Enhancing the Anhydrous Proton Conductivity of Sulfonated Polysulfone/Polyvinyl Phosphonic Acid Composite Membranes With Hexagonal Boron Nitride

Hexagonal boron nitride (h-BN) particles have attracted increasing interest due to mechanical properties, chemical stability, electrical features, thermal stability, and good lubrication property. In this work hexagonal boron nitride were used as inorganic fillers, which increase the mechanical and thermal stabilities of the membrane. The proton conducting polymer membranes were prepared by blending of sulfonated polysulfone, polyvinyl phosphonic acid, and boron nitride. Scanning electron microscopy indicated the homogeneous distribution of hBN nanoparticles in the polymer matrix. hBN increased the proton conductivity and in the anhydrous state the maximum proton conductivity was determined as 7.9 × 10^?3 S/cm at 150°C for PVPA-SPSU-5hBN.     

Synthesis of Proton Exchange Membranes with Pendent Phosphonic Acid Groups by Irradiation Grafting of VBC

Proton exchange membranes with pendent phosphonic acid groups were synthesized by pre‐irradiation grafting from vinylbenzyl chloride onto FEP and ETFE films with subsequent Arbuzov phosphonation. Free phosphonic acid groups, which are necessary for proton conductivity, were obtained by acid ester hydrolysis. The phosphonated membranes were characterized by phosphonation degree, FTIR‐spectroscopy, ion exchange capacity (IEC), oxidation stability, swelling properties, and thermal properties (TGA).     

POE熔融挤出接枝MAH的研究

采用熔融法制备POE接枝MAH，利用红外光谱对其结构进行表征。考察了MAH和过氧化二异丙苯（DCP）用量对接枝率及熔融指数的影响。实验结果表明，MAH用量增加，接枝率逐渐增大，熔体流动速率逐渐下降；随着引发剂用量的增加，接枝率也随之增加，熔体流动速率却显著下降。同时对POE接枝MAH的机理进行了探讨。     

A Tetrahedral Boronic Acid Diester Formed by an Unnatural Amino Acid in the Ligand Pocket of an Engineered Lipocalin

Boronic acids have long been known to form cyclic diesters with cis-diol compounds, including many carbohydrates. This phenomenon was previously exploited to create an artificial lectin by incorporating p-borono-l -phenylalanine (Bpa) into the ligand pocket of an engineered lipocalin, resulting in a so-called Borocalin. Here we describe the X-ray analysis of its covalent complex with 4-nitrocatechol as a high-affinity model ligand. As expected, the crystal structure reveals the formation of a cyclic diester between the biosynthetic boronate side chain and the two ortho-hydroxy substituents of the benzene ring. Interestingly, the boron also has a hydroxide ion associated, despite an only moderately basic pH 8.5 in the crystallization buffer. The complex is stabilized by a polar contact to the side chain of Asn134 within the ligand pocket, thus validating the functional design of the Borocalin as an artificial sugar-binding protein. Our structural analysis demonstrates how a boronate can form a thermodynamically stable diester with a vicinal diol in a tetrahedral configuration in aqueous solution near physiological pH. Moreover, our data provide a basis for the further engineering of the Borocalin with the goal of specific recognition of biologically relevant glycans.     

Grafting of Poly(methyl methacrylate) Brushes from Magnetite Nanoparticles Using a Phosphonic Acid Based Initiator by Ambient Temperature Atom Transfer Radical Polymerization (ATATRP)

Poly(methyl methacrylate) in the brush form is grown from the surface of magnetite nanoparticles by ambient temperature atom transfer radical polymerization (ATATRP) using a phosphonic acid based initiator. The surface initiator was prepared by the reaction of ethylene glycol with 2-bromoisobutyrl bromide, followed by the reaction with phosphorus oxychloride and hydrolysis. This initiator is anchored to magnetite nanoparticles via physisorption. The ATATRP of methyl methacrylate was carried out in the presence of CuBr/PMDETA complex, without a sacrificial initiator, and the grafting density is found to be as high as 0.90 molecules/nm². The organic–inorganic hybrid material thus prepared shows exceptional stability in organic solvents unlike unfunctionalized magnetite nanoparticles which tend to flocculate. The polymer brushes of various number average molecular weights were prepared and the molecular weight was determined using size exclusion chromatography, after degrafting the polymer from the magnetite core. Thermogravimetric analysis, X-ray photoelectron spectra and diffused reflection FT-IR were used to confirm the grafting reaction.     

