Synthesis,characterization, and thermal properties of novel arylene sulfone ether polyimides and polyamides

A new aromatic sulfone ether diamine was synthesized by nucleophilic aromatic substitution reaction of 5‐amino‐1‐naphthol with bis(4‐chlorophenyl) sulfone in the presence of potassium carbonate in a polar aprotic solvent. Polycondensation reactions of the obtained diamine with pyromellitic dianhydride (PMDA), benzophenonetetracarboxylic dianhydride (BTDA), and hexafluoroisopropylidene diphthalic anhydride (6FDA) resulted in preparation of thermally stable poly(sulfone ether imide)s. Poly(sulfone ether amide)s also were prepared by reaction of the diamine with terephthaloyl chloride (TPC) and isophthaloyl chloride (IPC). The prepared monomer and polymers were characterized by conventional methods. Physical and mechanical properties of polymers, including thermal stability, thermal behavior, solution viscosity, solubility behavior, and modulus, also were studied. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1487–1492, 2000     

Synthesis and properties of novel optically active polyimides

A facile synthesis of an optically active di‐isocyanate containing alkylene groups and a preformed imide structure is described. Polycondensation reactions of the prepared di‐isocyanate with pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and hexafluoroisopropylidene diphthalic anhydride resulted in the preparation of optically active, thermally stable polyimides. The prepared monomer and polymers were characterized by conventional methods. Optical and physical properties of the polymers including thermal stability, thermal behavior, solution viscosity, and solubility behavior were studied. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 514–518, 2001     

Synthesis and properties of novel diisocyanate based optically active polyimides

A new optically active diisocyanate was prepared from the reaction of l-leucine and pyromellitic dianhydride (PMDA) and subsequent transformation of intermediate imide-containing diacid to diisocyanate via Weinstock modification of Curtius rearrangement. Solution polycondensation reaction of the prepared diisocyanate with PMDA, 3,3,4,4-benzophenonetetracarboxylic dianhydride, and hexafluoroisopropylidene 2,2-bis(phthalic anhydride) resulted in the preparation of novel optically active polyimides. The optimal conditions for polyimidations (reaction duration and temperature programming) were obtained via study of the model compound. The monomer, model compound and polymers were characterized by FTIR, ¹HNMR, mass spectroscopy and elemental analysis and their optical and physical properties were studied as well.     

Fire-resistant polyimides and copolyimides based on 1-[(dialkoxyphosphinyl)methyl]-2,4- and -2,6-diaminobenzenes

Various phosphorus-containing polyimides were prepared by the reaction of 1-[(dialkoxyphosphinyl)methyl]-2,4- and -2,6-diaminobenzenes (1) with a tetracarboxylic dianhydride like pyromellitic dianhydride (PMDA) and benzophenone tetracarboxylic dianhydride (BTDA). In addition, copolyimides that contained approximately 3% phosphorus were prepared by the reaction of 1 and m-phenylenediamine (MPD) with the aforementioned tetracarboxylic dianhydrides. Elemental analysis, inherent viscosity, infrared (IR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) studies were performed to characterize the polymers. Their thermal properties were compared with those of the corresponding common polyimides. It was shown that the molecular weight and thermal stability of the polymers were reduced as the concentration of the phosphorus moieties increased. The fire-resistance of the copolyimides was evaluated by determining their limiting oxygen index (LOI) value. Copolyimides that contained about 3% phosphorus showed an LOI value approximately 30% higher, than the value of the corresponding common polyimides. In addition, a model diamic acid and diimide was synthesized by the reaction of 1-[di(2-chloroethoxyphosphinyl)methyl]-2,4- and - 2,6-diaminobenzene (DCEPD) with phthalic anhydride and characterized by elemental analysis, IR, proton nuclear magnetic (¹H-NMR) spectroscopy, DSC, and TGA. The pyrolysis behavior of the model compounds was investigated by gas chromatography-mass spectrometry (GC-MS). A direct cleavage of the P? C bond and a possible rearrangement to diisocyanates occurred during their pyrolysis.     

