咪唑啉季铵盐缓蚀剂的复配机理

通过电化学测试确定咪唑啉季铵盐(IM)和辛基酚聚氧乙烯醚(OP)两种缓蚀剂的最佳复配比,利用X射线光电子能谱(XPS)分析高温高压CO_2腐蚀条件下缓蚀剂在L245钢表面的吸附特性,结合分子动力学计算研究了复配缓蚀剂的缓蚀机理。结果表明:复配后IM缓蚀剂分子在金属表面吸附量增加,同时OP分子的吸附提高了IM缓蚀剂分子在金属表面的吸附覆盖程度,形成致密的保护膜,阻碍溶液中腐蚀性介质对金属表面的侵蚀,有效保护基体减缓腐蚀,从而使得IM和OP复配后的缓蚀率明显升高;IM与OP复配后缓蚀剂分子在Fe(001)表面的吸附强度增大,说明缓蚀剂分子的缓蚀性能本质上是由缓蚀剂分子与金属表面的电子转移行为所决定的。     

Haloform plasma modification of polyolefin surfaces

Polyolefin surfaces (polyethylene and polypropylene) were exposed to haloform (CHX₃) plasmas for introduction of monosort halogen groups. Bromoform and chloroform plasmas produced selectively C-Br (100 Br/100 C) and C-Cl (200 Cl/100 C) groups in high yields. The bromoform plasma showed 1-3 and the chloroform plasma 2-7 post-plasma introduced O-functionalities per 100 C. The polyolefin C-Br groups were grafted wet-chemically or by exposure to the vapour of amines, diols and glycols. Thus, spacer molecules could be covalently bonded to maximal 15 spacer molecules per 100 C for the smallest grafted molecules and 1.2 molecules/100 C for larger molecules as octaaminophenylene-POSS. After metal evaporation the end groups of these polymer-bonded spacer molecules formed also covalent bonds to the metal. Thus, flexible, hydrophobic and barrier elements were introduced into the polymer-metal interfaces for high-impact, high-durable and water-resistant metal-polymer composites as measured by means of peel strengths.     

Influence of the structures of hydrogen-bonded dimeric molecules on their adsorption at graphitized thermal carbon

This study is devoted to the influence of the structures of hydrogen-bonded dimeric molecules on their adsorption at graphitized thermal carbon (GTC). The thermodynamic adsorption characteristics (TACs) of amino acid dimers and dimers of amino acids with acetic acid and formamide at GTC were determined. The results obtained for the adsorption of dimeric molecules at the carbon sorbent were compared with the calculated data for the molecules of the corresponding amino acids at GTC. The geometric parameters of dimeric molecules were varied to analyze the influence of the hydrogen bond lengths on the TACs of the compounds under study.     

A Correlation between the Nature of a Metal and the Adsorption of Surface Active Substances from Aqueous Solutions

A technique for calculating standard Gibbs adsorption energies of organic molecules on various metals is proposed. For using the technique in practice, one needs only the parameters of molecules adsorbed on the same metal. The technique is shown to be applicable to estimating the Gibbs adsorption energies on metals with a relatively low hydrophilicity. A model for the surface layer of chemisorbed water molecules and adsorbed molecules of surface active substances (SAS) on uncharged iron is proposed. The available experimental data on the adsorption of SAS on iron can be explained in terms of the model.     

Radiotracer Study of Addition Agent Behaviour: 8–Benzene Ring Incorporation from Coumarin and Melilotic Acid in Nickel Plating

Melilotic acid molecules are incorporated whole in a nickel electrodeposit. Over a wide range of conditions, however, the benzene ring is incorporated from only 10 to 25% of the coumarin molecules that yield their C3 atom (from the lactone ring) to the deposit, the percentage varying principally with current density. The benzene rings that are found in the deposit probably form part of intact coumarin molecules.

This difference in the incorporation of whole molecules does not fully account for the greater embrittling effect of melilotic acid. It is concluded that the molecules of this substance, adsorbed via the benzene ring, produce a greater disturbance in the growth and structure of the nickel lattice than those of coumarin, adsorbed via the carbon-to-carbon double bond in the lactone ring.     

Permeation von Wasser und anderen kleinen Molekülen durch Polymere

Permeation of water and other small molecules through polymers Corrosion at the interface of a metal and a polymer coating requires transport of water and oxygen through the coating. Permeation of small molecules is determined by their solubility S and their diffusion coefficient D. Whereas at low contents of the dissolved molecules in the rubbery state S and D do not depend on concentration c, they do so strongly in the glassy state. In this case S decreases with increasing c whereas D increases such that the product, i.e. the permeability D − S, remains constant. In the present study a model will be presented which explains these experimental findings. Water molecules are an exception as a solute/solute interaction of the dipolar molecules plays already a strong role at low concentrations.     

