共查询到20条相似文献,搜索用时 171 毫秒
1.
Zakaria Salmi Sarra Gam-Derouich Samia Mahouche-Chergui Mireille Turmine Mohamed M. Chehimi 《Chemical Papers》2012,66(5):369-391
This review emphasises the role of aryl diazonium compounds as a new class of coupling agents for grafting polymer thin layers
onto carbon, diamond, metals, metal oxides, alloys, semi-conductors, ceramics, and polymers. Physical and chemical methods
are first reported for anchoring aryl layers to the surfaces, then the review concentrates on the modification of the above
substrates by thin polymer films via a range of the “grafting from” and “grafting onto” strategies. Some applications are
described which highlight the important role that diazonium salts will continue to play in the near future in the polymer
and surface sciences. 相似文献
2.
Kapila V Almanza-Workman AM Deymier PA Raghavan S 《The Journal of chemical physics》2004,120(19):9277-9285
Aqueous chemistries have recently been shown to be useful for the deposition of hydrophobic films of nonionic and cationic silanes on hydrophilic substrates for the prevention of stiction in MEMS. The Monte Carlo method is used to simulate in two dimensions the self-assembly of silane films on a hydrophilic surface. We investigate the impact of charged group in cationic silane on the overall structure of the films. We characterize the film structure with spatial pair correlations at each molecular layer of the deposited films. The simulations reveal long-range correlations for the film of cationic silanes. Based on our two-dimensional simulations, we report an average "most probable" structure for the films of nonionic and cationic silanes. 相似文献
3.
钼酸盐封闭后处理的热镀锌钢板硅烷膜的耐蚀性 总被引:2,自引:0,他引:2
为进一步增强硅烷膜的耐蚀性, 将硅烷化热镀锌钢板用钼酸盐溶液进行封闭后处理, 并采用扫描电子显微镜(SEM)、中性盐雾(NSS)实验、盐水全浸实验和电化学技术研究了所得复合膜层的表面形貌和耐蚀性能. 结果表明: 经钼酸盐溶液封闭处理后, 硅烷膜的孔隙被填充, 在锌层表面形成了由硅烷膜和钼酸盐转化膜构成的连续完整致密的复合膜; 复合膜的耐蚀性能明显提高, 且与钼酸盐溶液的封闭时间有关, 封闭60 s时所形成的复合膜的耐蚀性最佳. 在5%(w, 质量分数)NaCl溶液中的电化学测量结果表明: 硅烷化热镀锌钢板经钼酸盐溶液封闭处理后, 同时抑制了腐蚀过程中的阳极和阴极反应, 但主要是抑制阴极反应, 导致腐蚀电流密度明显减小, 发挥了单一硅烷膜和单一钼酸盐转化膜腐蚀防护的协同效应, 腐蚀防护效率高达99.1%; 随浸泡时间延长, 试样低频扩散阻抗先增大后减小, 表明膜层具有一定的“自愈”能力, 其耐蚀性优于常规铬酸盐钝化膜. 相似文献
4.
5.
Inorganic–organic hybrid coatings by sol–gel process are very suitable for fighting corrosion. Inorganic sols in hybrid coatings
not only increase adhesion by forming chemical bonds between metals and hybrid coatings, but also improve comprehensive performances
of polymer in the coatings. Different organic polymers or organic functionalities are introduced into gel network to achieve
tailored properties, such as hydrophobic properties, increasing cross-linking density, etc. As for corrosion protection of
metals organic components of hybrid coatings are selected to repel water and form dense thick films and reduce coating porosity.