Unsaturated poly(ester-imide)s from hydroxy-terminated polybutadiene, dianhydride and diisocyanate

Hydroxy terminated polybutadiene has been used for the first time in the synthesis of poly(ester-imide)s [P(E-I)s]. Anhydride terminated polyester prepolymers were prepared by the reaction of two different polyols--polytetramethyleneoxide glycol (PTMG) of molecular weight 1000 and hydroxy terminated polybutadiene (HTPB) of molecular weight 2500--and different dianhydrides--pyromellitic dianhydride (PMDA), benzophenonetetracarboxylic dianhydride (BTDA) and 4,4^′-(hexafluoroiso-propylidene)diphthalic anhydride (HFDA). The prepolymers were then reacted with different diisocyanates--80:20 mixture of 2,4- and 2,6-tolylene diisocyanate (TDI), 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI) and 4,4^′-methylene bis(phenylisocyanate) (MDI) resulting in P(E-I)s. The P(E-I)s were characterised by FT-IR, FT-NMR, GPC, TGA, DSC and for static and dynamic mechanical properties. The polymers based on PTMG showed two distinct melting points and behave as thermoplastic elastomers. The thermal stability and mechanical properties of P(E-I)s based on HTPB were substantially higher than those based on PTMG.     

Time‐dependent morphology development in segmented polyetherurea copolymers based on aromatic diisocyanates

Time‐dependent morphology development in segmented polyureas obtained by the stoichiometric reactions between amine terminated poly(tetramethylene oxide) (PTMO) and aromatic diisocyanates were investigated. Polyureas were prepared by reacting aminopropyl terminated PTMO oligomer (M_n = 1100 g/mol) and various aromatic diisocyanates, such as 1,4‐phenylene diisocyanate (PPDI), 1,3‐phenylene diisocyanate (MPDI), diphenylmethane diisocyanate (MDI), and tolylene diisocyanate (TDI). Time‐dependent FTIR studies were conducted on thin films cast onto KBr discs, which were annealed at 200 °C for 10 min in an air oven. After removing from the oven, samples were placed into the FTIR spectrometer at room temperature, where time‐dependent spectra were recorded until equilibrium was reached. Time‐dependent peak reorganization in 3500–3100 cm^?1 (N? H region), 1750–1450 cm^?1 (C?O region or amide I and amide II regions), and 1180–1020 cm^?1 (C? O? C) were monitored. Depending on the chemical structure and the symmetry of the diisocyanate, major differences were observed in the time needed to reach an equilibrium morphology in these homologous poly(ether urea) copolymers. Symmetric PPDI‐based polyurea reached equilibrium in about 1 h compared with its asymmetric MPDI‐based counterpart, which needed about 150 h. Microphase development of the MPDI urea was also characterized by AFM, which gave similar results. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 471–483, 2009     

Novel polyimides with p-nitrophenyl pendant groups. Synthesis and characterization

Polyimides derived from a new dianhydride with p-nitrophenyl pendant groups have been synthesized and their properties compared with those of a reference series, without side groups. The polymers were obtained by combination of the novel monomer with aromatic diamines, in a two-step procedure that involved the synthesis of poly(amic acid) or poly(amic silyl ester) intermediates and the cyclization of them to polyimides by thermal treatment. The introduction of the polar nitro groups caused significant increase of the T_gs. On the contrary, the thermal stability was reduced because of the breakdown of C_Ar—NO₂ linkages around 400^oC. A slight decrease in mechanical properties was observed, due to the bulkiness of the side groups, that also produced an important decrease in the strength of the β relaxation, as determined by dynamic mechanical analysis. The solubility of the current polyimides in organic solvents was as poor as that of the parent unsubstituted polymers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3377–3384, 1999     

Thermal stability of methacrylic acid copolymers of Eudragits L,S, and L30D and the acrylic acid polymer of carbopol

The thermal stability of the powder or film forms of Eudragits L, S, and L30D and carbopol polymers was qualitatively investigated by microscopic reflectance Fourier transform infrared spectroscopy equipped with differential scanning calorimetry (FT-IR/DSC microscopic system). DSC and thermogravimetric analysis (TGA) were also used to study the thermal behavior of the pulverized powders of the raw material and the films of these polymers. The results indicate that a 6-membered ring cyclic anhydride formation was respectively produced by a heating process in the molecular structures of Eudragits L, S, and L30D and carbopol polymers via inter- or intrapolymer condensation. The peak intensity of the carbonyl stretching absorption of cyclic anhydride-related IR peaks appeared sharply near 1801 and 1759 (1751) cm⁻¹, and a peak near 1006 (1018) cm⁻¹ related to the antisymmetric stretching mode of C O C also appeared suddenly beyond the marked reaction temperature. The initial reaction temperature of anhydride formation for the Eudragits L, S, and L30D and carbopol polymers was observed respectively from near 186, 180, 170, and 100°C, whereas the rapid and marked reaction temperature from about 206, 188, 170, and 183°C appeared accurately from the reflectance FT-IR spectra. The DSC thermograms and TGA curves also confirmed these results. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2061–2067, 1999     

