ABTS•+ scavenging activity of polypyrrole,polyaniline and poly(3,4‐ethylenedioxythiophene)

Although many methods are available for the evaluation of the antioxidant capacity of samples presented in the liquid state, typically food and beverages, to date only the 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH) assay has been applied to the measurement of the antioxidant capacity of solid samples such as active packaging materials. A modified 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS) assay has been successfully developed for the measurement of the antioxidant capacity of conducting polymer powders. The ABTS^?+ radical scavenging activity of polypyrrole (PPy), polyaniline (PANI) and poly(3,4‐ethylenedioxythiophene) (PEDOT) powders was compared. The ranking order for greatest antioxidant capacity among the conducing polymer powders was PANI > PPy > PEDOT. The reduced forms of all the three conducting polymer samples were found to show greater radical scavenging activity than their as‐prepared partially oxidized forms. The modified ABTS assay is a simple, rapid and sensitive method for evaluating the antioxidant capacity of conducting polymer powders. The method is also suitable for composite antioxidant materials comprising a conducting polymer and a conventional packaging polymer. Copyright © 2010 Society of Chemical Industry     

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     

Palladium(II)‐Catalyzed Aerobic Intermolecular Cyclization of Acrylic Acid with Alkenes to α‐Methylene‐γ‐butyrolactones

The methodology in this article is a palladium(II)/copper(II)‐ or palladium(II)‐catalyzed intermolecular cyclization of acrylic acid with alkenes to produce α‐methylene‐γ‐butyrolactone derivatives using molecular oxygen as an environmentally benign oxidant. In this system, the carboxylato, especially trifluoroacetato, or trimethylacetato ligand, plays a quite important role to afford a high catalytic activity by suppressing the deposition of palladium(0) black.     

Synthesis and characterization of novel aromatic poly(amide‐imide)s derived from 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl or 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl and various aromatic diamines

New aromatic diimide‐dicarboxylic acids having kinked and cranked structures, 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl (2a) and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl (2b), were synthesized by the reaction of trimellitic anhydride with 2,2′‐bis(4‐aminophenoxy)biphenyl (1a) and 2,2′‐bis(4‐aminophenoxy)‐1,1′‐binaphthyl (1b), respectively. Compounds 2a and 2b were characterized by FT‐IR and NMR spectroscopy and elemental analyses. Then, a series of novel aromatic poly(amide‐imide)s were prepared by the phosphorylation polycondensation of the synthesized monomers with various aromatic diamines. Owing to structural similarity, and a comparison of the characterization data, a model compound was synthesized by the reaction of 2b with aniline. The resulting polymers with inherent viscosities of 0.58–0.97 dl g^?1 were obtained in high yield. The polymers were fully characterized by FT‐IR and NMR spectroscopy. The ultraviolet λ_max values of the poly(amide‐imide)s were also determined. The polymers were readily soluble in polar aprotic solvents. They exhibited excellent thermal stabilities and had 10% weight loss at temperatures above 500 °C under a nitrogen atmosphere. Copyright © 2003 Society of Chemical Industry     

Synthesis and characterization of poly(hydroxyether). I. Poly(hydroxyether) based on 2,2‐bis(4‐hydroxyphenyl)hexafluoropropane and 2,2‐bis(4‐hydroxyphenyl)propane

Linear poly(hydroxyethers) (PHEs) were prepared by the base‐induced condensation of bisphenols with epichlorohydrin in a polar mixed solvent. The bisphenols used were 2,2‐bis(4‐hydroxyphenyl)propane (bisphenol A) and 2,2‐bis(4‐hydroxyphenyl)‐hexafluoropropane (bisphenol AF). Bisphenol A–based homo‐PHE (HPHE‐A), bisphenol AF–based homo‐PHE (HPHE‐AF), and copoly(hydroxyethers) (CPHEs) based on both the bisphenols with various compositions were characterized in terms of chemical structure, thermal property, solubility, and contact angle. The incorporation of bisphenol AF unit into HPHE‐A brought about the increases in the glass‐transition temperature, the solubility in organic solvents, and the hydrophobicity. The sequence of the repeating unit in the copolymer was analyzed by ¹H–NMR and the result agreed well with the one calculated as a random copolymer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1687–1696, 2001     

