Improvement of wettability of hydrophobic films by impregnation of anthraquinone attached to polyoxyethylene glycol

Amphiphilic anthraquinone bearing polyoxyethylene moiety (PEG_MW‐AQ) was prepared and impregnated in polyethylene terephthalate (PET) and nylon 6 (ON) films. The uptake of PEG_MW‐AQ to PET film increased in proportion to the concentration of PEG_MW‐AQ in a bath, and the contact angle of water dropped on the film decreased with increase in the uptake. At a constant uptake of PEG_MW‐AQ, the contact angle decreased with an increase of molecular weight of PEG_MW attached to the anthraquinone, which indicates that polyoxyethylene moiety of PEG_MW‐AQ is effective on the wettability of the film. The decrement of water contact angle on PET film dyed with PEG_MW‐AQ was larger than that on ON film at the same dye uptake because of the higher dyeability of PET film than ON film with PEG_MW‐AQ. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 545–549, 2005     

Evaluation of aminoquinoline‐imprinted polymers and the recognition mechanism

Three molecularly imprinted polymers P(2‐AQ), P(3‐AQ), and P(8‐AQ) based on methacrylic acid (MAA)–ethylene glycol dimethacrylate were prepared using isomers 2‐aminoquinoline (2‐AQ), 3‐aminoquinoline (3‐AQ), and 8‐aminoquinoline (8‐AQ) as template, respectively, by non‐covalent bulk polymerization technique. Neither P(3‐AQ) nor P(8‐AQ) exhibited imprinting effect for 3‐AQ or 8‐AQ, whereas P(2‐AQ) showed significant imprinting effect for 2‐AQ. This indicates that the position of amino group on the quinoline ring has crucial influence on imprinting effect. The recognition mechanism of P(2‐AQ) was investigated extensively by such methods as selective experiments, comparative study with 2‐aminopyridine‐imprinted polymer, and effect of different kinds of mobile phases. It is confirmed that there are complementary cavities in P(2‐AQ) both in size and in the arrangement of functional groups to 2‐AQ, and MAA binds 2‐AQ via cyclic hydrogen bond. Furthermore, the influence of synthetic conditions on 2‐AQ‐imprinted polymers was explored. We found 2‐AQ‐imprinted polymer synthesized in acetonitrile porogen showed higher imprinting effect for 2‐AQ than that prepared in chloroform. It is deduced that the morphology of the former might be more favorable to 2‐AQ binding, which is also supported indirectly by the fluorimetric experiments estimating the interaction of 2‐AQ with MAA in these two porogens. Additionally, 2‐AQ‐imprinted polymers prepared using two different amounts of acetonitrile exhibited very different imprinting effects, which suggested that porogen amount used in the imprinting process exerted significant influence. In addition to the in‐depth elucidation of the recognition mechanism of 2‐AQ‐imprinted polymer, this article provides the basis for the separation and enrichment of bioactive 2‐AQ. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Facile synthesis of oxidative copolymers from aminoquinoline and anisidine

Oxidative copolymerization of 8-aminoquinoline (AQ) and o-anisidine (AS) using ammonium persulfate as oxidant was studied under various polymerization conditions and fine and uniform copolymer particles of several micrometers, determined by laser particle size and atomic force microscopic analyses, were synthesized simply. The polymerization yield, molecular weight, solubility, electroconductivity, and thermostability of the copolymers were systematically studied by changing the comonomer ratio, polymerization temperature, monomer/oxidant ratio, and acidic medium. Single chain configuration of the copolymers with various AQ/AS ratios was simulated and well related to the intrinsic viscosity. The macromolecular structure of the resulting copolymers was wholly characterized by elementary analysis, IR, UV-vis, high-resolution ¹H NMR, and solid-state high-resolution ¹³C NMR. The results show that the oxidative copolymerization of AQ and AS is exothermic. All copolymers are totally soluble in H₂SO₄, HCOOH, m-cresol but their solubility in other solvents depends significantly on the comonomer ratio, and also on the polymerization conditions. The oxidative polymer obtained is a real copolymer containing AQ and AS units rather than a mixture of two homopolymers. The AQ content calculated based on the ¹H NMR spectra of the copolymers is slightly higher than feed AQ content when feed AQ content is lower than 70 mol%. However, the AQ content calculated based on the ¹³C NMR and elementary analyses is lower than the feed AQ content when the AQ feed content is higher than 50 mol%. A peculiar dependency of molecular weight and electroconductivity of the copolymers on the AQ/AS ratio was observed. The decomposition temperature of the copolymers rises with increasing AQ content. Therefore, the thermostability of the copolymers increases with increasing AQ content due to its high aromaticity.     

