Kinetic Study on Models of the Noncatalyzed Reaction Between α, ω -Dicarboxypolyamide-11 and α, ω -Dihydroxypolyoxyalkylenes

The kinetics of the noncatalyzed reaction between α, ω -dicarboxypoly-amide-11 and α, ω -dihydroxypolyoxyalkylenes is investigated by using the reactions of 11-dodecylamidoundecanoic acid with 1-dodecanol, 2-tridecanol, α-dodecyl-ω-hydroxypolyoxyethylene or α-dodecyl-ω;-hydroxypolyoxypropylene as models. Kinetic data fit a 3rd overall order (2 in acid and 1 in alcohol). Rate constants and activation parameters are determined and compared.     

Effects of solar irradiation on the properties of ethylene-norbornene composites containing solvent dyes

This study investigates the effects of irradiation with artificial solar light on the resistance to aging of ethylene-norbornene (EN) copolymer with different solvent dyes and commercial stabilizers. The mechanical properties of the samples were measured before and after ageing using tensile tests. FTIR spectroscopy was used to evaluate the carbonyl index as a measure of photooxidation after irradiation. It was found that the carbonyl index of the samples depended on the type of additive in the composite. Secondary ion mass spectrometry (TOF-SIMS) was used to analyze the chemical composition of the sample surfaces. The degree of oxidative aging was evaluated by measuring the intensities of secondary C_xH_yO_z⁺ type ions. Samples containing anthraquinone solvent dyes, such as Solvent Blue 97 or Solvent Green 28, showed the most significant improvements in durability in an aging test. Some of the applied solvent dyes showed much greater ability than the studied stabilizers to protect EN films exposed to the full solar spectrum.     

Identification of degradation products of antioxidants in polyolefins by liquid chromatography combined with atmospheric pressure photoionisation mass spectrometry

Round robin tests have revealed the trend that the concentration of stabilizers in polyolefins is usually underestimated. However, it is still unclear whether this underestimation is due to systematic errors of the analysis procedures or to degradation of the stabilizers during the production of the round robin sample itself. Within the present work, the degradation pathways of six common antioxidants (ADK Stab AO-60, Everfos 168, Kinox 30, Irganox 3114, Irganox 1076, and Cyanox 1790) were investigated. Methods based on high-performance liquid chromatography with UV detection or hyphenated with mass spectrometry (employing either an ion trap or a quadrupole/time-of-flight instrument) were developed, whereby the suitability of atmospheric pressure photoionisation was studied and compared with the performance of more established ionisation techniques like electrospray ionisation and atmospheric pressure chemical ionisation. While ADK Stab, Kinox 30, Everfos 168, and Irganox 1076 turned out to be thermally stable at 115 °C, Irganox 3114 and Cyanox 1790 were partly degraded by oxidation. In the presence of talcum, which is a widely used inorganic filler for polyolefins, additional degradation reactions such as the cleavage of ester bonds and the loss of tert-butyl groups were observed at elevated temperature.     

1,1′-Dimethylferrocene Mediated L-Glutamate Electrodes Modified With Electropolymerized 1,3-Diaminobenzene Film

Abstract

A mediated L-glutamate biosensor was constructed by incorporating 1,1′-dimethylferrocene in electropolymerized 1,3-diaminobenzene and immobilizing L-glutamate oxidase on the electropolymerized film. Stabilizers (1% DEAE-dextran, 1% MgCl₂ and 10% sucrose) were added to the immobilized enzyme to improve the long-term storage stability. The electrode responded linearly to L-glutamate concentration between 0.1 and 2.0 mM and the response of the electrode did not interfere with electroactive species and oxygen. The useful lifetime of the sensor was at least 3 weeks. When stored in dry form at 28°C, the sensor with stabilizers was stable at least 6 months. The electrode was applied to determine L-glutamate in fermentation broth samples. Good correlations were achieved between results obtained with the sensor and by enzymatic analysis using glutamate dehydrogenase.     

Coordination Polymers. IV. Physicochemical Studies on Chelate Polymers of Cr(III), Mn(II), Fe(II), Co(II), Ni(II), and Cu(II) with a Schiff Base of 4,4′-(4,4′-Biphenylylene Bisazo)di-(salicylaldehyde) with m. Toluidine

Coordination polymers of Cr(III), Mn(II), Fe(II), Co(II), Ni(II), and Cu(II) with a Schiff base derived from 4,4′ - (4,4′ -biphenylylene bisazo) di (salicylaldehyde) and m-toluidine have been prepared. All the polychelates are dark colored and insoluble in common organic solvents. Magnetic susceptibility and electronic and IR spectra of the polychelates have been studied. All the polychelates except Cu(II) show octahedral structures while Cu(II) polychelate is suggested to be a square planar.     

Application of a nanostructured supramolecular solvent for the microextraction of diphenylamine and its mono‐nitrated derivatives from unburned single‐base propellants

A supramolecular solvent made up of nano‐sized inverted hexagonal aggregates of 1‐octanol is proposed for the microextraction of diphenylamine and its mono‐nitrated derivatives in unburned single‐base propellants. The procedure included the extraction of sub‐gram quantities (30 mg) of homogenized propellant with 1.5 mL of the supramolecular solvent. Several conditions affecting extraction efficiency, for example the concentrations of the major components of the supramolecular solvent (tetrahydrofuran and alkanol), alkanol type, solvent pH, and extraction time, were investigated and optimized. The main forces for the microextraction of analytes in the nanostructured supramolecular solvent include both dispersion and hydrogen bond interactions. This mixed‐mode mechanism resulted in high extraction efficiencies reaching low method detection limits (0.005–0.012 mg/g) without the need for extract evaporation. Under the optimum conditions, recoveries in samples ranged between about 82.6 and 98.7%. Compared to the reference method, the proposed method is simple and rapid, delivering accurate and precise results, and can be applied for routine determination of diphenylamine and its derivatives in propellants. The precision of the method, expressed as relative standard deviation, was about 4.3–10.9%.     