Potential Energetic Plasticizers on the Basis of 2,2‐Dinitropropane‐1,3‐diol and 2,2‐Bis(azidomethyl)propane‐1,3‐diol

Different carboxylic acid derivatives of 2,2‐dinitropropane‐1,3‐diol (DNPD) and 2,2‐bis(azidomethyl)propane‐1,3‐diol (BAMP) were synthesized to investigate their suitability as energetic plasticizers. The syntheses were carried out using acyl chlorides of acetic, propionic, and butyric acid. The obtained products were characterized by elemental analysis, NMR, and IR spectroscopy. The energetic properties of the synthesized compounds were calculated on the basis of the computed heats of formation at the CBS‐4M level of theory using the EXPLO5 version 6.02 computer code. Investigations of physical stabilities were carried out using BAM drop hammer and friction tester. Low and high temperature behavior was determined by differential scanning calorimetry (DSC). The energetic and physical properties of the synthesized compounds were compared to the literature known energetic plasticizers N‐butyl nitratoethylnitramine (BuNENA) and diethylene glycol bis(azidoacetate) ester (DEGBAA). For analyzing the plasticizing abilities, mixtures of glycidyl azide polymer (GAP) and poly(3‐nitratomethyl‐3‐methyloxetan) (polyNIMMO) were prepared with both propionyl based compounds in different ratios and investigated regarding their glass transition temperatures and viscosity. Both compounds showed plasticizing effects in the range of BuNENA.     

Polyurethanes based on 2,2‐Dinitropropane‐1,3‐diol and 2,2‐bis(azidomethyl)propane‐1,3‐diol as potential energetic binders

On the base of 2,2‐bis(azidomethyl)propane‐1,3‐diol (BAMP) and 2,2‐dinitropropane‐1,3‐diol (DNPD) four different polyurethanes were synthesized in a polyaddition reaction using hexamethylene diisocyanate (HMDI) and diisocyanato ethane (DIE). The obtained prepolymers were mainly characterized using vibrational spectroscopy (IR) and elemental analysis. For determination of low and high temperature behavior, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used. Investigations concerning friction and impact sensitivities were carried out using a BAM drop hammer and friction tester. The energetic properties of the polymers were determined using bomb calorimetric measurements and calculated with the EXPLO5 V6.02 computer code. The obtained values were compared with the glycidyl azide polymer (GAP). The compounds turned out to be insensitive toward friction (>360 N) and less sensitive toward impact (40 J). The good physical stabilities, along with their sufficient thermal stability (170–210 °C) and moderate energetic properties renders these polymers into potential compounds for applications as binders in energetic formul;ations. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43991.     

Extended Lifetimes of Gold(III) Chloride Catalysts using Copper(II) Chloride and 2,2,6,6‐Tetramethylpiperidine 1‐Oxyl (TEMPO)

The turnovers of a gold(III) chloride catalyst were increased by 3,300% with the addition of several equivalents of 2,2,6,6‐tetramethylpiperidine 1‐oxyl (TEMPO) and catalytic amounts of copper(II) chloride. A three‐component coupling reaction between piperidine, phenylacetylene, and benzaldehyde yielded a propargylic amine in quantitative conversions and isolated yields when gold(III) chloride was added in catalytic amounts, but the gold catalyst decomposed and had little to no reactivity when a second set of piperidine, phenylacetylene, and benzaldehyde was added after the reaction was complete. Thus, only one cycle was possible with gold(III) chloride. The addition of TEMPO and copper(II) chloride to reactions with gold(III) chloride maintained the catalytic activity of gold for up to 33 cycles. This result demonstrates a new way to greatly increase the turnovers of a gold(III) chloride catalyst with the addition of inexpensive, commercially available reagents.     