The factors, such as the ratio of inorganic and organic components, cure temperature, pigments in hybrid coatings, need to
be optimized for attaining hybrid films with the maximum corrosion resistance. Electro-deposition technique offers relatively
thick homogeneous defect-free hybrid coatings in comparison to dip or spin coating techniques. Green cerium ions and non-ionizable
organic inhibitors are more developed in hybrid coatings nowadays than other corrosion inhibitors. Long-term corrosion resistance
techniques of inhibitors are discussed. The inhibitors entrapped in the nanocontainers are doped in hybrid films to prolong
release of the inhibitors to damaged zones, which is discussed in detail. Among all the nanocontainers of corrosion inhibitors
the prospective techniques which show superior corrosion protection are cyclodextrin/organic inhibitor inclusion complexes
and layer by layer assembly of organic corrosion inhibitors in nanocontainers. Super-hydrophobic property of hybrid coatings
derives from low surface tension and surface roughness of hybrid coatings, which endues the films with excellent corrosion
protection for metals, but the durable property of super-hydrophobic coatings needs to be improved for industrial application.
An ideal multiple model of hybrid coatings for superior anti-corrosion of metals proposed is a combination of super-hydrophobic
hybrid coatings and underlying hybrid coatings doped with sustained release of corrosion inhibitors on metal substrates. 相似文献
6.
Multivariate statistical assessment of polluted soils 总被引:9,自引:0,他引:9
Vasil Simeonov Juergen Einax Stafan Tsakovski Joerg Kraft 《Central European Journal of Chemistry》2005,3(1):1-9
This study deals with the application of several multivariate statistical methods (cluster analysis, principal components
analysis, multiple regression on absolute principal components scores) for assessment of soil pollution by heavy metals. The
sampling was performed in a heavily polluted region and the chemometric analysis revealed four latent factors, which describe
84.5 % of the total variance of the system, responsible for the data structure. These factors, whose identity was proved also
by cluster analysis, were conditionally named “ore specific”, “metal industrial”, “cement industrial”, and “steel production”
factors. Further, the contribution of each identified factor to the total pollution of the soil by each metal pollutant in
consideration was determined. 相似文献
7.
Summary Mixed-ligand or “mixed-interaction” stationary phases are composed of bonded silanes possessing both ionic and hydrophobic
character. The complex retention properties exhibited by these phases have been particularly useful in separating large biomolecules,
such as synthetic single-stranded oligodeoxyribonucleotides. By isolating the individual properties of separate ligands present
in mixed-ligand stationary phases a better understanding of the heterogeneous surface was sought. Specifically a dilute anion-exchange
mixed-ligand phase of 5% surface coverage showed dramatically different selectivity for oligomers compared to hydrophobic
stationary phases. Of particular interest was the increased selectivity observed in separating oligonucleotides differing
on the 3′ end over conventional reversed-phases supports. 相似文献
8.
Yu. I. Kuznetsov D. B. Vershok S. F. Timashev A. B. Solov’eva P. I. Misurkin V. A. Timofeeva S. G. Lakeev 《Russian Journal of Electrochemistry》2010,46(10):1155-1166
The process of anticorrosion magnetite coating (MC) formation on low-carbon steel is studied in alkali-free nitrate converting
media at the temperatures of 70–98°C reduced as compared to those used (130–145°C) in standard technologies of steel bluing:
formation of such coatings in alkaline nitrate solutions. Alongside with the conventional corrosion-electrochemical methods
of analysis of the formed MCs, the regularities of the MC surface reliefs were studied using the method of atomic force microscopy
combined with the technique of flicker-noise spectroscopy (FNS) for processing digitized images and obtaining the parameters
of the MC surface structure in different nanometer ranges. It was shown that it is necessary to introduce additives of metal
nitrates with a low cation radius into the ammonium nitrate converting solution to obtain MCs with a high corrosion stability
at the first stage of MC formation and the final stage must consist in the further “passivation” of MCs: MC treatment by aqueous
solutions based on nontoxic carboxylates. According to the FNS analysis of the surface structure of the formed MCs, a significant
decrease of the FNS “point” factor, an indicator of MC corrosion instability, occurred during the final treatment. On this
basis, one could characterize quantitatively the results of accelerated corrosion tests: no steel corrosion occurred on the
thus formed coatings for 42 days under standard severe conditions: 100% relative humidity and daily “showering”. The performed
study reveals fundamental possibilities for solving the problems of standardization of the anticorrosion coating surface based
on the analysis of their surface profile in the nanometer range. 相似文献
9.
