Methyl nadimide resins: Synthesis and characterization

This article describes the synthesis and characterization of several methyl nadimides endcapped resins based on tris(3-aminophenyl)phosphine oxide. These resins were prepared by reacting methyl-5-norbornene 2,3-dicarboxylic anhydride (methyl nadic anhydride) (MNA), pyromellitic dianhydride (PMDA)/3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA)/2,2-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6F), and tris(3-aminophenyl)phosphine oxide (TAP) in glacial acetic acid/acetone. Structural characterization of the resins was done by elemental analysis, IR, and ¹H-NMR. Thermal characterization of uncured resins using DSC and TGA techniques revealed an exothermic transition accompanied by a weight loss in the temperature range of 200–350°C. Residual weight at 800°C in nitrogen was found to be 47–55%. Isothermal curing of the resins was done at 340°C for 1 h in an air atmosphere. The cured resins were stable up to 400 ± 20°C. © 1994 John Wiley & Sons, Inc.     

Effect of structure on the thermal behaviour of ethynyl-terminated imide resins

A series of ethynyl-terminated aromatic imide monomers containing phosphine oxide in the backbone were synthesized by the reaction of tris(3-aminophenyl) phosphine oxide (TAP) or bis(3-aminophenyl)methyl phosphine oxide (BAP) with pyromellitic dianhydride (PMDA) or 3, 3′,4, 4′-benzophenone tetracarboxylic acid dianhydride (BTDA) or 4, 4′-perfluoroisopropylidenebis(phthalic anhydride), and 3-ethynyl aniline. Structural characterization was done by infrared, nuclear magnetic resonance spectroscopy and elemental analysis. Thermal characterization was done by differential scanning calorimetry and thermogravimetric analysis. The decomposition temperatures of cured resins were above 500°C in nitrogen atmosphere. Char yield at 800°C ranged from 52–63.5%.     

Tris(3-aminophenyl)Phosphine oxide-based nadimide resins. II

A series of phosphorus-containing nadimide end-capped resins having different backbones was prepared by reacting endo-5-norbornene-2-3-dicarboxylic acid anhydride (nadic anhydride), pyromellitic dianhydride (PMDA)/3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA)/2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6F) and tris(3-aminophenyl)phosphine oxide (TAP) in glacial acetic acid/acetone. Structural characterization of the resins was done by elemental analysis, FTIR, and ¹H-NMR. Thermogravimetric studies revealed a multistep decomposition reaction for uncured resins. Residual weight at 800°C in nitrogen was found to be 50–60%. Resins cured at 300°C for 1 h in air atmosphere were stable up to 440 ± 20°C and decomposed in a single step above this temperature. The char yields of cured resins were in the range 63–71.5%. © 1992 John Wiley & Sons, Inc.     

Synthesis and characterization of polyimides from novel 1-(3′,5′-bis(trifluoromethyl)benzene) pyromelliticdianhydride (6FPPMDA)

Mono-substituted dianhydride monomer, 1-(3′,5′-bis(trifluoromethyl)phenyl) pyromellitic dianhydride (6FPPMDA), was prepared via the Suzuki cross coupling reaction followed by oxidation and cyclodehydration. The monomer was characterized by FT-IR, NMR, elemental analyzer (EA) and melting point apparatus. For comparison, 1-(4′-trifluoromethylphenyl)pyromellitic dianhydride (3FPPMDA) and 1-phenyl pyromellitic dianhydride (PPMDA) were also utilized. The dianhydrides were used to prepare polyimides with aromatic diamines such as bis(3-aminophenyl) 3,4-bis(trifluoromethyl)phenyl phosphine oxide (mDA6FPPO), bis(3-aminophenyl) 4-(trifluoromethyl)phenyl phosphine oxide (mDA3FPPO), bis(3-aminophenyl) phenyl phosphine oxide (mDAPPO) and 1,1-bis(4-aminophenyl)-1-phenyl-2,2,2-trifluoroethane (p3FDAm). The polyimides were synthesized via a two-step process; preparation of poly(amic-acid) in p-chlorophenol with isoquinoline, followed by solution imidization at the reflux temperature for 12 h. Polymer characterization was carried out by FT-IR, NMR, GPC, DSC and TGA, and their solubility, solution viscosity, water absorption, CTE, dielectric constant and refractive index were also evaluated.     