Highly fluorinated poly(ether‐imide)s derived from 2,2′‐bis(3,4,5‐trifluorophenyl)‐4,4′‐diaminodiphenyl ether and aromatic dianhydrides

A new diamine, 2,2′‐bis(3,4,5‐trifluorophenyl)‐4,4′‐diaminodiphenyl ether (FPAPE) was synthesized through the Suzuki coupling reaction of 2,2′‐diiodo‐4,4′‐dinitrodiphenyl ether with 3,4,5‐trifluorophenylboronic acid to produce 2,2′‐bis(3,4,5‐trifluorophenyl)‐4,4′‐dinitrodiphenyl ether (FPNPE), followed by palladium‐catalyzed hydrazine reduction of FPNPE. FPAPE was then utilized to prepare a novel class of highly fluorinated all‐aromatic poly(ether‐imide)s. The chemical structure of the resulting polymers is well confirmed by infrared and nuclear magnetic resonance spectroscopic methods. Limiting viscosity numbers of the polymer solutions at 25 °C were measured through the extrapolation of the concentrations used to zero. M_n and M_w of these polymers were about 10 000 and 25 000 g mol^?1, respectively. The polymers showed a good film‐forming ability, and some characteristics of their thin films including color and flexibility were investigated qualitatively. An excellent solubility in polar organic solvents was observed. X‐ray diffraction measurements showed that the fluoro‐containing polymers have a nearly amorphous nature. The resulting polymers had T_g values higher than 340 °C and were thermally stable, with 10% weight loss temperatures being recorded above 550 °C. Based on the results obtained, FPAPE can be considered as a promising design to prepare the related high performance polymeric materials. Copyright © 2011 Society of Chemical Industry     

Synthesis and Characterization of 4,4′,5,5′‐Tetranitro‐2,2′‐Bi‐1H‐imidazole (TNBI)

We synthesized 4,4′,5,5′‐tetranitro‐2,2′‐bi‐1H‐imidazole (TNBI), which may serve as a new energetic filler for high explosive formulations. TNBI was synthesized by treating an excess amount of sodium nitrate with 2,2′‐bi‐1H‐imidazole (BI), which was produced from glyoxal and ammonia gas. The overall synthetic yield was 32%. The synthesized TNBI was characterized by performing various chemical analyses including NMR, IR, and CHN analyses. Small scale sensitivity tests were carried out at both research institutes (ADD and ARDEC). The sensitivity results varied from ‘more sensitive than RDX’ to ‘substantially less sensitive than RDX’ according to the purity and conditions of the test samples. Based on our careful characterizations, this large variation in sensitivity was attributed to the moisture content that was present in the test samples due to a hygroscopic nature of TNBI. We also found that the hygroscopic nature of TNBI changed significantly due to the amount of impurities, especially sulfates.     

High‐performance composite nanofiltration membranes fabricated via ternary mixture: Complementary preponderance of the fluorine‐containing monomer 2,2′‐bis(1‐hydroxyl‐1‐trifluoromethyl‐2,2,2‐triflutoethyl)‐4,4′‐methylene dianiline and the rigid monomer bisphenol F

In a previous study, we proved that tailoring the polyamide backbone stiffness is an effective way to fabricate high‐performance polyamide nanofiltration (NF) membranes. However, in the previous study, we mainly focused on the flat membrane and did not consider its chlorine tolerance. In this study, by regulating the aqueous‐phase compositions in the interfacial polymerization process, chlorine tolerance on NF hollow‐fiber membranes was endowed while the membrane performance stayed high. The experimental results show that when the ratio of Piperazine (PIP)–bisphenol F (BPF)/2,2′‐bis(1‐hydroxyl‐1‐trifluoromethyl‐2,2,2‐triflutoethyl)‐4,4′‐methylene dianiline (BHTTM) was 5:1:4, the NF membrane possessed a permeate flux of 21.0 L m^?2 h^?1 bar^?1 and an Na₂SO₄ rejection up to 90.0%. X‐ray photoelectron spectroscopy analysis also confirmed that the polymerization degree of the PIP–BPF–BHTTM NF membrane was the highest. Moreover, the NF membrane could tolerate active chlorine to over 10,000 ppm h Cl. After the active chlorine treatment, the permeate flux increased over 30.0 L m^?2 h^?1 bar^?1, and the Na₂SO₄ rejection was about 90.0%. Although the PIP–BHTTM NF membrane also possessed good chlorine tolerance, its permeate flux (after active chlorine treatment) was only 60% of that of the PIP–BPF–BHTTM NF membrane. Therefore, the PIP–BPF–BHTTM NF membrane possessed a combination of high flux and high chlorine tolerance and showed good potential in water treatment in rigorous environments. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46482.     