有机小分子在修饰铂电极上的电化学氧化

为了改善铂基催化剂氧化有机小分子的活性,制备了硅钨酸修饰铂电极,并利用循环伏安曲线评价其对有机小分子氧化的电催化活性。结果表明:硅钨酸修饰铂电极可以提高铂基电极氧化有机小分子的催化活性。     

DFT modeling of the adsorption of benzene,methanol, and ethanol molecules in activated carbon nanopores

Changes in energetic and structural characteristics of benzene, methanol, and ethanol molecules at their adsorption in nanosize slit-like pores of active carbon are estimated in quantum chemical calculations in the density functional approximation. The most energetically favorable arrangement of benzene molecules is found to be that when the molecular planes are parallel to each other and to the nanopore walls. Alcohol molecules are predominantly arranged so that C-O and C-C bonds are nearly parallel to the nanopore walls, while O-H bond is directed toward the nearest wall. At the adsorption of two alcohol molecules, they form a hydrogen bond and their skeletons are also parallel to the nanopore wall.     

On the origin of multilevel conductance and memory in ultrathin organic films

Conductivity of certain organic molecules switch to a high-state via electroreduction. Different high-states or multilevel conductivity in organics has been due to different density of high-conducting molecules in a device. We have studied how the population distribution of reduced molecules changes in achieving different conductivity levels. In devices based on a few molecular layers, we have observed that the number of conductivity levels can exceed the number of Langmuir–Blodgett layers. The results showed that the distribution of high-conducting molecules did not increase layer-by-layer, but throughout the volume of the device enabling large number of conductivity levels for higher level (multibit) applications.     

Study of the sorption-kinetic properties of carbon molecular sieves

To elucidate the role of the electron-exchange properties of arene molecules that form the pore walls of carbon molecular sieves in their interactions with sorbate molecules, the correlation between the electronexchange and sorption-kinetic properties was studied. The electron-exchange properties were estimated by using quantum-chemical modeling based on the energies of formation of singly charged anions and cations and neutral (both oxidized and reduced) molecules.     

Molecular rectifiers and transistors based on π-conjugated materials

Concepts and experimental results related to molecular rectifiers and transistors are reviewed. ‘Devices’ based on donor-δ bridge-acceptor molecules, conjugated zwitterionic molecules, macrocyclic molecules, metal clusters, fullerenes and carbon nanotubes are discussed. Current-voltage characteristics showing rectifier properties are presented, as well as experiments in which the current-voltage characteristics are modulated by a gate voltage (transistor effect).     

A correlation between Malva sylvestris extracts molecules and their corrosion inhibition capabilities

Experimental and quantum chemical investigations have been coupled in order to determine anticorrosion potential of Malva sylvestris extract molecules. The plant extract is a mixture of chemicals of which only four are abundant. Two groups of molecules are evidenced using quantum chemical parameters. The electrochemical investigation has classified the plant extract as a mixed-type inhibitor. The %EI has been only 54.5% due to antagonistic effects of the extract molecules.     

CO在Pt-Fe催化剂的Pt/Fe/Pt(111)表面的吸附研究

低温(110~130 K)下,将次表层Fe结构的Pt-Fe模型催化剂(即Pt/Fe/Pt(111)结构)暴露于不同量CO气体,经不同温度退火后,采用高分辨电子能量损失谱(HREELS)研究催化剂表面CO分子的振动谱。结果表明,当CO的暴露量低于0.2 L (Langmuir)时,Pt/Fe/Pt(111)表面只存在顶位吸附;当暴露量大于0.4 L,除了顶位吸附外,桥位吸附开始出现;顶位吸附分子的C-O键振动峰随着暴露量的增加不断向高波数方向偏移。退火温度影响Pt/Fe/Pt(111)表面CO的吸附形式,低于255 K时,顶位吸附分子的脱附速率大于桥位吸附分子;高于255 K时,桥位吸附分子的脱附速率较大,并先于顶位吸附的CO从表面完全脱附,其完全脱附温度比Pt(111)表面低50 K。     

Understanding the effect of surfactant aggregation on corrosion inhibition of mild steel in acidic medium

Corrosion inhibition by surfactant molecules is related to the surfactant's ability to aggregate at interfaces and in solution. Understanding the factors that affect aggregation as well as the state of aggregation of surfactant molecules on metal surfaces is, therefore, an important prerequisite to understanding corrosion inhibition by surfactant molecules. This article investigates the relationship between surfactant aggregation and mild steel corrosion inhibition in acidic medium using cetyl pyridinium chloride and cety trimethyl ammonium bromide.     

