Sorption and transport of carbon dioxide in a polyimide from 3,3′4,4′-biphenyltetracarboxylic dianhydride and 4,4′-diaminodiphenyl sulfone

CO₂ sorption and transport were investigated for the polyimide prepared from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-diaminodiphenyl sulfone (DDS). The morphology of films did not change on annealing above the glass transition temperature and remained amorphous unlike the polyimide prepared from BPDA and 4,4′-oxydianilline (ODA). This seems to be due to the strong hindrance to rotation of the sulfonyl linkage. Sorption and transport data were analyzed according to the dual-mode model. Solubility, diffusion, and permeability coefficients at 20 atm and 80°C for BPDA-DDS polyimide were substantially equal between as-cast and annealed films and were 1.7, 2.2, and 3.7 times greater, respectively, than for the as-cast films of the BPDA-ODA polyimide. The higher solubility was due to larger values of the Henry's law solubility constant k_D, Langmuir capacity constant C, and the Langmuir affinity constant b. The sorption and transport properties were compared with those for amorphous glassy aromatic polymers including other polyimides. The relation of k, C, b, and the diffusion coefficients in the Henry's law population and the Langmuir population (D_D and D_H) with other properties of the polymers were discussed. Values D_D and D_H for BPDA-DDS polyimide were much larger than expected from the estimated free-volume fraction.     

Miscibility and cure kinetics studies on blends of bisphenol-A polycarbonate and tetraglycidyl-4,4′-diaminodiphenylmethane epoxy cured with an amine

Differential scanning calorimetry (DSC) has been applied to characterize the glass transition behavior of the blends formed by bisphenol-A polycarbonate (PC) with a tetrafunctional epoxy (tetraglycidyl-4,4′-diaminodiphenyl methane, TGDDM) cured with 4,4′-diaminodiphenylsulphone (DDS). A rare miscibility in the complete composition range has been demonstrated in these blends. Additionally, the blend morphology was examined using scanning electron microscopy (SEM) and a homogeneous single-phase PC/epoxy network has been observed in the blends of all compositions. Moreover, polycarbonate incorporation has been found to exert a distinct effect on the cure behavior of the epoxy blends. The cure reaction rates for the epoxy-PC blends were significantly higher due to the presence of PC. In addition, the cure mechanism of the epoxy blends was no longer autocatalytic. An n-th order reaction mechanism with n = 1.2 to 1.5 has been observed for the blends of DDS-cured epoxy with PC of various compositions studied using DSC. The proposed n-th order kinetic model has been found to describe well the cure behavior of the epoxy/PC blends up to the vitrification point. © 1995 John Wiley & Sons, Inc.     

Properties of tetra-N-glycidyl-4,4′-diamino diphenyl methane (TGDDM) cured thick films

Thick films of tetra-N-glycidyl epoxy resin of p,p′-diaminodiphenyl methane (TGDDM) were prepared using p,p′-diaminodiphenyl methane (DDM), p,p′-diaminodiphenyl sulfone (DDS) and diethylene triamine (DETA) as curing agent with or without the epoxy fortifiers PGEHA and VCDRC (at 20 phr level). These thick films were used to evaluate various physical, mechanical, chemical resistant and dielectric properties.     

Synthesis and characterization of novel nano size electroactive poly 4,4′‐diaminodiphenyl sulphone

The modification of electrodeposited polyaniline film by subsequent electrodeposition of 4,4′‐diaminodiphenyl sulfone (DDS) leads to a new material having nanostructure. The coated polymer films were treated with various pH solutions. The film adherent characteristics and surface morphology were studied using SEM. The electrochemically synthesized polyDDS revealed good redox behavior. The DDS was also polymerized by the chemical oxidation method using potassium persulphate. The polymer was characterized by UV‐Vis and FTIR spectral studies. The formation of polymer through the N? H group was understood from the single N? H stretching vibrational frequency at 3459 cm^?1. The X‐ray diffraction studies revealed the formation of nano sized (28 nm) crystalline polymer. The conductivity of the polymer was determined to be 1.07 × 10^?4 S.cm^?1. The solubility of the chemically polymerized powder was ascertained, and polyDDS showed good solubility in DMF and DMSO. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1702–1707, 2005     

Synthesis of symmetrical 2,2′,4,4′-tetrasubstituted[4,4′-bioxazole]-5,5′(4H,4′H)-diones and their reactions with some nucleophiles

