Synthesis and properties of novel flame‐retardant poly(amide‐imide)s containing phosphine oxide moieties in main chain by microwave irradiation

Eight new flame‐retardant poly(amide‐imide)s with high inherent viscosities containing phosphine oxide moieties in main chain were synthesized from the polycondensation reaction of N,N′‐(3,3′‐diphenylphenylphosphine oxide) bistrimellitimide diacid chloride 7, with eight ;aromatic diamine 8a–h by two different methods such as solution and microwave‐assisted polycondensation. Results showed that the microwave‐assisted polycondensation by using a domestic microwave oven proceeded rapidly, compared with solution polycondensation and were completed within about 10–12 min. The resulting poly(amide‐imide)s 9a–h showed high thermal stability and flame‐retardant properties. All of the obtained polymers were fully characterized by means of elemental analysis, viscosity measurements, solubility test, and FTIR spectroscopy. Thermal properties of the PAIs 9a–h were investigated by using thermal gravimetric analysis (TGA), derivative thermogravimetric analysis (DTG), and differential scanning calorimetry (DSC). Char yield measurements at 600°C demonstrated that incorporating phosphine oxide moieties in polymer backbone markedly improves their flame retardancy. All of the earlier polymers were soluble at room temperature in various organic solvents such as NMP, DMF, DMSO, DMAc, and concentrated sulfuric acid. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4263–4269, 2006     

Synthesis and Characterization of Polyphosphonates having Azomethine Linkages

Abstract

Two bishydroxy azomethine monomers were synthesized and reacted with dichloro-phenyl phosphine oxide by the interfacial polycondensation method using a phase transfer catalyst at 0°C. The polymers were characterized by IR, ¹H-NMR, ³¹P-NMR, elemental analyses and X-ray diffraction study. These polymers are soluble in chlorinated aliphatic hydrocarbon solvents, such as CH₂Cl₂, CHCl₃ as well as polar aprotic solvents such as DMF, DMAC, NMP, DMSO. Thermal and flammability studies were carried out by TGA, DTA and limiting oxygen index (LOI) measurements. The polymers are self-extinguishing and begin to lose weight at around 290°C in air.     

Synthesis and properties of polyesterimides containing a bicyclo-octene ring

New polyesterimides containing a bicyclo-octene ring were synthesized by the polycondensation reaction of N,N′-dicarboxymethyl(bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid diimide)dimethylester and N,N′-dicarboxyphenyl(bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic acid diimide)dimethylester with various aliphatic diols. These polymers thus obtained are soluble in m-cresol, dimethylformamide (DMF), dimethylacetamide (DMAc) and dimethylsulfoxide (DMSO) except those from ethylene glycol. The polymers showed thermal stability above 350°C.     

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%.     

Design of multiple flame‐retardant polymers

Two polyphosphonates having multiple flame‐retardant actions were synthesized by interfacial polycondensation of a bisphenol and dichlorophenylphosphine oxide using cetyl trimethyl ammonium chloride as a phase transfer catalyst (PTC) at 0°C. The polyphosphanates thus prepared were characterized by viscometry, elemental analysis, IR, ¹H‐NMR, ³¹P‐NMR, and X‐ray diffraction studies. These polymers are highly soluble in polar solvents such as DMF, DMAc, DMSO, etc., as well as in chlorinated hydrocarbon solvents such as CH₂Cl₂, CHCl₃, etc. The thermal study of polymers was carried out by TGA and DTA analyses. The flammability of the polymers was studied by the limiting oxygen index measurements. The polymers are self‐extinguishing, and begin to lose weight at around 252°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 785–792, 2001     