二甲苯对聚丙烯熔融接枝衣康酸的影响

通过熔融接枝技术采用反应型双螺杆挤出机制备了可反应性相容剂聚丙烯接枝衣康酸（PP-g-ITA），研究了二甲苯（DMB）对接枝物性能的影响。采用热重分析（TG）和傅立叶变换红外光谱（FTIR）对接枝物结构进行了分析；采用非水滴定法对接枝物的接枝率（GR）进行了测定。结果表明：ITA已经接枝到PP大分子链上，ITA的引入导致接枝物熔点（Tm）和热分解温度（Td）略有改变；DMB对GR影响较大，其作用类似于苯乙烯（St），但却不参与反应。当PP／ITA／DMB／DCP=100/8／10／0.8时，GR高达1.63％。     

含多醚膦酸水处理药剂配方试验研究和应用

介绍了含多醚膦酸水处理药剂配方试验研究和应用过程，并概括了该配方的特点。     

Development of Functional Adsorbent From Textile Cotton Waste by Radiation Induced Grafting Process: Equilibrium and Kinetic Studies of Acid Dye Adsorption

An environment benign-aqueous solvent based-single step-radiation induced grafting process was used to graft Poly(vinylbenzyltrimethyl ammonium) chloride (PVBT) onto cellulosic cotton textile waste to transform it into a valuable cationic adsorbent (PVBT-g-Cellulose). The PVBT-g-Cellulose adsorbent was characterized by grafting yield determination, elemental analysis, scanning electron microscope (SEM), and fourier transformed infrared (FTIR) spectroscopy. The PVBT-g-Cellulose adsorbent, investigated for the removal of model dyes from manufactured solutions, exhibited equilibrium adsorption capacities of ～540 mg/g, ～474 mg/g, and ～122 mg/g for acid blue 25(AB25), acid yellow 99(AY99), and acid blue 74(AB74), respectively. The degree of agreement between the adsorption isotherm models and experimental data followed the order: Langmuir-Freundlich>Redlich-Peterson>Langmuir>Freundlich. The kinetic adsorption data was found to be in close agreement with pseudo-second order kinetic model. The elution percentage of as high as ～95% could be achieved for AB25 using a suitable eluent.     

Enhancing the Interfacial Properties of Composites by Grafting Polyethylene Glycol and Polyvinyl Alcohol Onto a CF Surface

In this study, a carboxy esterification reaction was used to graft the hydrophilic polymers polyethylene glycol (PEG) and polyvinyl alcohol (PVA) onto the surface of carbon fibers (CFs). The properties of the grafted CFs were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), X‐ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TG) and through the measurement of interlaminar shear strength (ILSS). SEM enabled the graft morphology on CF surfaces to be determined. In comparisons of grafted and non‐grafted CFs, AFM indicated that the roughness was significantly improved; XPS showed that the concentration of oxygen‐containing functional groups increased by 186.1%; TG showed that the grafting rate of CF‐grafted PEG (CF‐g‐PEG) was 0.5%, and that of CF‐grafted PVA (CF‐g‐PVA) was 2.0%; and the ILSS of CF‐g‐PEG and CF‐g‐PVA increased by 22.7% and 43.0%, respectively. We conclude that esterification grafting is an effective method for modifying the physicochemical properties of CFs and improving the interfacial adhesion of composites. POLYM. ENG. SCI., 59:1043–1050, 2019. © 2019 Society of Plastics Engineers     

无水氢氟酸生产工艺过程及环境影响分析

以萤石粉、硫酸作为原料生产无水氢氟酸的工艺介绍,定量地分析了废气、固体废物、废水的产生量,提出了减缓环境影响的措施。无水氢氟酸生产过程产生的各大气污染物,经处理后可达标标排放;生产过程产生的废水经物化法处理,可达标排放;各设备噪声采取相应减震、减噪措施,厂界噪声可达标排放;固体废物可综合利用。     

