疏水缔合水溶性聚合物的合成与表征

综述了疏水缔合型水溶性聚合物合成与表征方法，介绍了在合成过程中提高油溶性单体和水溶性单体混溶性的方法，简述了疏水物质含量的核磁共振、紫外光谱、裂解气相色谱等测定方法。     

Quantitative assessment of alkyl chain branching in alcohol-based surfactants by nuclear magnetic resonance

Surfactants with branched hydrophobes have gained considerable interest, since these can be used in formulations for laundry cleaning at a wide range of conditions. The claims range from improved dissolution rate to hardness tolerance and stain removing efficacy. In contrast to the historically known heavily branched surfactants, novel branched surfactants are less compromised by increased biodegradability. These properties find their basis in the structural characteristics of the hydrophobe, such as number, position, and type of alkyl chain branches. Our current understanding of structure-property relations, however, is hampered by the lack of generic methodology needed to obtain structural data on hydrophobe branching. A nuclear magnetic resonance (NMR) approach was developed by which we could obtain a comprehensive set of quantitative hydrophobe branching parameters in alcoholbased surfactants. The ¹³C and ¹H NMR spin systems of hydrophobe branched species were assigned by means of twodimensional NMR techniques. These assignments allowed the quantitative assessment of these branched species by straight-forward signal integration in the ¹H and ¹³C NMR spectra. The quantified NMR data can be used to understand product performance and the biodegradation of surfactants with branched hydrophobes.     

Viscosity characteristics of aqueous solutions of block copolymers of propylene and ethylene oxides

Brookfield viscosity measurements were made on aqueous solutions of surface-active agents composed of block copolymers of propylene and ethylene oxides in which the molecular weights of the polymers varied from 1100 to over 15,000. The hydrophobia bases were polyoxypropylene glycols varying in molecular weight from 940 to 4000. To these were added varying amounts of ethylene oxide so that the polyoxyethylene hydrophil comprised from 15 to 80% of the surfactant total weight. This work has materially expanded previous viscosity studies of aqueous solutions of nonionic surfactants by using a unique type of hydrophobe, two ethylene oxide chains, and far higher molecular weights of hydrophobe and of hydrophil, up to 280 moles of ethylene oxide. The surface-active agents with hydrophobe base molecular weights from 940 to 1100, and in which the polyoxyethylene sections comprised from 15 to 80% of the total weight, did not form gels in aqueous solution. Some surfactants with a hydrophobe base molecular weight of 1750 to 2750, to which varying amounts of polyoxyethylene were added, formed gels in water at a surfactant concentration range of 40% to 80%. With a hydrophobe molecular weight of 3250, gels formed at from 30% to 90% surfactant concentration, while with one nonionic derived from a 4000 molecular weight hydrophobe, a gel formed at only 20% polyol concentration. Two viscosity maxima were found in some cases, as reported occasionally for other systems. An increase in temperature from 0C to 50C generally reduced the viscosity of systems based on hydrophobes of 1175 and lower molecular weights, and increased it in systems based on hydrophobes of 1750 and higher molecular weights. The behavior of these surfactants in forminggels is explained on the basis of hydrogen bonding, micellar aggregation and water entrapment. The moles of water per ethylene oxide group in the adduct varied with the hydrophobe base weight and with the polyoxyethylene hydrophil, and within systems showing maximum viscosities, ranged from 0.3 to 17.1, at 25C, which is much higher than observed in other nonionics.     

Combined Gel Permeation Chromatography—NMR Techniques in the Characterization of Petroleum Residuals

Abstract

It has been shown that proton nuclear magnetic resonance spectra of fractions obtained by gel permeation Chromatography techniques can yield significant information in the characterization of petroleum residuals. Application of empirical relationships developed for the analysis of NMR spectra is shown to be useful when applied to gel permeation Chromatography fractions. Whole residues and a deasphaltened fraction have been separated and studied. Unit weights and aromaticities have been obtained by NMR and compared with molecular weights from vapor pressure osmometry measurements. In addition, supplemental information from infrared and mass spectrometry on GPC fractions has been used to characterize a “neutral” portion of the residue.

Adsorption effects have caused an apparent shift in aliphatic and aromatic components as observed by NMR spectra suggesting that information relating to the mechanism of GPC separations, particularly in regard to factors other than molecular size which influence elution rates, might be obtained from petroleum residual characterizations.     