Several symmetrical 2,2′,4,4′-tetrasubstituted[4,4′-bioxazole]-5,5′(4H,4′H)-diones 1a-f were obtained by dehydrodimerization of 5(4H)-oxazolones 2a-f . The configurations of four were established; one by X-ray crystallography rac- 1c , and three rac- 1a , meso- 1a and rac- 1b by ¹H nmr spectroscopy of their derivatives. Upon being heated, the bioxazolones isomerized, presumably by breakage of the 4,4′-carbon? carbon bond to form free radicals followed by their recombination. The results of a crossover experiment were consistent with a radical nature for this isomerization reaction. Treatment of three of the bioxazolones rac- 1a , meso- 1a and rac- 1c with methanol and amine nucleophiles led to ester and amide derivatives 7–11 of α,α'-dehydrodimeric amino acids.     

Poly(Ether sulfone)s made from 4,4′-dihydroxystilbene and 4,4′-difluorodiphenylsulfone: Synthesis,crosslinking, and epoxidation with hydrogen peroxide

High molecular weight polymers from trans-4,4′-dihydroxystilbene, bisphenols, and 4,4′-difluorodiphenylsulfone were synthesized by a nucleophilic displacement reaction using DMAc as solvent in the presence of potassium carbonate. Characterization and crosslinking studies of these polymers were carried out by DSC, TGA, TMA, x-ray diffraction, and solution and solid NMR. It was found that all polymers can be crosslinked to some extent on heating to 350°C. We also studied the epoxidation of these polymers with hydrogen peroxide in the presence of methyltrioctylammonium tetrakis (diperoxotungsto) phosphate (3—) as the catalyst in a biphasic system. The epoxidized polymers are thermally cross-linkable. Very efficient crosslinking was obtained by heating the epoxidized polymers at 350°C under nitrogen. © 1995 John Wiley & Sons, Inc.     

Liquid crystalline epoxy resins by polyaddition of aliphatic diepoxides with 4,4′-dihydroxybiphenyl

Liquid crystalline epoxy resins were synthesized from 4,4′-dihydroxybiphenyl (DHB), which was used as a mesogenic component, and diglycidyl ethers of aliphatic glycols (ethylene glycol and 1,6-hexanediol) which were used as flexible spacers. The synthesis was carried out by the catalytic polyaddition in the melt. Triphenylphosphine was used as the catalyst. The course of the polyaddition was investigated at various molecular ratios of the reactants. It was found that both linear and branched structures were formed in the course of the synthesis. The rates of the formation of the structures were calculated. The epoxy oligomers were investigated by DSC, polarizing microscope, and x-ray and IR spectroscopy. The molecular weight distribution was determined by GPC. The dependence of liquid crystalline properties of the obtained epoxy resins on the molecular weight and on the chain length of the flexible spacer was investigated. The molecular weight of the epoxy oligomers and the length of flexible spacer influence the phase transition temperatures. © 1995 John Wiley & Sons, Inc.     

Studies on the curing kinetics of epoxy resins using mixture of nadic/or maleic anhydride and 4,4′-diaminodiphenyl sulfone

Curing kinetics of diglycidyl ether of bisphenol-A (DGEBA) in the presence of maleic anhydride (MA)/or nadic anhydride (NA) or mixture of MA/NA: 4,4′-diaminodiphenyl sulfone (DDS) in varying molar ratios were investigated using differential scanning calorimetry. Curing behaviour of DGEBA in the presence of varying amounts of DDS:MA/NA was evaluated by recording DSC scans at heating rates of 5, 10, 15 and 20°C min⁻¹. The peak exotherm temperature depends on the heating rate, structure of the anhydride as well as on the ratio of anhydride: DDS. Thermal stability of the isothermally cured resins was evaluated by thermogravimetry. The char yield was highest in case of resins cured using mixture of DDS:MA (0.75:0.25; sample EM-1) and DDS:NA (0.75:0.25, sample EN-1).     

Crystallographic report: a double chain coordination polymer: {[Zn(H2O)6][Zn(3,3′,4,4′‐benzophenonetetracarboxylate)H2O]·4H2O}n

The double‐chain coordination polymer, {[Zn(H₂O)₆][Zn(bbtc)H₂O]·4H₂O}_n (bbtc = 3,3′, 4,4′‐benzophenonetetracarboxylate), features two kinds of zinc center. One is octahedrally coordinated by six aqua ligands and the other is coordinated by four carboxylate oxygen atoms, derived from three bbtc ligands, and a water molecule, forming a geometry intermediate between square‐pyramidal and trigonal bipyramidal. Copyright © 2003 John Wiley & Sons, Ltd.     