Electrocatalytic reduction of oxygen at glassy carbon electrode modified by polypyrrole/anthraquinones composite film in various pH media

The electrocatalytic reduction of dioxygen by one mono and four dihydroxy derivatives of 9,10-anthraquinone (AQ) incorporated in polypyrrole (PPy) matrix on glassy carbon electrode has been investigated. The electrochemical behaviour of the modified electrodes was examined in various pH media and both the formal potential of anthraquinones and reduction potential of dioxygen exhibited pH dependence. AQ and PPy composite film showed excellent electrocatalytic performance for the reduction of O₂ to H₂O₂. pH 6.0 was chosen as the most suitable medium to study the electrocatalysis by comparing the peak potential of oxygen reduction and enhancement in peak current for oxygen reduction. The diffusion coefficient values of AQ at the modified electrodes and the number of electrons involved in AQ reduction were evaluated by chronoamperometric and chronocoulometric techniques, respectively. In addition, hydrodynamic voltammetric studies showed the involvement of two electrons in O₂ reduction. The mass specific activity of AQ used, the diffusion coefficient of oxygen and the heterogeneous rate constants for the oxygen reduction at the surface of modified electrodes were also determined by rotating disk voltammetry.     

Soda Pulping of Hardwoods Catalyzed by Anthraquinone and Methyl Substituted Anthraquinones

Abstract

Black liquor gasification (BLG) as well as the recovery of lignin and other organic compounds from pulping black liquor would be aided if an efficient sulfur‐free pulping process could be developed. This has provided new impetus for research on soda pulping with redox catalysts instead of sodium sulfide that is presently used in the kraft process. Soda/anthraquinone (AQ) pulping afforded white birch (Betula papyrifera) and sugar maple (Acer saccharum) pulps with equal if not superior strength to kraft pulps. However, the delignification rate was significantly lower for soda/AQ pulping. When AQ was replaced by 2‐methylanthraquinone (2‐MAQ) a delignification rate only slightly lower than that of kraft pulping was obtained at the same effective alkali (EA). At a kappa number of ～20, a soda/2‐MAQ pulp was produced from sugar maple at a higher yield (1.2% on chips) than for a kraft pulp. 2‐MAQ was synthesized, as a powder, at 75% yield using an AlCl₃–mediated Friedel‐Crafts reaction that is one of the methods used for commercial production of AQ.     

Comparisons between silk fibroin nonwoven electrospun fabrics using aqueous and formic acid solutions

The objective of this study is to compare the spinnability, morphology, structure, mechanical properties, and cell compatibility of the silk fibroin nanofiber nonwoven electrospun fabrics using aqueous (AQ) solution and formic acid (FA) solution. The lower limit concentration was 5?wt% and 3?wt% of AQ solution and FA solution for electrospinning, respectively. The fiber diameter of electrospun fabric using FA solution was larger than that using aqueous solution at the same concentration. The secondary structure contents of silk fabrics were same between AQ and FA solutions. FA was remained in silk nanofibers, and the remained FA could be neutralized. Young’s modulus and cell adhesion on electrospun fabric using FA was lower than that using AQ solution. On the contrary, lower cell proliferation rate on electrospun fabric using FA was kept even after neutralization.     

枫香树材清洁制浆技术

对速生阔叶木枫香树材的纤维形态、主要化学组成、清洁制浆及绿色漂白工艺进行了一系列探讨。结果显示,枫香木纤维平均长度较长,长宽比均比杨木大,且其综纤维素和戊聚糖含量高而Klason木素含量低,是一种很有发展潜力的制浆造纸原料。采用硫酸盐法制浆,蒸煮后所得细浆得率为49.9%,卡伯值为23.0,白度为23.8%ISO,黏度为734.7 mL/g。利用环境友好型漂白法——氧脱木素技术处理该枫香树材硫酸盐浆,并在此过程中创造性地使用助剂蒽醌。四因素三水平正交试验结果表明:用碱量、氧压、温度和时间对枫香树材硫酸盐浆添加蒽醌氧脱木素后浆料的性能均有很大的影响。其中,温度对得率、卡伯值、白度和黏度等的影响最大,时间对卡伯值、白度和黏度的影响最小。枫香树材硫酸盐浆添加蒽醌氧脱木素的较为适宜的工艺为:用碱量3%,氧压0.7 MPa,温度105℃,保温时间90 min,浆浓20%,MgSO4用量0.5%,蒽醌用量0.1%。在该条件下所得浆料得率90.7%,卡伯值7.0,黏度545.1 mL/g,白度51.0%ISO,脱木素选择性8.42×10-2。与相同条件下常规氧脱相比,卡伯值和白度相近,但得率、黏度和脱木素选择性都有所提高。蒽醌在枫香树材硫酸盐浆氧脱木素过程中可保护碳水化合物,提高脱木素选择性,是一种良好的氧脱木素助剂。     