Rheological properties of a hydrophobically modified anionic polymer: Effect of varying salinity and amount of hydrophobic moieties

Hydrophobically modified polyelectrolytes have been suggested as an alternative to the more commonly used polyelectrolytes in enhanced oil recovery (EOR) applications involving polymers. Compared to regular polyelectrolytes, the hydrophobically modified polyelectrolytes are known to be more stable at high salinities. In this study, we have investigated the influence of brine salinity and ionic composition for a series of six hydrophobically modified polyelectrolytes with the same polymer backbone, but with an increasing average number of hydrophobic groups per polymer molecule. Polymer characterization has been performed using a combination of steady‐state shear viscosity and dynamic oscillatory measurements. Hydrophobic interactions leading to a change in rheological properties was only observed above a threshold value for the concentration of hydrophobe. At the threshold value, salt‐induced hydrophobic interactions were observed. For higher concentrations of hydrophobe, high salinity solutions showed one order of magnitude increase in viscosity compared to the polymer without hydrophobic groups. This could partly be explained by an increase in elasticity. These findings have important implications for polymer selection for EOR. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43520.     

Phase diagrams of urethanized polyvinyl alcohol with a series of hydrophobically modified pH-responsive polymers containing amino acid residues

The composition and phase diagram of aqueous two-phase systems (ATPSs) of urethanized polyvinyl alcohol (UPVA) and a series of ionic co- and terpolymers (IPs) of pH-responsive hydrophilic diallylammonioethanoate, 0–3mol% hydrophobic dodecyldiallylammonium chloride, and SO₂ have been studied for the first time. The presence of unquenched nitrogen valency in the repeat units of the IPs permitted the change of the charge types and their densities in the polymer chain. The effects of zwitterionic (Z^±) and anionic (A^?) charge densities on the polymer backbone, salt (NaCl) concentration, and hydrophobe content on the phase diagrams were investigated. The presence of the hydrophobe in the polymer shifted the binodal downward; magnitude of the shift increased with the increase in the hydrophobe content. The phase separation happened at relatively low total polymer concentrations (much below than 10%), which could be useful in separation and purification of biomaterials.     

一种新型硫醇菊酯衍生物的合成修饰及其抗蚊杀虫活性

拟菊酯类杀虫剂具有高效、低毒、用量少、低残留和广谱性等优点,因而受到广泛使用。采用化学修饰方法合成一种含氟的硫醇菊酯衍生物,其结构表征通过1H NMR、~(13)C NMR确定。抗蚊杀虫测试表明:该化合物对白纹伊蚊幼虫的半致死浓度LC50值为11.55μmol/L,且在12.5μgobottle-1的30 min作用下对白纹伊蚊雌性成蚊,其致死率能够达到74%。     

新型乳胶漆用疏水剂的研制

本以有机硅和石蜡为主要原料，制备了一种乳液型乳胶漆用疏水剂。评价了疏水剂的稳定性及其他性能指标，讨论了其对涂料性能的影响。结果表明，将该疏水剂作为一种功能性组分加入到乳胶漆体系中，能够大大地提高乳胶漆的耐沾污性、耐洗刷性和耐候性：     

NMR characterisation of dicyclopentadiene resins and polydicyclopentadienes

Dicyclopentadiene (DCPD) thermosetting resin has been characterized by nuclear magnetic resonance (NMR) technique. The main monomer in DCPD resin is found to be in endo isomer form. Solid-state ¹³C cross polarization/magic angle spinning and ¹³C high-power decoupling NMR techniques have been applied for characterization of polymer network during curing and after cure. NMR spectra of carbon atoms in rigid phase and in mobile phase have been investigated. The possibility of three structural elements in polymer network was discussed. Solid-state NMR technique was applied to study of poly-DCPD oxidation. © 1996 John Wiley & Sons, Inc.     

Surfactant co-thickening in model associative polymers

Associative thickeners act to thicken aqueous systems through the formation of non-specific hydrophobe associations. The formation of these ‘pseudomicellar’ units is driven by the exclusion of the thickener hydrophobes from the aqueous phase, a phenomenon greatly enhanced by the presence of the appropriate level and type of non-ionic surfactant. This enhancement of hydrophobic association is accompanied by a dramatic increase in solution viscosity, commonly referred to as surfactant co-thickening. The selection of an ‘appropriate’ surfactant is dictated by the solubility of the surfactant in the system which is in turn controlled by temperature, the nature of the surfactant hydrophobe, the degree of ethoxylation and the presence of co-solvents.     