Addition polyimides. I

Crosslinking of 4,4′(bismaleimido)diphenyl ether (BM) was investigated in presence of bis(m-aminophenyl)methylphosphine oxide (BAP), tris(m-aminophenyl)phosphine oxide (TAP), diaminodiphenyl ether (E) and 3,3-bis(p-aminophenyl)phthalide (AP). These crosslinked resins were examined for thermal stability by thermogravimetric analysis. A slight decrease in initial decomposition temperature, the temperature of maximum rate of weight loss, was observed, though the char yield in nitrogen atmosphere at 800°C did not change appreciably. Glass-cloth-reinforced laminates were fabricated from BM and amine mixtures. An improvement in mechanical properties was observed in the presence of phosphorus-containing di- and triamines.     

Phosphorus-containing epoxy for flame retardant. III: Using phosphorylated diamines as curing agents

Two phosphorus-containing diamine compounds, bis(4-aminophenoxy)-phenyl phosphine oxide and bis(3-aminophenyl)phenyl phosphine oxide, were synthesized for use as curing agents of epoxy resins. Phosphorylated epoxy resins were obtained by curing Epon 828 and Eponex 1510 with these two diamine agents. For raising the phosphorus contents of the resulting epoxy resins, the phosphorus-containing epoxy, bis(glycidyloxy)phenyl phosphine oxide (BGPPO), was also used. These two diamine agents showed similar reactivity toward epoxies. Their reactivities were higher than DDS and lower than DDM. High char yields in TGA evaluation were found for all the phosphorylated epoxy resins, implying their high flame retardancy. The excellent flame-retardant properties of these phosphorylated epoxy resins were also demonstrated by the high limiting oxygen index (LOI) values of 33 to 51. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 895–901, 1997     

Syntheses,structure, reactivity,and thermal properties of epoxy–imide resin cured by phosphorylated triamine

A new phosphorylated epoxy–imide polymer was obtained using diimide–diepoxide (DIDE) cured with tris(3-aminophenyl)phosphine oxide (TAPO). In addition, compositions of the synthesized diimide diepoxide (DIDE), Epon 828, and DEN 438 with common curing agents, e.g., 4,4′-diaminodiphenyl ether (DDE) and 4,4′-diaminodiphenylsulfone (DDS), were compared as to curing reactivity and heat and flame retardation with that of tris(3-aminophenyl)phosphine oxide. The reactivities of those curing agent toward the three kinds of epoxy resins, as measured by differential scanning calorimetry (DSC), were in the order DDE > TAPO > DDS. Through thermal gravimetric analysis (TGA), the thermal and flame resistances of epoxy were confirmed in this study as capable of being significantly improved through introduction of imide and phosphorus groups into the epoxide structure. © 1996 John Wiley & Sons, Inc.     

Adhesion property of novel polyimides containing fluorine and phosphine oxide moieties

Novel diamine monomers containing fluorine and phosphine oxide - bis(3-aminophenyl)-3,5-bis(trifluoromethyl)phenyl phosphine oxide (mDA6FPPO) and bis(3-aminophenyl)-4-(trifluoromethyl)phenyl phosphine oxide (mDAFPPO) - were utilized to prepare polyimides with dianhydrides such as 6FDA, BTDA or ODPA by the conventional two-step route, i.e. preparation of poly(amic acid) followed by solution imidization. The polyimides were characterized by FT-IR, NMR, DSC, and intrinsic viscosity measurements. The adhesion property of the polyimides was evaluated via a peel test with bare Cu foil, as well as silane/Cr-coated Cu foil, and failure surfaces were analyzed by SEM/EDX to elucidate the failure mechanism. The results were compared with those from the polyimides prepared from bis(3-aminophenyl)phenyl phosphine oxide (mDAPPO) containing only the phosphine oxide moiety, 1,1-bis(4-aminophenyl)-1-phenyl-2,2-trifluoroethane (3FDAm) containing only the fluorine moiety, and a commercial 3,3′-diaminodiphenylsulfone (mDDS). The polyimides with 3FDAm exhibited the highest T _g, followed by the mDAPPO-, mDA3FPPO-, and mDA6FPPO-based polyimides, but the mDAPPO-based polyimides exhibited the highest adhesion properties, followed by mDA3FPPO, mDA6FPPO, mDDS, and 3FDAm, which is attributed to the phosphine oxide and fluorine moieties.     