Preparation and properties of polyimide fibers

Polyimides were synthesized from 4,4′-diamino diphenyl methane and pyromellitic dianhydride using low-temperature solution polycondensation. Solutions of these polyamic acids in dimethyl-formamide (DMF) were spun into fibers by the wet spinning technique using a mixture of DMF and water as coagulants. Various spinning parameters such as dope concentration, bath composition, and jet stretch were standardized to get polyimide fibers with optimum properties. It was observed that fibers spun at higher jet stretch did not cyclize satisfactorily. Higher dope concentrations gave fibers with better properties. Cyclodehydrated fibers were hot-drawn at 300°C. Fibers with a tenacity of 380 mN/tex, an extension at break of 10%, and initial modulus of 4060 mN/tex were obtained. Mechanical properties of fibers at elevated temperatures, i.e., 100 and 200°C were also measured. Heat aging at 100, 200, and 300°C was carried out for 10 hr. This resulted in an increase in the initial modulus of fibers. However, a 28% decrease in tenacity was observed when the fibers were heat-aged at 300°C. The dynamic thermogravimetry in air showed that fibers were stable up to 400°C. The activation energy of decomposition, calculated from these thermograms in the temperature range 540–610°C was 101 kJ/mole.     

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     

Synthesis and characterization of soluble copolyimides containing chalcone and phosphine oxide moieties in the main chain

The functional diamines 3,3′‐diaminochalcone and bis(3‐aminophenyl)‐3,5‐bis(trifluoromethyl)phenyl phosphine oxide were successfully prepared by simple and convenient procedures with short reaction times, and the overall yields were 78 and 70%, respectively. Copolyimides prepared from 3,3′‐diaminochalcone, bis(3‐aminophenyl)‐3,5‐bis(trifluoromethyl)phenyl phosphine oxide, and 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride exhibited excellent solubility in several organic solvents, such as dimethyl sulfoxide, N,N‐dimethylformamide, N‐methyl pyrrolidone, tetrahydrofuran, and acetone. They also showed very good thermal stability even up to 450°C for 5% weight loss (by thermogravimetric analysis) in nitrogen and a high glass‐transition temperature up to 274°C (by differential scanning calorimetry) in nitrogen. The copolymers' adhesive and photoreactive properties were also investigated, and it was confirmed that the copolyimide containing chalcone and phosphine oxide moieties in the main chain had good adhesiveness and photoreactivity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis of aliphatic–aromatic polyimides by two-step polymerization of aliphatic dianhydride and aromatic diamine

Aliphatic-aromatic polyimides were synthesized by polycondensation reaction in solvent. The effects of variables such as the kind of solvent, reaction time and temperature, and monomer concentration were investigated in detail on the reaction of 1,2,3,4-butanetetra-carboxylic dianhydride and 4,4′-diaminodiphenylmethane. The viscos-ities of polyimides were between 0.22 and 0.46 dL/g. The polyimides were soluble in some aprotic polar solvents, such as N,N′-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), dimethylsulfoxide (DMSO), and N,N′-dimethylformamide (DMF). They began to decompose at 380–410°C in air, and 10% weight loss temperatures were 430–450°C. © 1996 John Wiley & Sons, Inc.     

Isocyanate reactions in and with N,N-dimethylformamide

Solutions of phenylisocyanate (I) in DMF were stored at different temperatures in the presence of both polyurethane catalysts and 1,3-diphenylurea (II) . The reaction products were determined by HPLC. Beside the hydrolysis of I to II , a significant reaction of I with II to 1,3,5-triphenylbiuret (III) was observed at 20°C. Above 60°C, I reacted with the solvent to form N,N-dimethyl-N′-phenylformamidine (V) . In DMF, III dissociated to I and II already at temperatures >40°C.     

Spontaneous cyclodehydration of N-(o-aminophenyl) amic acids

The model reaction between phthalic anhydride and 1,2-diaminobenzene was studied under conditions analogous to those of the low-temperature polycondensation of aromatic dianhydrides with bis(o-diamines) in amide solvents followed by thermal cyclodehydration in condensed state to form ladder polyimidazopyrrolones (polypyrrones). The intermediate N-(o-aminophenyl)phthalamic acid was found to undergo spontaneous cyclodehydration to give N-(o-aminophenyl)phthalimide and 2-(o-carboxy-phenyl)benzimidazole. The reaction occurred at ambient temperature in the presence of water or alcohol without using a dehydration agent. The yield of imide-amine and/or carboxy-benzimidazole depended on the temperature of the condensation reaction. Temperatures below 0°C appeared to favor the formation of the carboxy-benzimidazole. Thermal cyclization of N-(o-aminophenyl)phthalamic acid passed through the same intermediates: imide-amine and carboxy-benzimidazole. The former converted to corresponding pyrrone above 200°C, while the secondary cyclization of the latter started above 250°C. Spontaneous cyclodehydration was also observed for polyamide acid-amine precursors obtained by low-temperature polycondensation of pyromellitic dianhydride with 3,3′-diaminobenzidine. The prepolymer solutions in DMF diluted with water at room temperature turned to a gel after 48–72 h. A spectroscopic study of the resulting polymers indicated the presence of significant amounts of imide cycles. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 609–619, 1998     

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.     