Characterization of β-Silicon Carbide by Silicon-29 Solid-State NMR, Transmission Electron Microscopy, and Powder X-ray Diffraction

Increased interest in ceramic materials, particularly for high-temperature, high-stress applications, has created the need for rapid and reliable analytical techniques to monitor microcrystalline structure of commercial ceramic powders. A comparative evaluation of commercially available β-SiC powders is undertaken to analyze the potential of nuclear magnetic resonance (NMR) in the characterization of β-SiC powder. NMR provides an acceptable, rapid method for characterization of powders both during powder manufacturing as well as for powder analyses priror to sintering studies. The results of transmission electron microscopy and X-ray diffraction are correlated with the NMR spectra to explain some newly observed features in the NMR spectra of β-SiC powders and to illustrate the sensitivity of NMR to microcrystalline disorder.     

Application of NEAT for the simulation of liquid–liquid extraction processes with poorly specified feeds

The conceptual design of fluid separation processes is particularly challenging if the considered mixtures are poorly specified, since classical thermodynamic models cannot be applied when the composition is unknown. We have recently developed a method (NEAT) to predict activity coefficients in such mixtures. It combines the thermodynamic group contribution concept with the ability of NMR spectroscopy to quantify chemical groups. In the present work, we describe how NEAT can be applied to equilibrium stage simulations of liquid–liquid extraction processes with poorly specified feeds. Only a single ¹³C NMR spectrum of the feed is needed for predicting the distribution of a target component for different process parameters, such as temperature or extracting agent. The predictions from several test cases are compared to results that are obtained using the full knowledge on the composition of the feed and surprisingly good agreement is found.     

Synthesis and rheological properties of hydrophobically modified poly(vinyl alcohol)

A novel series of water-soluble hydrophobically modified poly(vinyl alcohol) (HMPVA) with various hydrophobe contents was prepared by grafting poly(vinyl alcohol) (PVA) using 1-dodecanol and toluene-2,4-diisocyanate as hydrophobic monomer and coupling agent, respectively. The chemical structure of HMPVA was analyzed by Fourier Transform Infrared Spectrometer (FTIR) and ¹H NMR. Rheological properties of the aqueous solutions also confirmed the incorporation of hydrophobic groups into PVA. In dilute concentration regime, HMPVAs exhibited lower intrinsic viscosity than PVA, suggesting that HMPVA molecules were more shrunken. While the aqueous solution viscosity was enhanced due to hydrophobic modification at a high concentration, and HMPVAs with higher hydrophobe contents exhibited lager values of apparent viscosities. Over a frequency range of 1 to10² rad/s, the dynamic storage modulus of PVA solution was smaller than the dynamic loss modulus whereas the dynamic storage modulus of HMPVAs solutions was greater than the dynamic loss modulus, indicating the evolution of viscoelastic solid properties in HMPVAs solutions. The yield stress of PVA was nearly zero whereas that of HMPVAs represented positive values, implying that networks were present in HMPVAs solutions.     

恩诺沙星纯度标准物质的定量核磁定值研究及其不确定度评估

采用定量核磁法对恩诺沙星标准物质进行纯度定值研究,考察了定量核磁中选择不同定量峰的定值结果,并系统评估了定量核磁法引入的定值不确定度。同时采用质量平衡法对恩诺沙星纯度进行定值。结果表明,恩诺沙星纯度标准物质核磁定值结果为99.7%,核磁定值不确定度为0.5%。     

1H low- and high-field NMR study of the effects of plasma treatment on the oil and water fractions in crude heavy oil

The chemical and physical properties of a Brazilian heavy oil submitted to plasma treatment were investigated by ¹H low- and high-field nuclear magnetic resonance (NMR) combined to the characterization of rheological properties, thermogravimetry and measurement of basic sediments and water (BSW) content. The crude oil was treated in a dielectric barrier discharge plasma reactor, using natural gas, CO₂ or H₂ as working gas. The results indicated a large drop in the water content of the plasma-treated samples as compared to the crude oil, giving rise to a reduction in the viscosity. No significant chemical change was produced in the oil portion itself, as observed by ¹H NMR. The water contents determined by ¹H low-field NMR analyses agreed well with those obtained by BSW, indicating the low-field NMR methods as a useful tool for following the effects of plasma treatments on heavy oils, allowing the separation of the effects caused on the water and oil fractions.     