O. V. Borshchev S. A. Ponomarenko E. A. Kleymyuk Yu. N. Luponosov N. M. Surin A. M. Muzafarov 《Russian Chemical Bulletin》2010,59(4):797-805
The synthesis of new dendrimers and branched oligothiophene silanes containing bithiophene groups at the periphery and quaterthiophene
fragments at the center of the molecule is described. Specific features of bithiophene silane bromination were shown, and
the conditions for the efficient synthesis of methyltris(5-bromo-2,2′-bithiophen-5-yl)silane have been found for the first
time. The optical properties of the synthesized compounds were studied. The efficiency of the electron excitation energy transfer
between the fragments of branched bi-and quaterthiophene silanes was measured. 相似文献
10.
Development, recent historical background and analytical applications of promising sensor instruments based on sensor arrays
with data processing by pattern recognition methods have been described. Attention is paid to the “electronic tongue” based
on an array of original non-specific (non-selective) potentiometric chemical sensors. Application results for integral qualitative
analysis of beverages and for quantitative analysis of biological liquids and solutions, containing heavy metals are reported.
Discriminating abilities and precision obtained allow to consider “electronic tongue” as a perspective analytical tool.
Received: 17 July 1997 / Revised: 19 February 1998 / Accepted: 24 February 1998 相似文献
11.
A. D. Bulanov P. G. Sennikov A. Yu. Sozin A. Yu. Lashkov O. Yu. Troshin 《Russian Journal of Inorganic Chemistry》2011,56(4):510-512
The possibility of the reduction of hexafluorodisiloxane by calcium hydride in the synthesis of silane from silicon tetrafluoride
has been studied. This reaction is shown to be not decisive for oxygen contamination of silane. The most likely reason for
the appearance of impurity Si2OH6 in “fluoride” silane is the Ca(OH)2-catalyzed reaction of silane with trace water. The concentration of impurity Si2OH6 in silane at the stage of synthesis may be efficiently decreased by the preliminary purging of calcium hydride with a hydrogen
(grade A) flow. 相似文献
12.
D. V. Vlasov L. A. Apresyan T. V. Vlasova V. I. Kryshtob 《Polymer Science Series A》2011,53(5):430-436
The anomalous behavior of the electrical conductivity of transparent poly(vinyl chloride) films is experimentally studied
at field voltages approaching the breakdown threshold, above the threshold, and far below the threshold. The effects of strong
nonlinearity, relaxation drifts, and spontaneous reversible transitions between states with high and low electrical conductivities
are revealed for the first time in “thick” (20–100 μm) plasticized transparent poly(vinyl chloride) films. When a certain
threshold is exceeded, relaxation oscillations in the test sample are generated and their frequency is proportional to the
applied voltage. During a “mild” breakdown, the polymer film passes into the high-conductivity state (the current increases
by four or more orders of magnitude), which is identical to the states observed during low-voltage transitions. A simple qualitative
model explaining the anomalous character of the electrical conductivity of plasticized poly(vinyl chloride) films is advanced. 相似文献
13.
Yi Zhang Junkang Hao Changjie Zhou Kai Chang 《Journal of mathematical chemistry》2009,46(4):1203-1212
In this article, we propose a new method to measure DNA similarity based on a normalized Lempel-Ziv complexity scheme. The
new method can weaken the effect of sequence length on complexity measurement and save computation time. Firstly, a DNA sequence
is transformed into three (0,1)-sequences based on a scheme, which considers “A” and “non-A” , “G” and “non-G”, “C” and “non-C”
bases respectively. Then, the normalized Lempel-Ziv complexity of the three (0,1)-sequences constitute a 3D vector. Finally,
by the 3D vector, one may characterize DNA sequences and compute similarity matrix for them. The examination of similarities
of two sets of DNA sequences illustrates the utility of the method in local and global similarity analysis. 相似文献
14.