Synthesis and characterization of phosphorus-containing methacrylate-based difunctional crosslinkers and their use in UV-curable resin systems

Two new phosphorus-containing methacrylate-based difunctional crosslinking agents [bis(4-(2-methacryloyloxy)ethyl carboxyl)phenyl phosphine oxide (BEPPPO) and bis(4-(2-methacryloyloxy)ethylcarbonylaminophenyl)phenyl phosphine oxide (BUPPPO)], which can be good candidates for UV-curable coating applications, were synthesized by reacting either a phosphorus-containing diisocyanate [bis(4-isocyanatophenyl)phenyl phosphine oxide] or a phosphorus-containing diacid chloride [bis(4-chloroformylphenyl)phenyl phosphine oxide] with hydroxyethyl methacrylate. The structures of the monomers thus obtained were characterized by FTIR, mass, and ¹H-NMR spectroscopies. The contents of the new crosslinking agents in the UV-cured polymeric films were varied between 10 and 30% by weight. Mechanical, physical, and thermal characterizations of the UV-cured films were investigated. An increase in crosslinking agent content caused an increse in mechanical properties. Films containing BUPPPO had higher tensile strength values compared to the films containing BEPPPO. Thermogravimetric analysis of phosphorus-containing crosslinking agents revealed that incorporating phosphorus into the structure resulted in a high char yield up to 24.5% at 600°C. Water absorption values of UV-cured films were also affected by the amount and type of crosslinking agent. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2575–2585, 1999     

Synthesis and characterization of new flame‐retardant poly(amide‐imide)s containing phosphine oxide and hydantoin moieties in the main chain

Six new flame‐retardant poly(amide‐imide)s (PAIs) 9a–f with high inherent viscosities containing phosphine oxide and hydantoin moieties in main chain were synthesized from the polycondensation reaction of N,N′‐(3,3′‐diphenylphenylphosphine oxide) bistrimellitimide diacid chloride 7 with six hydantoin derivatives 8a–f by two different methods such as solution and microwave assisted polycondensation. Results showed that the microwave assisted polycondensation, by using a domestic microwave oven, proceeded rapidly, compared with solution polycondensation, and was completed in about 7–9 min. All of the obtained polymers were fully characterized by means of elemental analysis, viscosity measurements, solubility test, and FTIR spectroscopy. Thermal properties and flame retardant behavior of the PAIs 9a–f were investigated using thermal gravimetric analysis (TGA and DTG) and limited Oxygen index (LOI). Data obtained by thermal analysis (TGA and DTG) revealed that these polymers showed good thermal stability. Furthermore, high char yields in TGA and good LOI values indicated that these polymers are capable of exhibiting good flame retardant properties. These polymers can be potentially utilized in flame retardant thermoplastic materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5062–5071, 2006     

Kinetik der Polyphenylensulfid-Synthese

The kinetics of the polycondensation of Na₂S · 3H₂O and 1,4-dichlorobenzene to poly(phenylene sulfide) in 1-methyl-2-pyrrolidone as solvent was studied in a differential scanning calorimeter at temperatures from 220°C to 260°C. Stainless steel high-pressure capsules of 30 μl volume were used as micro reactors. The reaction is highly exothermic. At 220°C the enthalpy of reaction reaches a value of 180 kJ/mol. The polycondensation is characterized by an autocatalytic behaviour. The kinetics can be modelled by a second order equation with respect to the stoichiometrically charged monomers and a propagation rate constant being dependent on conversion. The activation energy of the polycondensation is 95 kJ/mol.     

Phosphine oxide containing aromatic polyester

A phosphine oxide containing aromatic polyester has been synthesized by the direct polycondensation reaction of bis[4-(m-carboxyphenoxy)phenyl]phenylphosphine oxide (m-BCPPO) and 4,4′-isopropylidene-diphenol (bisphenol A). The presence of phosphine oxide linkages in the backbone gives this polymer superior properties: namely thermo-oxidative stability, high char yield and solubility in common organic solvents.     