29Si固体核磁共振技术在水泥基材料定量分析中的应用

29 Si固体核磁共振技术是目前研究水泥基材料定量分析的有效工具之一,在水泥化学领域应用广泛.从现代分析测试技术入手,突出了29 Si固体核磁共振技术在水泥化学中的优势,并结合29 Si固体核磁共振定量分析技术和数据,从硅酸盐水泥熟料矿物组分、硅酸盐水泥水化过程量化表征及硅灰掺入的其他水泥基材料的定量分析等方面综述了29 Si固体核磁共振技术在水泥基材料定量分析中的应用,总结了29 Si固体核磁共振技术在水泥基材料领域定量分析存在的问题并展望了核磁共振技术在水泥基材料领域的发展趋势.     

15N relaxation NMR studies of prolyl oligopeptidase, an 80 kDa enzyme, reveal a pre-existing equilibrium between different conformational states

Open and closed: The characterization of protein mobility is crucial for the understanding of biological functions. We have applied NMR spectroscopy to study the conformational dynamics of the 80 kDa enzyme prolyl oligopeptidase (POP). Our results revealed that POP is highly dynamic and that inhibition of catalytic activity shifts this conformational equilibrium towards a less dynamic state.     

Br⊘nsted Acid Sites in Zeolites Characterized by Multinuclear Solid-State NMR Spectroscopy

Nearly all atoms contributing to the local structure of Br?nsted acid sites in zeolites exhibit isotopes accessible for multinuclear solid-state nuclear magnetic resonance (NMR) investigations. Therefore, in the last 15 years, NMR spectroscopy has found numerous applications for the determination of the types of hydroxyl proton in zeolites, of their concentration, accessibility, and mobility, and for the characterization of their acid strength and local structure. It allows the study of the role of hydroxyl groups in the formation of adsorbate complexes and in heterogeneously catalyzed reactions. Meanwhile, NMR spectroscopy belongs to the most powerful techniques for the characterization of Br?nsted acid sites in zeolites and related materials. The basis of this success is the invention of new sample preparation techniques, external magnetic fields with high-flux densities, effective line-narrowing methods, and new two-dimensional experiments, making the detection of highly resolved solid-state NMR spectra and the separation of spectral parameters possible. This article gives a review of these techniques and a summary of the most important applications of multinuclear solid-state NMR spectroscopy for the characterization of Br?nsted acid sites in dehydrated zeolites.     

固体核磁共振在膦酸基质子交换膜中的应用

综述了固体核磁共振(NMR)技术的特点及其在燃料电池用膦酸基质子交换膜分析研究中的应用,重点介绍了运用¹H、³¹P、²⁹Si固体NMR以及¹H、³¹P变温固体NMR技术表征膦酸基质子交换膜的化学结构、氢键网络和质子传导机理等方面的研究进展。该综述表明固体NMR技术是一种研究膦酸基质子交换膜中氢键网络以及局部质子移动性的有效手段,并能进一步探索其质子传导的机理,为固体NMR技术在其他类型质子交换膜研究中的应用给予借鉴,为质子交换膜结构的表征提供一种新的方法。     

Solution‐NMR Characterization of Outer‐Membrane Protein A from E. coli in Lipid Bilayer Nanodiscs and Detergent Micelles

X‐ray crystallography and solution NMR of detergent‐reconstituted OmpA (outer membrane protein A from E. coli) had shown that this protein forms an eight‐stranded transmembrane β‐barrel, but only limited information was obtained for the extracellular loops. In NMR studies of OmpA in two different detergent micelles, “NMR‐invisible” amino acid residues in‐between the extracellular loops and the β‐barrel prevented complete structural characterization. Here, we show that this NMR‐invisible ring around the β‐barrel of OmpA is also present in lipid bilayer nanodiscs and in mixed micelles with a third detergent, thus suggesting that the implicated rate processes have a functional role rather than representing an artifact of the protein reconstitution. In addition to sequence‐specific NMR assignments for OmpA in the nanodiscs, the present results are based on a protocol of micro‐coil TROSY‐ and CRINEPT‐type NMR diffusion measurements for studying the hydrodynamic properties and the foldedness of [²H,¹⁵N]‐labeled membrane proteins in nanodiscs. This protocol can be applied under conditions closely similar to those used for NMR structure determinations or crystallization trials.