Intramolecular photocycloadditions of 6,6′-dimethyl-4,4′-polymethylenedioxy-di-2-pyrones

Photosensitized reactions of 4,4′-polymethylene-di-2-pyrones 2b-e afforded [2+2]-cycloadducts 3-5 , site-selectively. The selectivity depended upon the methylene chain length. Namely, the three carbon chain gave a syn head-to-head adduct 3b at the 3,4-position of the 2-pyrone ring, the four to six carbon chains gave syn head-to-head adducts 4c-e at the 5,6-position and/or anti head-to-head adducts 5d,e at the 5,6-position, respectively. The intramolecular cycloaddition mechanism was also explained from results calculated by means of PM3-CI method.     

An unusual P312 framework for the Ni(4,4′‐bipyridine)(H2O)4 chain

catena‐Poly[[[tetra­aqua­nickel(II)]‐μ‐4,4′‐bipyridine‐κ²N:N′] thio­sulfate dihydrate], {[Ni(C₁₀H₈N₂)(H₂O)₄]S₂O₃·2H₂O}_n, (I), and catena‐poly[[[tetra­aqua­nickel(II)]‐μ‐4,4′‐bipyridine‐κ²N:N′] sulfate methanol solvate monohydrate], {[Ni(C₁₀H₈N₂)(H₂O)₄]SO₄·CH₄O·H₂O}_n, (II), are built up of {[Ni(4,4′‐bipy)(H₂O)₄]²⁺}_n chains (4,4′‐bipy is 4,4′‐bipyridine) inter­woven in an unusual P3₁ fashion. Voids are filled by the corresponding counter‐anions and solvate mol­ecules, defining a complex three‐dimensional network surrounding them. In both structures, the cationic chains evolve around a set of twofold axes passing through the Ni^II ions and bis­ecting the aromatic amines through their N (and their opposite C) atoms.     

Thermotropic liquid‐crystalline polyesters of 4,4′‐biphenol and phenyl‐substituted 4,4′‐biphenols with 4,4′‐oxybisbenzoic acid

A series of thermotropic polyesters, derived from 4,4′‐biphenol (BP), 3‐phenyl‐4,4′‐biphenol (MPBP), and 3,3′‐bis(phenyl)‐4,4′‐biphenol (DPBP), 4,4′‐oxybisbenzoic acid (4,4′‐OBBA), and other aromatic dicarboxylic acids as comonomers, were prepared by melt polycondensation and were characterized for their thermotropic liquid‐crystalline (LC) properties with a variety of experimental techniques. The homopolymer of BP with 4,4′‐OBBA and its copolymers with either 50 mol % terephthalic acid or 2,6‐naphthalenedicarboxylic acid had relatively high values of the crystal‐to‐nematic transition (448–460 °C), above which each of them formed a nematic LC phase. In contrast, the homopolymers of MPBP and DPBP had low fusion temperatures and low isotropization temperatures and formed nematic melts above the fusion temperatures. Each of these two polymers also exhibited two glass‐transition temperatures, which were associated with vitrified noncrystalline (amorphous) regions and vitrified LC domains, as obtained directly from melt polycondensation. As expected, they had higher glass‐transition temperatures (176–211 °C) than other LC polyesters and had excellent thermal stability (516–567 °C). The fluorescence properties of the homopolymer of DPBP with 4,4′‐OBBA, which was soluble in common organic solvents such as chloroform and tetrahydrofuran, were also included in this study. For example, it had an absorption spectrum (λ_max = 259 and 292 nm), an excitation spectrum (λ_ex = 258 and 292 nm with monitoring at 350 nm), and an emission spectrum (λ_em = 378 nm with excitation at 330 nm) in chloroform. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 141–155, 2002     

The 3D Supramolecular Compound {[Cu2(L‐val)2(4,4′‐bipy)(H2O)2](NO3)2}n (L‐val = L‐valine anion, 4,4′‐bipy = 4,4′‐bipyridine)

{[Cu₂(L‐val)₂(4,4′‐bipy)(H₂O)₂](NO₃)₂}_n was synthesized and its crystal structure was determined by X‐ray diffraction. In the presence of 4,4′‐bipyridine, deprotoned L‐valine chelates Cu^II ions into coordination layers which were linked into a framework by hydrogen‐bonded chains resulting from nitrate anions and water molecules.     

meso‐2,2′‐Di­phenyl‐3,3′,4,4′‐tetra­hydro‐2,2′‐bi­furan‐5,5′(2H,2′H)‐dione

The crystal structure of the title compound, C₂₀H₁₈O₄, contains a crystallographic inversion center. The C—C bond linking the two halves of the mol­ecule is slightly elongated at 1.577 (3) Å.     