Random copolymerization of 2,2‐dimethyltri methylene carbonate and ε‐caprolactone using a rare‐earth tris(4‐tert‐butylphenolate)s as a single‐component initiator

Highly random copolymers of 2,2‐dimethyltrimethylene carbonate (DTC) and ε‐caprolactone (CL) were synthesized by single component rare‐earth tris(4‐tert‐butylphenolate)s [Ln(OTBP)₃] for the first time. The influences of reaction conditions on the copolymerization initiated by La(OTBP)₃ have been examined in detail. The monomer reactivity ratios of DTC and CL determined by the Fineman–Ross method are 4.0 for r_DTC and 0.27 for r_CL. The microstructure of the copolymer was determined by the analyses of the diads DTC–DTC, DTC–CL, CL–DTC and CL–CL of the ¹H NMR spectra. The high degree of randomness of the chain structure was further confirmed by the ¹³C NMR spectra and differential scanning calorimetry. The thermal properties of the copolymers as a function of composition are reported. The mechanism investigated by ¹H NMR data indicates that the rare‐earth tris(4‐tert‐butylphenolate)s initiate the ring‐opening copolymerization of DTC and CL with acyl‐oxygen bond cleavages of the monomers. Copyright © 2004 Society of Chemical Industry     

Ambipolar and multi‐electrochromic polyimides based on N,N‐di(4‐aminophenyl)‐N′,N′‐diphenyl‐4,4′‐oxydianiline

A series of novel aromatic polyimides were synthesized from N,N‐di(4‐aminophenyl)‐N′,N′‐diphenyl‐4,4′‐oxydianiline and aromatic tetracarboxylic dianhydrides through a conventional two‐step procedure. Most of the polyimides exhibited reasonable solubility in organic solvents and could afford robust films via solution casting. The polyimides exhibited high thermal stability, with glass transition temperatures in the range 227–273 °C and 10% weight‐loss temperatures in excess of 550 °C. All the polyimide films showed ambipolar redox and multi‐electrochromic behaviors. They exhibited two reversible oxidation redox couples at 0.94–0.98 and 1.09–1.12 V versus Ag/AgCl in acetonitrile solution. A coupling reaction between the radical cations of the pendent triphenylamine units occurred during the oxidative process forming a tetraphenylbenzidine structure which resulted in an additional redox state and color change. © 2014 Society of Chemical Industry     

Palladium on Carbon‐Catalyzed Synthesis of Benzil Derivatives from 1,2‐Diarylalkynes with DMSO and Molecular Oxygen as Dual Oxidants

A palladium on carbon (Pd/C)‐catalyzed synthetic method for the preparation of benzil derivatives from 1,2‐diarylalkynes has been established using dimethyl sulfoxide (DMSO) and molecular oxygen as dual oxidants. Regardless of the electrical nature of the functional groups on the aromatic rings, 1,2‐diarylalkynes were oxidized to the corresponding benzil derivatives in high to excellent yields. Furthermore, the oxidation could efficiently be catalyzed by both the dry and wet types of Pd/C under atmospheric conditions.     

Catalytic effect of the Cu(II)‐ and Fe(III)‐cyclo‐hexanebutyrates on olive oil oxidation measured by Rancimat

In this work the Rancimat technique (temperature 110 °C and air flow 20 l/h) was used in order to test the catalytic effect induced by Cu(II)‐and Fe(III)‐ions on olive oil oxidation. Different amounts of Cu(II)‐ and Fe(III)‐cyclohexanebutyrates were added to a refined olive oil. Copper was shown to be a more active catalyst than iron. In fact, the induction time of the oil was halved by the addition of about 120 ng/g of copper versus 9000 ng/g of iron. The effect of copper and iron was also evaluated on the oil enriched with increasing quantities of caffeic acid (50, 100 and 200 mg/kg). The addition of this phenol induced a significant protective effect which delayed the oxidation of both the control and the oil samples enriched with metals. However, copper‐catalyzed oxidation also in the presence of the antioxidant, thus decreasing the oil oxidative stability approximately three times compared to the control.     