Petr Kluson Stepan Kment Magdalena Morozova Pavel Dytrych Stanislav Hejda Morwenna Slater Zdenek Hubicka Josef Krysa 《Chemical Papers》2012,66(5):446-460
Chemistry and physics of thin semiconducting layers of various types are subjects of intense research. Especially when nanotechnology
methods such as self-assembly are involved, amazing structural and/or functional properties may appear. Also modern physical
methods using variously organized plasma arrangements are able to produce uniform structures with distinctive functionality.
In this review, based virtually on our own work, discussions on the preparation, structure, morphology, and function of titanium(IV)
oxide nanoscopic thin films are presented. It was shown that structurally and functionally similar titanium(IV) oxide films
can be prepared via completely different preparation techniques. Function tests were arranged as “primary”, covering the assessment
of the light induced charge separation efficiency, and “secondary”, based on photocatalytic surface oxidations. 相似文献
15.
Multivariate analysis of HT/GC-(IT)MS chromatographic profiles of triacylglycerol for classification of olive oil varieties 总被引:1,自引:0,他引:1
Cristina Ruiz-Samblás Luis Cuadros-Rodríguez Antonio González-Casado Francisco de Paula Rodríguez García Paulina de la Mata-Espinosa Juan Manuel Bosque-Sendra 《Analytical and bioanalytical chemistry》2011,399(6):2093-2103
The ability of multivariate analysis methods such as hierarchical cluster analysis, principal component analysis and partial
least squares-discriminant analysis (PLS-DA) to achieve olive oil classification based on the olive fruit varieties from their
triacylglycerols profile, have been investigated. The variations in the raw chromatographic data sets of 56 olive oil samples
were studied by high-temperature gas chromatography with (ion trap) mass spectrometry detection. The olive oil samples were
of four different categories (“extra-virgin olive oil”, “virgin olive oil”, “olive oil” and “olive-pomace” oil), and for the
“extra-virgin” category, six different well-identified olive oil varieties (“hojiblanca”, “manzanilla”, “picual”, “cornicabra”,
“arbequina” and “frantoio”) and some blends of unidentified varieties. Moreover, by pre-processing methods of chemometric
(to linearise the response of the variables) such as peak-shifting, baseline (weighted least squares) and mean centering,
it was possible to improve the model and grouping between different varieties of olive oils. By using the first three principal
components, it was possible to account for 79.50% of the information on the original data. The fitted PLS-DA model succeeded
in classifying the samples. Correct classification rates were assessed by cross-validation. 相似文献
16.
Ludmila C. Fidale Constance Ißbrücker Priscilla L. Silva Camila M. Lucheti Thomas Heinze Omar A. El Seoud 《Cellulose (London, England)》2010,17(5):937-951
Although cellulose acetates, CAs, are extensively employed there is scant information about the systematic dependence of their properties on their degree of substitution, DS; this is the subject of the present work. Nine CAs samples, DS from
0.83 to 3.0 were synthesized; their films were prepared. The following solvatochromic probes have been employed in order to
determine the empirical polarity, E
T(33); “acidity, α”; “basicity, β”, and “dipolarity/polarizability, π*” of the casted films: 2,6-dichloro-4-(2,4,6-triphenyl-pyridinium-1-yl)
phenolate, WB; 4-nitroaniline; 4-nitroanisole; 4-nitro-N,N-dimethylaniline; 2,6-diphenyl-4-(2,4,6-triphenyl-pyridinium-1-yl)phenolate, RB. Additionally, two systems, ethanol plus ethyl
acetate (EtOH–EtAc), and cellulose plus cellulose triacetate, CTA, were employed as models for CAs of different DS. Regarding
the model systems, the following was observed: (i) For EtOH–EtAc, the dependence of all solvatochromic parameters on the “equivalent-DS”
of the binary mixture was non-linear because of preferential solvation; (ii) The dependence of E
T(33) on equivalent DS of the cellulose–CTA films is linear, but the slope is smaller than that of the corresponding plot for
CAs. This is attributed to the more efficient hydrogen bonding in the model system, a conclusion corroborated by IR measurements.
