning calorimetry, thermogravimetric analyses, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the content of dye groups on phase behavior of the polymers was discussed. The polymers P₁–P₃ showed smectic phase, and P₄–P₇ revealed cholesteric phase. The polymers containing less than 30 mol % of the dye groups showed good solubility, reversible phase transition, wider mesophase temperature ranges, and higher thermal stability. Experimental results demonstrated that the clearing temperature and mesophase temperature ranges decreased with increasing the concentration of the dye groups. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 329–335, 2005     

Synthesis and structure–property relationships of novel thiazole‐containing poly(amide imide)s with high refractive indices and low birefringences

The primary objective of this study was to investigate the structure–property relationships in high‐performance polymers with high refractive indices and low birefringences. A series of novel poly(amide imide)s (PAIs) were synthesized from a thiazole‐containing diimide–diacid monomer and various aromatic diamines. The influence of the pendant phenyl substituents on the optical properties of these PAIs was studied by comparison with the analogous polymers containing methyl groups. The PAIs exhibited excellent solubility and good thermal stability. The optical transmittances of the PAI films at 450 nm were higher than 75%. The combination of the thiazole units, thioether linkages and pendant phenyl rings provided the PAIs with high average refractive indices of 1.7361–1.7536 and low birefringences of 0.0066–0.0097 at 632.8 nm. © 2014 Society of Chemical Industry     

Thermomechanical characterization of thermoplastic polyimide–polyurea to improve the chain interaction via internal hydrogen bonds

Recently, we have studied polyimides (PIs) synthesized by incorporating an aromatic diamine monomer with a methylene linker, 4,4′‐methylenebis(2,6‐dimethylaniline), to make a robust main chain along with aliphatic polyetherdiamine backbone linkers to reduce rigidity. In this report, we incorporate a urea linkage into these materials in order to observe the effect of additional hydrogen bonding. The polymers are designed to exhibit thermal properties in between those of conventional aromatic PIs and polymers with wholly aliphatic ether diamine links. Herein, we demonstrate that the addition of 1,6 hexamethylene diisocyanate and the increase of hydrogen bonds at the urea linkage can be used to improve the thermal and mechanical properties of the PI. Furthermore, the imide ring is an important component to maintain the thermal stability characteristics in polyimide–polyurea hybrids. The polymers were characterized by FTIR, thermomechanical and calorimetric analysis, microhardness, and tensile testing. POLYM. ENG. SCI., 59:1948–1959, 2019. © 2019 Society of Plastics Engineers     

Synthesis and characterization of new aromatic poly(amide–imide)s based on 4‐aryl‐2,6‐bis(4‐trimellitimidophenyl) pyridines

New diimide–dicarboxylic acids, ie 4‐phenyl‐2,6‐bis(4‐trimellitimidophenyl)pyridine and 4‐p‐biphenyl‐2,6‐bis‐(4‐trimellitimidophenyl)pyridine, were synthesized by the condensation reaction of 4‐phenyl‐2,6‐bis(4‐aminophenyl)pyridine and 4‐p‐biphenyl‐2,6‐bis(4‐aminophenyl)pyridine with trimellitic anhydride in glacial acetic acid or dimethylformamide. The monomers were fully characterized by FT‐IR and NMR spectroscopies, and elemental analyses. A series of novel poly(amide–imide)s with inherent viscosities of 0.68–0.87 dl g^?1 was prepared from the two diimide–diacids with various aromatic diamines by direct polycondensation. The poly(amide–imide)s were characterized by FT‐IR and NMR spectroscopies. The λ_max data for the resulting poly(amide–imide)s were in the range of 260–292 nm. These polymers exhibited good solubilities in polar aprotic solvents. The 10 % weight loss temperatures are above 485 °C under a nitrogen atmosphere. Copyright © 2004 Society of Chemical Industry     

Synthesis and characterization of poly (imide–benzimidazole) hybrid nanocomposites using nano‐cluster of octa‐amino functionalized polyhedral oligomeric silsesquioxane