Investigation of nitrogen‐rich energetic polymers based on alkylbridged bis‐(1‐methyl‐tetrazolylhydrazines)

Nitrogen‐rich energetic polymers were synthesized by the polyaddition reaction of 1,2‐bis(5‐monomethylhydrazinyl‐1H‐tetrazolyl)ethane ( 1a ), 1‐methyl‐1,2‐bis(5‐monomethylhydrazinyl‐1H‐tetrazolyl)ethane ( 1b ), and 1,4‐bis(5‐mono‐methylhydrazinyl‐1H‐tetrazolyl)butane ( 1c ) with hexamethylene diisocyanate. The experiments showed that neither a polymerization from solution or bulk was possible. Therefore, a new method for the polymerization of tetrazolyl hydrazines had to be developed. The formed polymers were characterized by vibrational spectroscopy (IR) and elemental analysis. The energetic properties were investigated by bomb calorimetric measurements along with calculations using the EXPLO5 software. The thermal stability was investigated by DSC measurements. The properties render the polymers into promising compounds regarding an application as energetic binder. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 122–127, 2010     

Synthesis and chirooptical properties of optically active poly(ester imide)s based on axially asymmetric 1,1′‐binaphthyls

A series of optically active poly(ester imide)s (PEsI's) has been synthesized by the polycondensation reactions of new axially asymmetric dianhydrides, that is, (R)‐2,2′‐bis(3,4‐dicarboxybenzoyloxy)‐1,1′‐binaphthyl dianhydride and (S)‐2,2′‐bis(3,4‐dicarboxybenzoyloxy)‐1,1′‐binaphthyl dianhydride, and various diamines with aromatic, semiaromatic, and aliphatic structures. The polymers have inherent viscosities of 0.45–0.70 dL/g, very good solubility in common organic solvents, glass‐transition temperatures of 124–290 °C, and good thermal stability. Wide‐angle X‐ray crystallography of these polymers shows no crystal diffraction. In comparison with model compounds, an enhanced optical rotatory power has been observed for the repeat unit of optically active PEsI's based on aromatic diamines, and it has been attributed to a collaborative asymmetric perturbation of chiral 1,1′‐binaphthyls along the rigid backbones. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4318–4326, 2004     

Photolysis of bisphenol‐based polyurethanes in solution

Photolysis of bisphenol‐based polyurethanes, using bisphenols A, S, and AF with methylene diphenyl diisocyanate (MDI), has been shown by the observed changes in fluorescence spectra, reduced viscosity, and UV absorbance. Analysis of the fluorescence spectra of model compounds and polymers showed that para‐photo‐Fries and cleavage‐type products were the major components formed during photolysis. The reduced viscosity and UV absorbance changes are consistent with a two‐step photodegradation process. The reduced viscosity changes indicate that oxygen inhibition on the cleavage process is more significant for bisphenol S‐based polyurethanes than for bisphenol A‐ and bisphenol AF‐based polyurethanes. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1331–1339, 1999     

New polyurethanes and polyesters for second‐order nonlinear optical applications

New polymers for second‐order nonlinear optical (NLO) applications were synthesized and characterized. They were distinguished by the presence of chromophore groups, with various molecular hyperpolarizability values, used as pendants on substantially rigid backbones. The polymers were prepared through the reaction of tolylene‐2,4‐diisocyanate, or a suitable alkyloxyphthaloyl dichloride, with the N,N‐diethanol‐4‐(phenyl) group azo‐linked to a nitrofluorenone, nitrostilbene, nitrooxadiazole, or nitrothiadiazole moiety. The polymers exhibited good thermal stability, high glass‐transition temperatures, and an absence of crystallinity. The second‐order NLO properties of thin, transparent poled films, prepared by spin coating and thermal corona poling, were investigated for some of the polymers. The second harmonic coefficients, ranging between 18 and 25 pm/V, depended more on the alignment of the chromophore groups along the direction of the poling field than on their molecular hyperpolarizability. The temporal stability of the NLO properties of the polymers was also investigated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3013–3022, 2004     