Addition polyimides. IV. Effect of structure on thermal characteristics

Chain extension reaction of bis(m-maleimido phenyl) methyl phosphine oxide (BP) with 4,4′-diaminodiphenylmethane (BP–M), 4,4′-diaminodiphenyl ether (BP–E), 3,3′- and 4,4′-diaminodiphenyl sulfone (BP–DDS_m and (BP-DDS_m respectively), tris (m-aminophenyl) phosphine oxide (BP–TAP), and 9,9-bis(p-aminophenyl) fluorene (BP–BAF) was carried out by refluxing 1:0.3 molar solution of BP:diamine. The melting temperature and exothermic peak associated with curing of BP decreased by such chain extension. The thermogravimetric analysis indicated more than 60% residual weight at 800°C in nitrogen atmosphere in BP–DDS_m, BP–DDS_p, and BP–TAP resins. These resins can be processed at low temperature and can be used for fabrication of composites with improved properties.     

Bis(3-aminophenyl)methyl phosphine oxide-based (methyl) nadicimide resins

Ten nadicimide/methyl nadicimide end-capped oligomeric resins were prepared by reacting endo-5-norbornene-2,3-dicarboxylic acid anhydride (methyl nadic anhydride), pyromellitic dianhydride (PMDA)/3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA)/2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6F), and bis(3-aminophenyl) methyl phospine oxide (BAP) in glacial acetic acid/acetone. Structural characterization of the resins was done by elemental analysis, IR, and ¹H-NMR. Multistep decomposition was observed in the TG scan of uncured resins in a nitrogen atmosphere. Residual weight at 800°C depended on the structure and ranged between 25 and 51%. Isothermal curing of the resins was done at 300°C for 1 h in an air atmosphere. These cured resins were stable to 350 ± 30°C and decomposed in a single step above this temperature. The char yield of the resins increased on curing and was in the range 34–70%. © 1997 John Wiley & Sons, Inc. J Appl Polm Sci 65:861–869, 1997     

Synthesis and characterization of polyimides from 4‐(diphenyl phosphine oxide)phenyl pyrromellitic dianhydride

A novel rigid‐rod type dianhydride monomer with phosphine oxide moiety, 4‐(diphenyl phosphine oxide)phenyl pyrromellitic dianhydride (POPPMDA), was synthesized via the Suzuki coupling reaction of 4‐(diphenyl phosphine oxide)phenyl boronic acid (POBB) and 1‐bromo‐2,3,5,6‐tetramethyl benzene (B4MB), followed by oxidation and cyclodehydration. The monomer was characterized by FTIR, NMR, EA, and melting point analyzer and utilized to synthesize polyimides with diamines such as bis(3‐aminophenyl)phenyl phosphine oxide (mDAPPO) and p‐phenylene diamine (pPDA) by varying their ratio. The polyimides were prepared via a conventional two‐step synthesis: preparation of poly(amic‐acid), followed by solution imidization. The polyimides were characterized by FTIR, NMR, DSC, TGA, and TMA, and their solubility, intrinsic viscosity, and adhesive properties were also evaluated. The polyimides exhibited high T_g (342–362°C), good thermal stability (>500°C), excellent adhesive property (134–107 g/mm), and low CTE (28–17 ppm/°C). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Studies on polypyromellitimides containing phosphorus

The paper describes the synthesis of several polypyromellitimide samples containing phosphine oxide in the backbone and maleimido groups as pendant side chains. These polymers were obtained by solution polycondensation reaction in DMF in three steps. First step involved the reaction of equimolar amounts of maleic anhydride (MA) and tris(3-aminophenyl) phosphine oxide (TAP) in DMF at 60°C for 2 h. Low temperature polycondensation was carried out at 0–5°C by the addition of 4,4'-diaminodiphenyl ether (DADPE) and pyromellitic dianhydride. Cyclodehydration of poly(amide acid) thus obtained was done by chemical means. Various copolymers thus obtained were characterized by intrinsic viscosity measurements, elemental analysis, and IR spectroscopy. Thermal behavior and curing characteristics of copolyimides were evaluated by thermogravimetry and differential scanning calorimetric studies. An increase in the char yield at 800°C was observed on increasing phosphine oxide content of polyimides.     