无水氢氟酸生产中换热设备的故障分析和防范措施

主要介绍无水氢氟酸生产中换热器发生的故障,并分析其故障原因,提出防范措施。     

利用手持技术比较强酸弱酸的pH和电导率

利用手持技术仪器探究盐酸(HCl)和醋酸(HAc)两种不同强度的酸在相同条件下的pH和电导率,把抽象思维转化为直观数据,通过直观数据鲜明地比较它们之间的区别,从而更进一步让学生清楚地比较强酸和弱酸电离时pH和电导率的差别,认识溶液的导电性强弱与溶液中总离子数的多少有密切的联系,以及弱酸溶液是无法完全电离的这一理论知识。     

Enhancing the Efficiency and Regioselectivity of P450 Oxidation Catalysts by Unnatural Amino Acid Mutagenesis

The development of effective strategies for modulating the reactivity and selectivity of cytochrome P450 enzymes represents a key step toward expediting the use of these biocatalysts for synthetic applications. We have investigated the potential of unnatural amino acid mutagenesis to aid efforts in this direction. Four unnatural amino acids with diverse aromatic side chains were incorporated at 11 active‐site positions of a substrate‐promiscuous CYP102A1 variant. The resulting “uP450s” were then tested for their catalytic activity and regioselectivity in the oxidation of two representative substrates: a small‐molecule drug and a natural product. Large shifts in regioselectivity resulted from these single mutations, and in particular, for para‐acetyl‐Phe substitutions at positions close to the heme cofactor. Screening this mini library of uP450s enabled us to identify P450 catalysts for the selective hydroxylation of four aliphatic positions in the target substrates, including a C(sp³)?H site not oxidized by the parent enzyme. Furthermore, we discovered a general activity‐enhancing effect of active‐site substitutions involving the unnatural amino acid para‐amino‐Phe, which resulted in P450 catalysts capable of supporting the highest total turnover number reported to date on a complex molecule (34 650). The functional changes induced by the unnatural amino acids could not be reproduced by any of the 20 natural amino acids. This study thus demonstrates that unnatural amino acid mutagenesis constitutes a promising new strategy for improving the catalytic activity and regioselectivity of P450 oxidation catalysts.     

顺丁烯二酸酐及其衍生物溶液接枝改性聚苯乙烯的研究

文章介绍了分别将顺丁烯二酸酐，顺丁烯二酸一丁酯和顺丁烯二酸二丁酯与聚苯乙烯的二甲苯溶液在过氧化二苯甲酰引发下的接枝反应，讨论了反应单体浓度、引发剂用量接枝率的影响，测试了接枝物的成膜性能。     

水中常见阴离子和有机酸的离子色谱分析方法研究

建立了同时测定水样中常见阴离子和有机酸的电导抑制-离子色谱分析方法。以阴离子交换色谱柱(IonPac AS11)(250mm×4.0mm)和IonPac AG11(50mm×4.0mm)为分离柱和保护柱,进样25μL,以7.5mmol/L NaOH为淋洗液,0.7mL/min的流速淋洗,抑制电导检测。分析测定了水样中氯乙酸、Cl-、NO-2、NO-3、琥珀酸、酒石酸、SO2-4、草酸的含量。结果表明:该方法在20min内能完成分析检测;加标回收率值为72.25%~109.69%,相对标准偏差(RSD)值5%。通过该方法分析检测了昆明市呈贡新区河流水和湖泊水,结果较为满意。     

Grafting of 4‐Hydroxybenzenesulfonic Acid onto Commercially Available Poly(VDF‐co‐HFP) Copolymers for the Preparation of Membranes