Pulsed NMR study of molecular motion in the diglycidyl ether of bisphenol-A cured with 4,4′-methylenedianiline

The monomeric diglycidyl ether of bisphenol-A cured with methylenedianiline has been studied by pulsed NMR. Values of the proton relaxation times T₁, T_1p, and T₂ have been measured over the temperature range ?160 to 200°C. The system was studied after being fully postcured at 180°C and after being cured at 100°C and at 54°C. The relaxation times are interpreted in terms of molecular motion in the cured resins, i.e., methyl group reorientation, segmental motions, and general molecular motion. The results are compared with those obtained previously by us for the uncured resin. Correlation frequencies for the segmental motions are compared with those obtained from dielectric relaxation and mechanical loss studies. There are at least two principal segmental motions present in the cured system, and the nature of these motions is found to depend on the cure temperature. These effects are discussed in terms of crosslinking and annealing of the system.     

On the configuration of 4,4′,6,6′-tetraphenyl-2,2′-dithiopyrylene

The title compound showed in its UV-VIS absorption spectra large red shifts of bands from solution to crystal indicating a pronounced intermolecular interaction between the dithiopyrylene π-electron systems. Dipole moment measurement in benzene solution gave a dipole moment value of 1.90 D which offers a direct evidence for the molecule in cis-configuration.     

Syntheses and Structural Characterization of Two Nitrilotriacetate Cobalt Complexes: [{CoK2(NTA)(Hmta)(H2O)3}NO3]n and [{Co(4,4′‐bpy)2(H2O)4}{Co2(NTA)2(4,4′‐bpy)(H2O)2}]

Two nitrilotriacetate cobalt complexes {[CoK₂(NTA)(Hmta)(H₂O)₃]NO₃}_n ( 1 ) and [{Co(4,4′‐bpy)₂(H₂O)₄}{Co₂(NTA)₂(4,4′‐bpy)(H₂O)₂}] ( 2 ) (NTA = nitrilotriacetate anion, Hmta = hexamethylenetetramine and 4,4′‐bpy = 4,4′‐bipyridine) were prepared and characterized by IR, elemental analysis and single crystal X‐ray diffraction study. The influence of the neutral ancillary ligands on the formation of the complexes with different structures in the Co‐NTA system was discussed. The coordination of NTA and Hmta to Co²⁺ ions only resulted in the formation of mononuclear [Co(NTA)(Hmta)]^? ions which are further connected by K⁺ ions and water molecules to form a three‐dimensional network. The use of 4,4′‐bpy as ancillary ligand in 2 led to the formation of separate mononuclear [Co(4,4′‐bpy)₂(H₂O)₄]²⁺ and dinuclear [Co₂(NTA)₂(4,4′‐bpy)(H₂O)₂]^2? which are further connected by hydrogen bonds to form a supramolecular three‐dimensional network. In these cases it seems to suggest that the addition of neutral ancillary ligand into the Co‐NTA system leads to the formation of lower dimensional structures when the contribution of alkali ions to the structural dimensionality is neglected.     

Cyclic and multicyclic poly(ether sulfone)s by polycondensation of 5,5′,6,6′‐tetrahydroxy‐ 3,3,3′,3′‐tetramethyl spirobisindane and 4,4′‐difluorodiphenylsulfone

5.5′,6,6′‐Tetrahydroxy‐3,3,3′,3′‐tetramethyl spirobisindane (TTSBI) was polycondensed with 4,4′‐difluorodiphenylsulfone (DFDPS) in DMSO with K₂CO₃ as catalyst and azeotopic removal of water. The feed ratio of DFDPS/TTSBI was varied from 1.0/1.0 to 2.0/1.0 at concentrations avoiding gelation. At feed ratios around 1.0/1.0 hyperbranched polymers were a minority and cyclic poly(ether sulfone)s were the predominant reaction products. With increasing feed ratio of DFDPS more and more multicyclic polymers were formed, and at a feed ratio of 1.9/1.0 perfect multicycles free of functional groups were the vast majority of the reaction product. Despite variation of the reaction conditions quantitative conversion was not achieved. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5597–5605, 2007