Synthesis and characterization of chiral ruthenium(II) complexes Λ/Δ-[Ru(bpy)2(H2iip)](ClO4)2 as stabilizers of c-myc G-quadruplex DNA

In this article, two chiral ruthenium(II) complexes, Λ/Δ-[Ru(bpy)₂(H₂iip)](ClO₄)₂ (Λ-1 and Δ-1, bpy = 2,2-bipyridine; H₂iip = 2-(indol-3-yl)-imidazo[4,5f][1, 10 G.L. Duveneck, C.V. Kumar, N.J. Turro, J.K. Barton. J. Phys. Chem., 92, 2028 (1988).10.1021/j100318a064 S.K. Singh, S. Joshi, A.R. Singh, J.K. Saxena, D.S. Pandey. Inorg. Chem., 46, 10869 (2007).10.1021/ic700885m ]phenanthroline), were synthesized and investigated as c-myc G4 DNA stabilizers. The interaction of both complexes with c-myc G4 DNA has been studied using UV–vis spectra, CD spectra, and ITC experiments, and the results show that both isomers strongly bind with c-myc G4 DNA. Furthermore, the FRET melting point experiments give a ΔT_m for Λ-1 and Δ-1, which is about 9.5 and 8.3 °C, respectively, indicating that both isomers can stabilize the G-quadruplex conformation of c-myc oncogene in vitro. As a result, the replication ability of c-myc DNA, as evaluated by using PCR-stop assay, by both isomers. Besides, the inhibitory activity evaluated by MTT assay showed that Λ-1 and Δ-1 can inhibit the growth of MDA-MB-231 cells, suggesting their potential utility as inhibitors targeting to c-myc G-quadruplexe in chemotherapy.     

Chemiluminescence from poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS) block copolymers

A detailed analysis of the chemiluminescence emission (CL) from poly(styrene-b-ethylene-co-butylene-b-styrene), SEBS, was carried out. A phenol-phosphite stabilization system based on Irgafos 168 and Irganox 1330, was studied. The kinetic analysis of the CL profile under nitrogen shows a first-order reaction for the decay of chemiluminescence. The activation energy shows different values as a function of temperature, showing that different reactions are involved in the thermal degradation of the SEBS. The CL decay rate correlates well with the amount of the phosphite, Irgafos 168, and confirms the activity of this stabilizer as radical chain-breaking antioxidant in these copolymers.The isothermal analysis of CL under oxygen allows evaluation of the oxidation state, as well as the efficiency of the antioxidants. Good correlations are found between the CL parameters and concentration of Irgafos 168. Several factors suggest that oxidation begins in the interfacial region. Spectral analysis of the chemiluminescence shows the presence of different types of hydroperoxides.Finally, the characterization of the SEBS copolymers by differential scanning calorimetry reveals an order-disorder transition, assigned to aggregates that behave as paracrystalline regions.     

FUNCTIONAL POLYMERS 65. SYNTHESIS AND BRIEF CHARACTERIZATION OF SURFACE ACTIVE 2(2-HYDROXYPHENYL)2H-BENZO-TRIAZOLE ULTRAVIOLET STABILIZERS

A number of 2(2-hydroxyphenyl)2H-benzotriazoles substituted in the 5-position with reactive hydroxyl and carboxyl groups have been synthesized. They include compounds with a tert butyl substitution in the 3-position or without substitution. The latter compounds were subjected to a reaction with N-hydroxy-methyl-(meth)acrylamide to form acrylic polymerizable 3(meth)acrylamidomethyl-2(2-hydroxyphenyl)2H-benzotriaz-oles. Hydroxyl reactive compounds were allowed to react with long chain acids, compounds with carboxyl groups with long chain hydrocarbon, fluorocarbon or silicon oligomer alcohols. The polymerizable 2(2-hydroxyphenyl)2H-benzotriazoles were then copolymerized with methyl methacrylate. Films made from such polymers showed by contact angle measurements, substantial migration of the fluorocarbon or silicon component to the surface of the film.     

Aqueous Polymerization of Acrylamide Initiated by Glycolic Acid/Ce4+ Redox System

The aqueous polymerization of acrylamide initiated by the glycolic acid/Ce⁴⁺ redox system was studied in sulfuric acid medium at 35 ± 0.2°C under a nitrogen atmosphere. The initiation was carried out by the free radical generated in the decomposition of the complex formed between the oxidant and the reductant. The monomer disappearance was found to be proportional to [GA]^0,89[Ce⁴⁺]^0.57[M]^1.0, and the rate of ceric ion disappearance was found to be directly proportional to [Ce⁴⁺] and [GA] but independent of [M]. The activation energy of the system was found to be 7.21 kcal/deg/mol. The molecular weight of polyacrylamide increased with increasing [monomer] and decreased with increasing [catalyst]. The effect of pH was also studied in the pH range 2.22 to 1.44.