Synthesis and characterization of melt-processable polyimides derived from diaminodiphenylsulfone and benzophenone tetracarboxylic dianhydride with excellent heat resistance and thermoplasticity

Polyimide has excellent heat resistance, dielectric properties, and mechanical properties, and has a wide range of applications in aerospace, electronic packaging, and insulating materials. However, traditional polyimide is difficult to melt and dissolve, and its processing is difficult, which has become an important reason limiting its practical application. Therefore, the development of high temperature-resistant thermoplastic polyimide has become a research hotspot. To prepare high temperature-resistant thermoplastic polyimide materials, a series of thermoplastic polyimides was successfully prepared using 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 3,3′-diaminodiphenylsulfone, 2,3′,3,4′-benzophenone tetracarboxylic dianhydride, 9,9-bis(4-aminophenyl)fluorene, and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane via a two-step method. The effects of non-coplanar structure and bulky groups on the solubility, processability, and thermal properties of polyimide were studied. The structure, heat resistance and thermoplasticity of polyimide were characterized via various methods. The results show that the glass transition temperature of the prepared thermoplastic polyimide is between 292 and 302°C, and has excellent thermal resistance. The processing viscosity of polyimides is as low as 9210 Pa.s, and it has a certain degree of processing properties. It may be designed to be used in high temperature-resistant hot melt adhesives for structural components, high temperature-resistant melt processing resins, or thermoplastic composite materials used in the field of aerospace in the future.     

Imide oligomers having internal acetylene units in the backbone

Imide oligomers having internal acetylene groups in the backbone were prepared utilizing bis(3-aminophenyl)acetylene as an internal acetylene source. 2,2′-Bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), pyromellitic dianhydride (PMDA), 3,3′,4,4′-benzophenontetracarboxylic dianhydride (BTDA), and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) were used as acid dianhydride monomers. Amine-terminated oligomers with average degree of polymerization (DP) of 3, 5, and I 1 were prepared by controlling the ratio of monomers, and were end-capped with phthalic anhydride. Anhydride-terminated oligomers were similarly prepared and were end-capped with aniline. Imidization was conducted by refluxing in toluene. The DSC of the oligoimides containing internal acetylene units showed exotherm due to the crosslinking reaction of acetylene units. Onset temperature of the exotherm was 300–370°C, depending on the chemical structure and DP of oligoimide. By the thermal cure at high temperatures, the amount of exotherm decreased and exotherm shifted to higher temperature. Melt-processing of the oligoimides was carried out using a hydraulic press at 400°C. Melt-processed films were dark brown, opaque, and somewhat brittle. The films became less brittle with the increase of the DP of the oligomers. The films showed excellent thermal properties; T_g's were above 375°C, and their films maintained their mechanical properties aboveT_g.     

Synthesis, characterization and polymerization of isobutylbis(glycidylpropylether) phosphine oxide

In an attempt to obtain flame-retardant epoxy resins, a new diglycidylphosphine oxide, isobutylbis(glycidylpropylether)phosphine oxide (IHPO-Gly) was synthesized by reaction of isobutylbis(hydroxypropyl)phosphine oxide with epichlorohydrin and NaOH under phase transfer catalyst conditions. The thermal behaviour of IHPO-Gly was investigated by DSC and TGA and, together with thermal homopolymerization, isomerization and decomposition were detected. The reactivity of this novel diglycidyl compound was studied using boron trifluoride monoethylamine (BF₃·MEA) or 4-dimethylaminopyridine (DMAP) as catalysts and 2,4-diaminotoluene (DAT), hexahydrophtalic acid anhydride (HPA) or dicyandiamide (DICY) as hardeners. The thermal and flame retardant properties of the final thermosets were studied and V-0 materials were obtained in all cases except when BF₃·MEA was used as catalyst.     

Synthesis and Properties of a Novel Flame-Retardant Epoxy Resin Containing Biphenylyl/Phenyl Phosphonic Moieties

A novel reactive diol, bis-biphenyloxy (4-hydroxy) phenyl phosphine oxide (BBPHPPO) which contains both biphenylyl and phenyl phosphonic groups was synthesized. Flame retardant advanced epoxy resin was obtained by chain extension of diglycidyl ether of bisphenol-A (DGEBA) with the phosphorus-containing diol (BBPHPPO). The thermal properties and flame retardancy of cured epoxy resin were studied. The resulting BBPHPPO containing epoxy system exhibited higher glass transition temperature than that of advanced epoxy resins prepared from bisphenol-A (BA) and tetrabromobisphenol-A (TBBA). The high char yield and the high LOI value were observed to prove the excellent flame retardancy of this phosphorus-containing epoxy resin.     

Synthesis and properties of aromatic ether phosphine oxide containing oligomeric phthalonitrile resins with improved oxidative stability

A series of multiple aromatic ether-linked phthalonitrile resins containing an aromatic ether phosphine oxide group in the backbone have been synthesized and characterized. The oligomeric phthalonitrile monomers were prepared from the reaction of an excess amount of either bisphenol A or resorcinol with bis(4-fluorophenyl)phenylphosphine oxide in the presence of K₂CO₃ in a N,N-dimethylformamide/toluene solvent mixture, followed by reacting with 4-nitrophthalonitrile in a two-step, one-pot reaction. Rheometric measurements and thermogravimetric analysis of the cured resins showed that the oligomeric phthalonitrile resins maintained good structural integrity upon heating to elevated temperatures and exhibited excellent thermal properties. When subjected to long-term oxidative exposures, the phosphorus-containing phthalonitriles showed superior performance and less oxidative damage compared to other aromatic-containing phthalonitrile resins. Scanning electron spectroscopy studies showed the formation of microcracks during the oxidative aging at elevated temperatures.     