The effect of polypyrrole-bound anthraquinonedisulphonate dianion on cathodic reduction of oxygen

Functionalized polypyrrole (PPy) films were prepared by incorporation of anthraquinonedisulphonate (AQDS) as doping anion during the electropolymerization of pyrrole (Py) monomer at a glassy carbon electrode from aqueous solution. The electrochemical behavior of the PPy-bound AQDS modified electrode and cathodic reduction of oxygen on the resulting polymer film were studied. An obvious surface redox reaction corresponding to AQ/H₂AQ was observed and the dependence of this reaction on the solution pH was also illustrated. The electrocatalytic ability of the PPy-bound AQDS modified electrode was demonstrated by the electroreduction of oxygen at the optimized pH of 6.3 in a phosphate buffer. The reduced AQDS (H₂AQ) is responsible for the extraordinary catalytic activity to the oxygen reduction reaction. The PPy layers not only act as an electron mediator, but also facilitate the stability of the modified electrode. It was found that the catalytic reaction occurred in the presence of the bound AQDS and O₂ is in agreement with an electrochemical–chemical (EC) mechanism. The kinetic parameters of oxygen reduction were determined using Koutecky–Levich equation and Tafel polarization technique.     

Redox chemistry of H2S oxidation by the British gas Stretford process part V: Aspects of the process chemistry

Stretford processes use air to oxidize H₂S in process and natural gases to elemental sulphur, by absorption in aqueous solution at about pH 9 and reaction of the resulting HS^– ions with dissolved oxygen, in the presence of anthraquinone disulphonates (AQDS) and vanadium (v) species, which act as catalysts. Kinetic measurements of the reactions (AQ27DS + HS^– ions), (V(v) + HS^– ions) and (AQ27DSH^– + O₂), primarily used stopped flow spectrophotometry, as reported here, following papers on the electrochemical behaviour of the individual redox couples in Stretford Processes. The course of reaction (AQ27DS + HS^– ions) was also followed with a gold bead indicator electrode, the potential of which was determined essentially by the AQ27DS/AQ27DSH^– couple as the former species were reduced to the latter. Attempts to use⁵¹V NMR to characterize aqueous vanadium-sulphur complexes were inconclusive. A possible mechanism for Stretford Processes is postulated, involving polysulphide (S _n ^2–) ions as intermediates, which are oxidized to elemental sulphur by another intermediate, H₂O₂, formed by reaction of AQ27DSH^– ions and dissolved oxygen.     

Thermal degradation of poly(vinyl chloride) in presence of additives,part II. Changes in absorption spectra

Electronic absorption spectra of PVC degraded in ethyl benzoate at 200°C in presence of maleic anhydride (MA), benzoquinone (BQ) und anthraquinone (AQ), were studied. The distribution of polyene sequence length was calculated. It was observed that the rate of formation of polyenes having 6 conjugated double bonds was reduced in presence of MA. In case of BQ and AQ, no such inhibiting effect was observed. However, formation of polyenes having a higher number of double bonds (i. e. n=8) was reduced in the presence of these additives. The ageing behaviour of the degraded polymer samples was also investigated.     

Electron Transfer Reactions in Pulping Systems (II): Electrochemistry of Anthraquinone/Lignin Model Quinonemethides

Abstract

Electron transfer reactions have been observed during the electrolyses of solutions containing anthraquinone and 8-aryl ether lignin model quinonemethides. In dry acetonitrile at a reduction potential of -0.9V (vs. Ag/AgCl) electrons are transferred from the electrode to anthraquinone (AQ) to form stable anthrahydroquinone radical anions (AHQ^?). The lignin model quinonemethides are not reduced directly at the electrode at this potential but are reduced by AHQ^? to give quinonemethide radical anions (QM^?) and AQ. The QM^? species rapidly fragment at their β-aryl ether bond to give phenolate ions and radicals; the latter further reduces to another phenolate ion. For example, the β-methyl lignin model QM 1 gives guaiacol and isoeugenol upon electrolysis at -0.9V in the presence of AQ. In wet acetonitrile, reduction of AQ at -0.9V leads to both anthrahydroquinone radical anion and dianion; the dianion is formed by direct electrolysis of the radical anion and by disproportlonation of the radical anion. Under all conditions and substrates examined, electron transfer reactions proceeded in preference to bond formation reactions which would generate “adducts.” The implication of these results Is that it should be possible to delignlfy wood by electron transfer reactions and that anthraquinone probably functions this way.     