Theoretical Studies on Molecular and Explosive Properties of 4,4′,5,5′‐Tetranitro‐2,2′‐bi‐1H‐imidazole (TNBI)

We performed theoretical studies to predict the molecular structure, molecular properties, and explosive performance of 4,4′,5,5′‐tetranitro‐2,2′‐bi‐1H‐imidazole (TNBI). High levels of ab initio and density functional theories were employed to predict the molecular structure of TNBI. Predicted TNBI structure was in good agreement with that observed by X‐ray crystallography. Heat of formation in the solid phase at 298 K was predicted to be 270.3 kJ/mol. Density of TNBI was predicted to be 1.919–1.956 g/cm³ depending upon the parameter sets of group additivity method. By using these values as input data, we estimated detonation velocity and C–J pressure to be 8.69–8.80 km/s and 34.5‐36.1 GPa, respectively. Impact sensitivity of TNBI was predicted to be 33 cm.     

γ‐ and δ‐tocopherols are more effective than α‐tocopherol on the autoxidation of a 10% rapeseed oil triacylglycerol‐in‐water emulsion with and without a radical initiator

The antioxidative effects of γ‐ and mainly δ‐tocopherol in a multiphase system were hardly considered up to now. The aim of this study was i) to assess the effects and ii) to follow the degradation of α‐, γ‐ and δ‐tocopherol in concentrations of 0.01%, 0.05%, 0.1% and 0.25% during the oxidation of a 10% purified rapeseed oil triacylglycerol‐in‐water emulsion at 40 °C in the dark for 15 wk in a system containing a low oxygen concentration. Oxidation experiments were performed weekly by assessing the formation of hydroperoxides and hexanal, and the stability of the tocopherols was determined using high‐performance liquid chromatography. Storage tests were conducted with and without the addition of 0.01% α, α′‐azoisobutyronitrile (AIBN), which is a known radical initiator. α‐Tocopherol increased the formation of hydroperoxides in both tests as well as the generation of hexanal when the radical initiator was added; furthermore it was the least stable. γ‐Tocopherol delayed the formation of hexanal and prolonged the stability of the emulsion in a dose‐dependant manner. δ‐Tocopherol was the most stable and also the most effective in delaying lipid oxidation in the emulsions. Each concentration that was tested reduced the rate of hydroperoxide and especially hexanal formation. Hexanal was only formed to a slight extent after 15 wk of oxidation in the test with AIBN and the lowest dose of 0.01% δ‐tocopherol. For all tocopherols, strong correlations were found between tocopherol stability and the extent of oxidation. Results suggest that i) mainly δ‐tocopherol, but also γ‐tocopherol even less pronounced, are very good antioxidants in order to stabilize and prolong the shelf life of oil‐in‐water emulsions, ii) the antioxidative effects were intensified with increasing amounts.     

The isolation of poly(3‐hydroxybutyrate) from recombinant Escherichia coli XL1‐blue using the digestion method

This study examines the isolation of poly(3‐hydroxybutyrate) (PHB) from recombinant Escherichia coli XL1‐blue pBHB2 OLD‐2 harbouring the PHB biosynthesis gene. Six types of commercial surfactants (Emal 10P, Emal AD‐25, Emal S PASTE, Neopelex S‐S, Triton X‐100 and cetyl trimethyl ammonium bromide (CTAB)) were screened for PHB isolation by solubilising non‐polymer cellular material (NPCM) in the cell. Emal 10P, Emal AD‐25, Emal S PASTE and Triton X‐100 are suitable surfactants for PHB isolation. Factors such as the reaction temperature, reaction time, ratio of NPCM/surfactant and pH were investigated to achieve optimum conditions. For 80% of the PHB content in dry cells, the purity and recovery of the obtained PHB was 98% and 99% when 0.67 of NPCM/Emal S PASTE was used at 70°C for 30 min. The cost of the used surfactant is below 0.5 USD/kg (PHB). The pretreatment and multistage digestion method must be combined when the PHB content is lower than 80%. © 2011 Canadian Society for Chemical Engineering