Poly (imide–benzimidazole)/polyhedral oligomeric silsesquioxane (POSS), nanocomposites were prepared by the reaction of the heterocyclic diamine monomer 2,2‐(1,2‐phenylene)‐bis(5‐aminobenzimidazole), octa(aminophenyl)silsesquioxane(OAPS), and benzophenonetetra carboxylic dianhydride (BTDA). The structure of the prepared monomers was confirmed by FTIR and NMR (²⁹Si, ¹H, and ¹³C) spectral studies. The thermal stability behavior of the poly (imide–benzimidazole) and poly (imide–benzimidazole)–POSS nanocomposite films were studied by differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). Dynamic mechanical analysis shows that the glass transition temperatures of the polyhedral oligomeric silsesquioxane (POSS) containing poly (imide–benzimidazole) nanocomposites are higher than that of the corresponding neat poly (imide–benzimidazole) systems. Decrease in the dielectric constant was observed with an increase in the determined amount of amino‐functionalized POSS in the poly (imide–benzimidazole) matrix. Further, the morphological studies were carried out by X‐ray diffraction and transmission electron microscopy. POLYM. COMPOS., 34:825–833, 2013. © 2013 Society of Plastics Engineers     

Effect of imide–oxazolidinone modification on the thermal and mechanical properties of HTPB‐polyurethanes

Imide‐ and oxazolidinone‐incorporated polyurethanes, based on hydroxy‐terminated polybutadiene (HTPB), were synthesized and characterized. Reaction of the blocked isocyanate terminals of the HTPB prepolymer with diepoxy compounds, containing preformed imide groups, was the strategy followed. The diepoxy resins were derived through reaction of an aliphatic and an aromatic dicarboxylic acid with preformed imide groups with a diepoxy resin. The intermediates and the polyurethane–imide–oxazolidinone were characterized by chemical, spectral, and elemental analyses. Incorporation of these heterocyclic groups caused dramatic improvements in the thermal and mechanical properties and the thermomechanical profile of the system. The improvements in properties were proportional to the hard‐segment content of the modified polyurethanes. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1731–1738, 1999     

Study on synthesis and thermal properties of polyurethane–imide copolymers with multiple hard segments

Different multiple hard segment polyurethane–imide copolymers (MHPUI) were synthesized and characterized. FTIR spectroscopy confirmed the characteristic absorption of the MHPUI copolymer. The difference in the imide group FTIR absorption bands in different MH segment PUI copolymers was found in this study and was explained by the different MH segment types, hard segment contents, and hard segment rigidity with different interactions of the molecular chains. The hard segment interaction in MHPUI with an increase of the structure rigidity of the short hard segments is strengthening. The DSC analysis revealed that the glass‐transition temperature of the soft segment of PUI rose in value from ?42 to ?3.4°C with the introduction of MH and different MH segments. The DSC results suggest that the soft segment is more compatible with the hard segment rigidity increase. The TGA results showed the hard segment structure symmetry has a more important role in the MHPUI thermal stability. Every sample containing symmetrical structure short hard groups (4,4′‐diphenylmethane diisocyanate or 4,4′‐diaminodiphenylmethane) is more thermally stable than that with worse symmetry structure groups (2,4‐toluene diisocyanate or 3,3′‐dichloro‐4,4′‐diamino‐diphenylmethane). The three‐step mechanism of PUI thermal degradation was further verified by the TGA study. The thermally unstable group was confirmed as urethane or a urea–urethane segment. The TGA results showed that MHPUI copolymers with higher separation of the soft–hard phase have higher thermal stability. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2206–2215, 2002     

Preparation and properties of flame retardant poly(urethane‐imide)s containing phosphine oxide moiety

The preparation of new poly(urethane‐imide)s (PUIs) having acceptable thermal stability and higher flame resistance was aimed. Two new aromatic diisocyanate‐containing methyldiphenylphosphine oxide and triphenylphosphine oxide moieties were synthesized via Curtius rearrangement in situ and polymerized by various prepared diols. Four aliphatic hydroxy terminated aromatic based diols were synthesized by the reaction between ethylene carbonate and various diphenolic substances. Chemical structures of monomers and polymers were characterized by FTIR, ¹H NMR, ¹³C NMR, and ³¹P NMR spectroscopy. Thermal stabilities and decomposition behaviors of the PUIs were tested by DSC and TGA. Thermal measurements indicate that the polymers have high thermal stability and produce high char. Polymers exhibit quite high fire resistance, evaluated by fire test UL‐94. The films of the polymers were prepared by casting the solution. Inherent viscosities, solubilities, and water absorbtion behaviors of the polymers were reported in. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009