Synthesis of solution processable ultraviolet sensitive organic molecules and their application in hybrid UV photodetector

Two new solution processable organic molecules based on carbazole and triphenylamine (TPA) substituted fluorene were synthesized by Suzuki coupling reaction. The bandgap of the molecules can be controlled by the 3,6-linkage of the carbazole. The propeller-shaped TPA moieties endow the molecules with good thermal stability and perfect solution processability. Smooth films of both molecules could be readily obtained by spin-coating and n-type ZnO nanoparticles were further incorporated to construct bulk-heterojunction. Under the excitation of 1 mW/cm² ultraviolet light at 365 nm, devices with those hybrid films as active layers show a relative quick response with photo-to-dark current ratio of about three orders of magnitude. The current decay time (decay to 1% of the value before removing of the light) is less than 200 ms. Moreover, the spectral response of the devices covers 300–400 nm and can be well tuned by the conjugation length of the organic molecules. Those results indicate that the synthesized molecules might be candidates for solution processable low cost UV photodetectors.     

Star-shaped dendritic molecules based on carboxylated carbazole and pyrrole as peripheral oxidizable units

The synthesis and spectroscopic characterization of three tricarboxylated pyrrole (Pyr)- and carbazole (Cbz)-containing star-shaped dendritic molecules 1–3 have been described here. Clauson–Kaas, amide coupling and debenzylation reactions have been used as key chemical tools. Electropolymerization of these oxidizable molecules has been investigated. The carboxylated Cbz-based molecules upon oxidative electropolymerization produced stable electroactive polyCOOH polyCbz films.     

Dynamics of charge transfer in molecular switches

With impurity molecules working as switches, the charge transfer on a single conducting polymer chain is studied. The chain is modeled by a modified tight-binding Hamiltonian extended to include the effects of an external field and the parameters of the switching molecules. The charge transfer through the sites that work like a switch is analyzed by the numerical integration of the equations of motion. Two basic types of molecular switches are studied: single and pairs of donor—acceptor molecules bonded to the chain. The main differences between these two models of switches are determined. We have found that the single radical switch has an anisotropic character and only works for solitons with the same parity of bonding site. For the donor—acceptor pair we have encountered that the chain offers a wider range of devices, from simple switches to perfect molecular rectifiers. The influence of the parameters of the molecules on the charge transfer and the changes they must undergo to characterize the molecular switch are obtained. The role of the length of separation between the sites where the donor and acceptor molecules bond is clarified. The optimum switch configuration is determined.     

Boomerang-shaped octupolar molecules derived from triphenylbenzene

Octupolar molecules are of particular interest in the field of non-linear optics due to their potentially large quadratic non-linearities and challenging material engineering possibilities. In order to design molecules combining enhanced first hyperpolarizabilities β and excellent transparency in the visible region, we have implemented a strategy based on the design of all-organic molecules showing multi-dimensional intramolecular charge transfer. In this perspective, we have designed original propeller-shaped conjugated molecules based on a central triphenylbenzene core bearing three phenylene–vinylene blades. By grafting either electron-donating or electron-withdrawing terminal moieties and taking advantage of multidirectional charge transfer between the centre and the periphery of these molecules, octupolar compounds displaying excellent transparency in the visible region and larger non-linearity than DR1 were obtained (up to β(0)=140×10⁻³⁰ esu with λ_max=385 nm).     

Liquid crystals ‘made of gold’

The simple linear coordination of gold(I) helps in the understanding of structure-property relationships in liquid crystals based on metal-containing molecules. This simple geometry also allows the preparation of materials showing a range of mesophases, based on both rod-like and disc-like molecules.     

Effect of ether coordination for sodium intercalation into poly(vinyl chloride) cokes with different graphitization degree

Sodium intercalation in three unidentate and three bidentate ether solutions having different molecular sizes was investigated using poly(vinyl chloride) cokes heat-treated at different temperatures. Co-intercalation of ether molecules with sodium cations was found to be governed strongly by the graphitization degree of hosts in contrast with other alkali metals. This tendency is dependent on the strength of bond between sodium and ether molecule, and also the bulk of coordinated molecules; the limit of graphitization degree for co-intercalation of solvent molecules was lower in bidentate solution than in unidentate ones, and the large solvents were prevented from co-intercalation more strongly than small ones.