The dependence of solvatochromic parameters of CAs on their DS is described by the simple equations; a consequence of the
substitution of the OH by the ester group. The thermal properties of bulk CAs samples were investigated by DSC and TGA; their
dependence on DS is described by simple equations. The relevance of these data to the processing and applications of CAs is
briefly discussed. 相似文献
17.
N. A. Malakhova A. A. Mysik S. Yu. Saraeva N. Yu. Stozhko M. A. Uimin A. E. Ermakov Kh. Z. Brainina 《Journal of Analytical Chemistry》2010,65(6):640-647
A procedure is developed for the immobilization of bismuth nanoparticles prepared by the method of gas condensation on inert
supports manufactured by the screen printing method using carbon-containing inks. The electrochemical behavior of the immobilized
bismuth nanoparticles is investigated, and the conditions of their electrochemical activation are found. The composition of
the modifying suspension “bismuth nanoparticles-liquid” is optimized. The elaborated thick-film carbon-containing electrode
modified by bismuth nanoparticles is shown to be similar in its analytical parameters to the commercially available thick-film
carbon-containing electrode premodified by calomel, and substantially exceeds carbon-containing electrodes with electrolytically
deposited bismuth films in its properties. The limits of detection for heavy metals by stripping voltammetry are as follows
(μg/L): 0.38 for Zn(II), 0.40 for Cd(II), and 0.55 for Pb(II) at the preconcentration time 180 s. 相似文献
18.
Liquid crystalline(LC) polymers with a shish-kebab-type moiety on their cross-conjugated(p-phenylene)s-poly(p-phenylenevinylene) s main chains were synthesized through Gilch polymerization in order to develop a kind of polymers available for linearly polarized white-light-emitting from single chain.In this system,the 2,5-bis(4’-alkoxyphenyl)benzene as the "kebabs" connects with poly(p-phenylenevinylene)(PPV) main chain backbone using its molecular gravity center and the PPV as the "shish" or "skewer"(the "shish-kebab").The polymers possess desirable properties such as excellent solubility and liquid crystalline properties.To drop the "kebabs" of the 2,5-bis(4’-alkoxyphenyl)benzene into the orientation microgroove of aligned polyimide film,not only the "shish" of polymer main chain can be aligned by the virtue of orientation of "kebabs" but also the uniform cross-conjugated structure between the "kebabs" and "shish" can be broken. Then,the alignment of the polymer main chain showed yellow light emission and was also accompanied by orientation of the LC side chains showing blue light emission,this gave rise to a notable linearly polarized white fluorescence. 相似文献
19.
The current development and future prospects of nanotechnology are discussed with special emphasis on the pros and cons of the “bottom-up” and “top-down” approaches to nanotechnology, and the eventual merging of the two, at the scale of about 30 nm in feature size, to form a new “hybrid” technology. At the scale of about 3 nm in feature size, this “hybrid” technology will be challenged by the emerging “supramolecular” and “molecular” technologies epitomized by large-scale integration of single-molecule devices. Ultimately the “supramolecular” and “molecular” technologies will yield to “atomic” or “nuclear” technologies at the dimension of below 0.3 nm whereby single-atom, single-electron, single-spin, single-photon devices become realities. 相似文献
20.
新型十二烷基三甲氧基硅烷/氧化石墨烯复合膜对430不锈钢耐蚀性能的影响 总被引:1,自引:0,他引:1
使用一步电沉积法在430不锈钢上制备出十二烷基三甲氧基硅烷(DTES)/氧化石墨烯(GO)复合膜。 拉曼光谱(Raman)与扫描电子显微镜(SEM)测试表明,氧化石墨烯均匀地混合在硅烷膜中,并用电化学交流阻抗与极化曲线方法对这种复合膜所保护的430不锈钢进行耐蚀性能测试。 结果显示,在3.5%NaCl溶液中,430不锈钢会发生腐蚀反应,而存在硅烷复合膜的430不锈钢的耐蚀性能显著地提高。 研究表明,由于氧化石墨烯出色的阻隔性能一定程度上弥补了硅烷膜的缺陷,而且延长了腐蚀介质通过硅烷基质的路径,因此复合膜有着对基底物质更强的保护性能。 相似文献