Carbohydrate stabilization in wood by quinones and oxygen

Summary Spruce meal, impregnated with magnesium sulfate to suppress the depolymerization of the carbohydrates by oxygen, was treated with 1 M sodium hydroxide at 100°C in the presence of anthraquinone (AQ) or anthraquinone-2-sulfonic acid (AMS). A decreased loss of carbohydrates obtained in the presence of oxygen is related to an increased conversion of the reducing sugar end groups to aldonic acid end groups. Larger effects of oxygen were obtained with AMS compared to AQ.     

The pH-dependence of oxygen reduction on quinone-modified glassy carbon electrodes

The electrochemical reduction of oxygen has been studied on quinone-modified glassy carbon (GC) electrodes as a function of solution pH using the rotating disk electrode (RDE) technique. The surface of GC was grafted with anthraquinone (AQ) and phenanthrenequinone (PQ) by electrochemical reduction of their diazonium derivatives and the oxygen reduction measurements were carried out at different pHs (pH 7-14). The redox-potentials of surface-bound quinones were determined using cyclic voltammetry (CV). The kinetic parameters of oxygen reduction on GC/AQ and GC/PQ electrodes were determined considering a surface redox catalytic cycle model for quinone-modified electrodes.     

苯酐法合成蒽醌固体酸催化剂的进展

蒽醌(AQ)是重要的有机合成中间体,采用固体酸催化剂代替传统的液体酸催化剂可以使蒽醌合成过程绿色环保。笔者对固体酸催化剂硅-铝酸盐、粘土矿物、金属氧化物、分子筛、杂多酸催化剂、阳离子交换树脂应用于蒽醌合成的研究进展进行了综述,认为固体酸催化剂对蒽醌合成有很好的研究前景。     

麦草亚铵法氧脱木素浆蒽醌强化次氯酸盐漂白

对麦草亚铵法氧脱木素浆进行蒽醌强化的次氯酸盐漂白工艺的研究,结果表明:在所选四因素三水平漂白工艺中,影响纸浆白度和卡伯值的主要因素是用氯量,当用氯量为7%时,纸浆白度为71.1%ISO;另外,在50℃和80℃的条件下,对麦草亚铵法氧脱木素浆分别进行添加氨基磺酸和蒽醌的漂白研究,发现次氯酸盐漂白时添加蒽醌比添加氨基磺酸的漂白效果好,不仅漂白浆的白度和黏度均得到提高,而且脱木素能力也显示加强。     

Effect of molecular grafting on the pore size distribution and the double layer capacitance of activated carbon for electrochemical double layer capacitors

High specific surface carbon (Black Pearls 2000) has been modified by electroactive anthraquinone (AQ) groups by spontaneous reduction of the corresponding in situ generated diazonium derivative. A set of modified carbons with different AQ loadings have been synthesized to study the effect of the grafted groups on the pore texture and on the double layer capacitance of the modified carbons. Grafting of a small amount of AQ molecules caused a significant loss of the BET surface area and affected mainly the ultramicroporosity of the carbon powder. A correlation of the pore texture with the electrochemical data allows to conclude that pores smaller than 0.65 nm do not significantly contribute to the double layer capacitance in H₂SO₄ electrolyte and therefore are not efficiently accessible to the ions of this electrolyte. Above an AQ loading of 7 wt.%, both microporosity and mesoporosity are strongly affected but the decrease of double layer capacitance seems to be directly related to the coverage of the carbon surface by AQ molecules.     