The grafting of a phenate bearing sulfonate group in solution onto commercially available poly(VDF‐co‐HFP) copolymers, where VDF and HFP stand for vinylidene fluoride and hexafluoropropene, respectively, is presented. This reaction leads to novel fluoropolymers, bearing aryl sulfonic acid side functions, which are fuel cell membrane precursors. A mechanism similar to the grafting of bisphenol onto VDF‐containing copolymers is discussed. First, the sulfonate phenate is modified to give the didecyldimethylammonium bromide sulfonate phenate salt, in order to promote the substitution onto a fluorine atom in VDF unit adjacent to one HFP unit onto a fluorine atom in the copolymer. The substitution of this salt onto the fluorinated copolymer yields low molar percentages of grafted phenate, ranging from 1.8 to 5.1 mol‐%, whereas it reaches values up to 13 mol‐% grafting when the NH₂‐CH₂‐CH₂‐S‐CH₂‐CH₂‐C₆H₄‐SO₃Na amine is used as the grafting agent. NMR characterization is used to monitor the grafting process. The electrochemical properties of the resulting phenate grafted‐poly(VDF‐co‐HFP) copolymer are studied. The theoretical ion exchange capacities are half that of Nafion®. The proton conductivities are also lower than that of Nafion®, although one conductivity measurement reached a value of 5.1 mS cm^–1, showing a non‐negligible conductivity. The water uptake is lower than these noted for a sulfonated amine‐grafted copolymer, and is of the same order as that for Nafion®. Finally, it is shown that these novel materials start to decompose above 200 °C, showing a similar thermostability as that of an amino‐containing aryl sulfonate‐grafted poly(VDF‐co‐HFP) copolymer.     

Removal of Acetic Acid by Absorption from Stream Recycle Ethylene in the Ethylene and Vinyl Acetate Copolymers Process

Abstract

In the EVA copolymers process (ethylene and vinyl acetate copolymers), the stream recycle ethylene contains vinyl acetate and acetic acid as impurities. It is necessary to remove the acetic acid to increase the quality of the final product. The removal of acetic acid by absorption with differents solvents has been investigated. Mass transfer coefficients needed for absorber simulation and design were obtained. The experimental data indicate that the resistance of a liquid film to mass transfer is practically negligible when using water and vinyl acetate as solvents. The absorber was simulated by using a nonequilibrium model which reproduced the experimental results to deviations of less than 20%.     

利用浓硫酸和无水ZnCl2催化合成3-氯-7-羟基-4-甲基-香豆素

为了减少环境污染和设备腐蚀,采用浓硫酸和无水ZnCl2二元催化剂代替单一浓硫酸催化间苯二酚和2-氯乙酰乙酸乙酯合成3-氯-7-羟基-4-甲基-香豆素.小试结果表明,当n(ZnCl2)/n(间苯二酚)为0.2时,浓硫酸用量可降低40％,所得香豆素含量为92％,比单一浓硫酸工艺(91％)略高;收率79％,比单一浓硫酸工艺提高7个百分点.二元催化剂合成法优势明显,具备应用前景.     

ZnO包覆A12O3填充环氧树脂的导热与介电性能

采用溶胶-凝胶法制备出ZnO包覆A12O3的复合粉体,并将其添加入环氧树脂中,研究其热导率和介电常数.结果表明,发现经550℃煅烧2h后,产物的包覆层从水合草酸锌被缎烧成为ZnO;ZnO峰形尖锐,结晶良好,ZnO较好地包覆在A12O3周围.ZnO包覆A12O3的复合粉体添加到环氧树脂后,其热导率得到明显改善,且介电常数仍维持在较低水平(小于5).     

黄原胶辐射接枝丙烯酸及其耐盐性研究

以60Coγ为辐射源,对黄原胶(XG)和丙烯酸(AA)进行共辐射制备黄原胶/丙烯酸接枝共聚物(XG-g-PAA)。研究了合成条件对产品接枝性及吸水性的影响,并和化学引发得到的接枝物的吸水性及耐盐性进行了比较,用红外光谱及电镜扫描对产品结构进行了表征。结果表明,产品接枝率为130.8%,接枝效率为82.4%,吸去离子水率为815 g/g。它在去离子水、人工尿及质量分数均为0.9%的NaCl水溶液、BaCl2水溶液、FeCl3水溶液、Na2SO4水溶液、尿素水溶液中的吸水率,较经化学引发得到的接枝物分别提高了45.3%、27.3%、20.6%、16.7%、10.2%、20.7%、44.9%。SEM表明,辐射引发较化学引发更易得到多孔疏松的产品,该产品是农用保水剂及卫生用品的良好候选材料。