Anionic synthesis of poly(urethane-g-acrylonitrile)

High molecular weight poly(ester-urethane) based on diphenyl methane-4,4′-diisocyanate (MDI), PU1, and also on toluene diisocyanate (TD1), PU2, have been metallated using sodium hydride in N,N-dimethylformamide, (DMF). Metallation was confirmed by coupling samples of metallated PU1 and PU2 with methyl iodide and the use of infra-red, and n.m.r. G.p.c. studies indicated that an increase in the percentage of metallation at about 0°C in DMF caused a decrease in the stability of the soluble metallated backbone polymer and was accompanied by degradation. An increase in temperature from 0° to 100°C of a 15% metallated polyurethane sample in DMF increased the extent of degradation. At 0°C, polymers with a degree of metallation of less than 50% were relatively stable. At about 0°C in DMF, acrylonitrile was successfully grafted by anionic polymerization following metallation of PU1 and the graft copolymers were readily separated by fractionation from small amounts of the homopolymer, polyacrylonitrile. The graft copolymers were characterized by micro-analysis, solubility measurements, infra-red spectroscopy and viscometry. The vinyl monomers styrene, methyl methacrylate and vinyl acetate, and the cyclic monomers ethylene oxide, propylene oxide, N-methyl-2-pyrrolidone and hexamethylcyclotrisiloxane, could not be grafted anionically to the metallated polyurethane based on MDI.     

Synthesis and properties of polyamideimides containing a bicycloöctene ring

A series of aliphatic and aromatic polyamideimides containing a bicycloöctene ring were synthesized. Low-temperature solution condensation polymerization involving various diamines and N,N′-dichloroformylmethyl-[bicyclo-(2.2.2)-oct-7-ene-2,3,5,6-tetracarb-oxylic acid 2,3,5,6-diimide] (2) were employed. Most of these polymers thus obtained were soluble in m-cresol, DMF, DMAc and DMSO etc. The inherent viscosities of the polymers ranged from 0.07 to 0.40 dl/g (in DMF at 25°C). The polymers obtained from 2 and aromatic diamines showed thermal stabilities above 380°C. The aliphatic polymers were more unstable than the aromatic polymers.     

One-step synthesis of aromatic polyimides based on 4,4′-diaminotriphenylmethane

The feasibility of using a one-step high-temperature polycondensation for the synthesis of aromatic polyimides, based on 4,4′-diaminotriphenylmethane (DA-TPM), was studied. It was found that the reaction of DA-TPM with various aromatic dianhydrides in nitrobenzene at 180–200°C resulted in the formation of the high molecular weight soluble polyimides, PI-TPM. The reaction solutions cooled to ambient temperature were used for casting films. These PI-TPM films significantly exceeded their prototypes obtained by the thermal imidization of poly(amic acids) in terms of solubility and tensile properties. All studied polyimides demonstrated well-distinguished glass transition at 260–320°C. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of novel organosoluble polyesters based on a DIOL with azaquinoxaline ring

A series of new polyesters were synthesized by polycondensation of aliphatic and aromatic dicarboxylic dichlorides with a novel quinoxaline diol, 2,3‐bis (4‐hydroxy phenyl)‐5‐azaquinoxaline (DIOL). The DIOL was synthesized by reacting 4,4′‐dihydroxy benzil with 2, 3‐diaminopyridine (yield: 85%), and characterized by FTIR and ¹H‐NMR spectra. All polyesters showed good solubility in most aprotic polar solvents such as NMP (N‐methylpyrrolidone), DMF (dimethylformamide), DMSO (dimethylsulfoxide), DMAc (dimethylacetamide), HMPA (hexamethylenephosphoramide), and Py (pyridine). The inherent viscosity of polyesters was obtained in the range of 1.1–1.22 dL/mg. The glass transition temperatures of the polyesters were in the range of 200–280°C, as determined by DSC. The initial decomposition temperatures of the polyesters were above 300°C and the char yield at 750°C ranged from 30 to 60% under nitrogen atmosphere. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009