Composite films of poly-(ester-sulphonated) and poly-(3-methylthiophene) for ion-exchange voltammetry in acetonitrile solutions

This paper describes the preparation and characterisation of a polymeric electrode coating based on a composite of the poly-(ester-sulphonated) Eastman AQ55^® (AQ55) and poly-(3-methylthiophene) (PMeT), which is used for the controlled uptake and partial release of electroactive cations in acetonitrile solutions. The film is prepared by electrochemical oxidation in acetonitrile of 3-methylthiophene on glassy carbon disks or Pt-quartz crystal electrodes pre-coated with a thin film of AQ55.The electropolymerisation process is controlled so that the overall number of positive charges of oxidised PMeT is equal to the number of negative charges of the sulphonate groups of AQ55. Cyclic voltammetry and quartz crystal microbalance measurements indicate that the AQ55/PMeT mixed film is stable in acetonitrile and that its cation-exchange properties depend on the applied potential. When the PMeT moieties are reduced, the film incorporate cations; following electrochemical oxidation of the coating causes a release of the incorporated cations which, however, is only partial.Scanning electron microscopy (SEM) examination of cross sections of the composite polymer layer indicate that it is really a bi-layer, made by an inner compact layer of AQ55 on which a thicker and porous PMeT layer is grown. The outer PMeT layer acts as a barrier whose ionic charges can be changed electrochemically from positive (oxidation) to neutral (reduction). These ionic charges hinder or allow, respectively, the permeation of redox cations which tend to interact with the negatively charged sulphonic sites of the AQ55 layer. Direct self-neutralization of part of the positive charges of oxidized PMeT by the AQ55 sulphonic groups allows the release of part of the redox cations incorporated previously in the mixed film when PMeT is in the reduced state. By operating in acetonitrile solutions without added electrolyte it is possible to increase the fraction of redox cations which are released in consequence of the oxidation of PMeT; this suggests a slower and only partial oxidation of PMeT under such experimental conditions.     

Structural/Reactivity Studies (II): Reactions of Lignin Model Compounds with Pulping Additives

Abstract

Lignin model compounds, capable of forming quinonemethides and having different substituents on the quinonemethide (A) rings and β-aryl ether (B) rings, have been degraded under a variety of conditions in the presence of NaOH (soda), NaOH/Na₂S (kraft), NaOH/glucose, and NaOH/AHQ (soda/AQ). Substituent changes on ring B had no effect on the extent of model fragmentation in the presence of excess AHQ and NaSH. Substituent changes on ring A had large effects on fragmentation under soda/AQ and kraft conditions. These substituent-reactivity relationships indicate that the slow step in the mechanism for model fragmentation under soda/AQ and kraft conditions is quinonemethide formation. Conditions aimed at demonstrating the existence of electron-transfer fragmentation of the model compounds gave results which were inconclusive, but demonstrated that equilibrium reactions between quinonemethide intermediates exist.     

Anthraquinone Losses During Alkaline Pulping

Extensive loss of anthraquinone (AQ) or the active catalyst anthrahydroquinone (AHQ) from the AQ –- AHQ catalytic cycle has been explained in part by side reactions leading to the reaction product anthrone (anthracen-9-one), followed by subsequent formation of adducts with lignin quinone methides. Degradation of an adduct between anthrone and the quinone methide of guaiacylglycerol-β-guaiacyl ether, under soda pulping conditions, resulted in a complex mixture of products. The mixture included 3-guaiacylbenzanthrone, bianthronyl, bianthrone, guaiacol, AQ, trans-coniferyl alcohol, trans-coniferylaldehyde, cis- and trans-1-(3-methoxy-4-hydroxyphenyl)-2-(2-methoxyphenoxy)ethene, vanillin, and 2-methoxy-4-vinylphenol. C-13 NMR studies of lignins isolated from soda/AQ spent liquors indicated the presence of residual anthrone adducts and a significant content of chemically attached AQ.     

新型光稳定剂产品应用于水性醇酸涂料的研究

醇酸树脂普遍应用于工业涂料,其暴露在自然太阳光时,容易造成外观上颜色的变化和涂层劣化与粉化,目前这层保护主要是添加紫外线吸收剂(UVA)和酸性系统使用受阻胺光稳定剂(N-OR HALS)来达成。由于环保趋势,水性醇酸涂料已发展成为解决有关一般常用传统高VOC溶剂型涂料,它能够有效减少或不使用溶剂的优点,而环保型涂料所遭遇的挑战之一,是需要光安定剂来保护涂料预防光劣化产生。先针对2种不同类型水性受阻胺光稳定剂N-R HALS(高碱性)和N-OR HALS(弱碱性)混合水性醇酸涂料测试,试验结果显示:N-OR HALS适用于水性醇酸涂料系统。本文主要是有关于应用试验设计(DOE)试验手法,根据实验室人工加速老化试验结果显示,增加水性紫外线吸收剂Eversorb AQ6和水性受阻胺光稳定剂(NOR-HALS)Eversorb AQ5在水性涂料中的有效浓度,可以增强相对的保护效果,试验数据显示膜厚对减缓黄变影响而言也是显著因子,但效果不如添加水性光稳定剂产品有效。