Multifunctional epoxy resins

The curing behavior of epoxy resins prepared by reacting epichlorohydrin with 4,4′-diaminodiphenyl methane (DADPM)/4,4′-diaminodiphenyl ether (DADPE) or 4,4′-diaminodiphenyl sulfone (DDS) was investigated using DDS and tris-(m-aminophenyl)phosphine oxide (TAP) as curing agents. A broad exothermic transition with two maxima were observed in the temperature range of 100–315°C when TAP was used as the curing agent. The effect of varying DDS concentration on curing behavior of epoxy resin was also investigated. Peak exotherm temperature (T_exo) decreased with increasing concentration of DDS, whereas heat of curing (ΔH) increased with an increase in amine concentration up to an optimum value and then decreased. Thermal stability of the resins, cured isothermally at 200°C for 3 h, was investigated using thermogravimetric analysis in a nitrogen atmosphere. Glass fiber-reinforced multifunctional epoxy resin laminates were fabricated and the mechanical properties were evaluated. © 1993 John Wiley & Sons, Inc.     

High temperature laminating resins based on maleimido end-capped pyromellitimide

A novel class of bismaleimides, biscitraconimides, and bisdichloromaleimides chain-extended by pyromellitimide was prepared and characterized by infrared and proton nuclear magnetic resonance spectroscopy. These polymer precursors were prepared by reacting maleic/citraconic/dichloromaleic anhydride (1 mol) with an equimolar amount of a diamine and subsequently with pyromellitic dianhydride (0.5 mol). The tetraamic acid formed was cyclodehydrated by chemical or thermal means. The curing behavior of polymer precursors was investigated by differential thermal analysis. Bismaleimide was thermally polymerized at a relatively higher temperature than the corresponding biscitraconimide and at lower temperature than bisdichloromaleimide. The curing temperature of monomers fluctuated between 209 and 318°C. Dynamic thermogravimetric analysis of the cured aromatic resins showed that they were approximately stable up to 370°C both in nitrogen and air. Their char yield was 53–63% at 800°C under anaerobic conditions. The relative thermal stability of the cured resins, with respect the diamine utilized for imidization, was of the order p-phenylenediamine > 4-aminophenyl ether > 4,4′-diaminodiphenylmethane > 4,4′-diaminodiphenylsulfone > hexamethylenediamine. In addition, the thermal and thermooxidative stability of polymers was ascertained by isothermal gravimetric analysis.     

Adhesion property of novel polyimides with 1‐[3′,5′‐bis(trifluoromethyl)phenyl] pyromellitic dianhydride

Novel polyimides were synthesized from 1‐[3′,5′‐bis(trifluoromethyl)phenyl] pyromellitic dianhydride (6FPPMDA) by a conventional two‐step process: the preparation of poly(amic acid) followed by solution imidization via refluxing in p‐chlorophenol. The diamines used for polyimide synthesis included bis(3‐aminophenyl)‐3,5‐bis(trifluoromethyl)phenyl phosphine oxide, bis(3‐aminophenyl)‐4‐trifluoromethylphenyl phosphine oxide, and bis(3‐aminophenyl)phenyl phosphine oxide. The synthesized polyimides were designed to have a molecular weight of 20,000 g/mol by off‐stoichiometry and were characterized by Fourier transform infrared, NMR, differential scanning calorimetry, and thermogravimetric analysis. In addition, their intrinsic viscosity, solubility, water absorption, and coefficient of thermal expansion (CTE) were also measured. The adhesion properties of the polyimides were evaluated via a T‐peel test with bare and silane/Cr‐coated Cu foils, and the failure surfaces were investigated with scanning electron microscopy. The 6FPPMDA‐based polyimides exhibited high glass‐transition temperatures (280–299°C), good thermal stability (>530°C in air), low water absorption (1.46–2.16 wt %), and fairly low CTEs (32–40 ppm/°C), in addition to good adhesion properties (83–88 g/mm) with silane/Cr‐coated Cu foils. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1801–1809, 2005