Copoly(peryleneimide)s containing 1,3,4‐oxadiazole rings: Synthesis and properties

New copolyimides containing perylenediimide, oxadiazole and hexafluoroisopropylidene moieties were prepared by one‐step polycondensation reaction in solution at high temperature of aromatic diamines containing preformed oxadiazole ring with a mixture of a dianhydride having a perylene ring and another dianhydride with hexafluoroisopropylidene unit. The thermal stability and glass transition temperatures of these copolyimides were measured and compared with those of related polyimides. The solid polymers were also studied by polarized light microscopy and X‐ray diffraction which revealed a semicrystalline state consisting of face‐to‐face arranged columns of perylenediimide units. The film‐forming ability and properties of the resulting thin films were investigated by using atom force microscopy and scanning electron microscopy which showed that the films were organized into self‐assembled rod‐like structures. The UV‐Vis and photoluminescence properties in solution and in solid state were also investigated. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4230–4242, 2010     

Benzobistriazolophenanthroline polymers

The polycondensation of aromatic dihydrazidines (bisamidrazones) with 1,4,5,8-naphthalenetetracarboxylic acid or 1,4,5,8-naphthalenetetracarboxylic dianhydride in polyphosphoric acid led to high yields of soluble benzobistriazolophenanthroline polymers. Inherent viscosities in methanesulfonic acid of 0.25–2.51 dl g were recorded. Prior to polymer synthesis, a series of model compounds were prepared by reactions analogous to the polycondensation reaction. The polymer structure was established by elemental analysis and spectral comparisons of the polymers with model compounds. The thermal properties of the polymers were studied by thermal gravimetric analysis, differential thermal analysis, differential scanning calorimetry, and softening under load. Onset of breakdown in an air atmosphere occurs in the 440–450°C range. No softening under load was observed up to 450°C.     

Preparation and properties of novel polyimides derived from 4‐aryl‐2,6 bis(4‐amino phenyl)pyridine

To prepare novel polyimides with enhanced thermal stability and high solubility in common organic solvents, diamine monomers, 4‐aryl‐2,6 bis‐(4‐amino phenyl)pyridine, were introduced. The diamines were reacted with three different conventional aromatic dianhydrides including pyromellitic dianhydride, benzophenone tetracarboxylic dianhydride, and hexafluoroisopropylidene‐2,2‐bis(phthalic‐dianhydride) (6FDA) in dimethylacetamide solvent to obtain the corresponding polyimides via the polyamic acid precursors and chemical imidization. The monomers and polymers were characterized by Fourier transform infrared spectroscopy, ¹H NMR, mass spectroscopy, and elemental analysis; and the best condition of polymerization and imidization were obtained via the study of model compound. The polyimides showed little or no weight loss by thermogravimetric analysis up to 500 °C, and those derived from 6FDA exhibited good solubility in various polar solvents. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3826–3831, 2001     

Preparation and properties of imide‐containing elastic polymers from elastic polyureas and pyromellitic dianhydride

A new approach to obtain imide‐containing elastic polymers (IEPs) via elastic and high‐molecular‐weight polyureas, which were prepared from α‐(4‐aminobenzoyl)‐ω‐[(4‐aminobenzoyl)oxy]‐poly(oxytetramethylene) and the conventional diisocyanates such as tolylene‐2,4‐diisocyanate(2,4‐TDI), tolylene‐2,6‐diisocyanate(2,6‐TDI), and 4,4′‐diphenylmethanediisocyanate (MDI), was investigated. IEP solutions were prepared in high yield by the reaction of the polyureas with pyromellitic dianhydride in N‐methyl‐2‐pyrrolidone (NMP) at 165°C for 3.7–5.2 h. IEPs were obtained by the thermal treatment at 200°C for 4 h in vacuo after NMP was evaporated from the resulting IEP solutions. We assumed a mechanism of the reaction via N‐acylurea from the identification of imide linkage and amid acid group in IEP solutions. NMR and FTIR analyses confirmed that IEPs were segmented polymers composed of imide hard segment and poly(tetramethylene oxide) (PTMO) soft segment. The dynamic mechanical and thermal analyses indicated that the IEPs prepared from 2,6‐TDI and MDI showed a glass‐transition temperature (T_g ) at about −60°C, corresponding to T_g of PTMO segment, and suggested that microphase‐separation between the imide segment and the PTMO segment occured in them. TGA studies indicated the 10% weight‐loss temperatures (T₁₀) under air for IEPs were in the temperature range of 343–374°C. IEPs prepared from 2,6‐TDI and MDI showed excellent tensile properties and good solvent resistance. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 715–723, 2000     

Synthesis and characterization of hyperbranched poly(urea‐urethane)s based on AA* and B2B* monomers

Hyperbranched aromatic and aliphatic poly(urea‐urethane)s were prepared by the one‐pot method using 2,4‐toluylene diisocyanate (TDI), isophorone diisocyanate, and 2(3‐isocyanatopropyl)cyclohexyl isocyanate as AA* monomers and diethanol amine and diisopropanol amine as B₂B* monomers. The characteristics of the resulting polymers were very sensitive to slight changes in the reaction conditions, such as temperature, concentration, and type of catalyst used, as can be seen from the results of gel permeation chromatography and differential scanning calorimetry. The structures were analyzed in detail using ¹H and ¹³C NMR spectroscopy. By using model compounds, the different isomeric structures of the TDI polymers were deduced, their percentages of their linear, terminal, and dendritic subunits were calculated, and their degree of branching (DB) was determined. DB values up to 70% were reached depending on the reaction conditions and stoichiometry of the monomers. The number of terminal groups decreased significantly when dibutylamine was used to stop the reaction instead of B₂B*, indicating the presence of a significant number of unreacted isocyanate groups in the hyperbranched product when the polyaddition reaction was stopped. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3062–3081, 2004     

Investigation on novel thermoplastic poly(urethane-thiourea-imide)s with enhanced chemical and heat resistance

A new generation of segmented thermoplastic poly(urethane-thiourea-imide)s (PUTIs) was synthesized via reaction of polyethylene glycol and thiourea-based prepolymer with dianhydride as chain extenders. NCO-terminated prepolymer was synthesized from a new diisocyanate, 3-(3-((4-isocyanatophenyl)carbamoyl)thioureido)phenyl-4-isocyanatophenylcarbamate (IPCT), as a hard segment and PEG forming soft segment. The starting materials and polymers were characterized by conventional methods and physical properties such as solubility, solution viscosity, molecular weight, thermal stability and thermal behavior were studied. PUTIs showed partially crystalline structures. Weight average molecular weights of PUTIs (GPC measurements) were in the range of 1,68,694-1,97,035. Moreover, thermogravimetric analysis indicated that poly(urethane-thiourea-imide)s were fairly stable above 500 °C having T₁₀ of 521-543 °C. Investigation of the results authenticated the approach of introducing thiourea (using IPCT) and imide structure in polyurethanes for the improvement of thermal stability. In comparison to typical polyurethanes, these polymers exhibited better heat resistance, chemical resistance as well as processability.     

Thermal stability of structurally related polymers containing carborane and phthalocyanine groups

These studies were undertaken to determine the thermal behavior of structurally related polymers having a carborane nucleus in the recurring unit. Three of these products also contained phthalocyanine rings in their molecules. Results of thermal analysis studies show generally that the relative heat stability of the polymers conforms closely with indications given by similar investigations of structurally related intermediate and model compounds. A polymer with dimethylsiloxane units exhibited more resistance to thermal decomposition than similar products having urethane groups in their molecules. The urethane polymers derived from tolylene diisocyanate were found to be somewhat less heat-stable than analogous materials synthesized from methylenebis-(p-phenyl isocyanate). The relative order of thermal resistance of these materials follows that of more conventional polyurethane elastomers.     

Synthesis and characterization of optically active aromatic polyimides derived from 2,2′-bis(2-trifluoro- 4-aminophenoxy)-1,1′-binaphthyl and aromatic tetracarboxylic dianhydrides

Optically active 2,2′-bis(2-trifluoro-4-aminophenoxy)-1,1′-binaphthyl and its corresponding racemate were prepared by a nucleophilic substitution reaction of 1,1′-bi-2-naphthol with 2-chloro-5-nitrotrifluorotoluene and subsequently by the reduction of the resulting dinitro compounds. A series of optically active and optically inactive aromatic polyimides also were prepared therefrom. These polymers readily were soluble in common organic solvents such as pyridine, N,N′-dimethylacetamide, and m-cresol and had glass-transition temperatures of 256 ∼ 278 °C. The specific rotations of the chiral polymers ranged from 167 ∼ 258°, and their chiroptical properties also were studied. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4536–4540, 1999