共查询到20条相似文献,搜索用时 31 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.
Volker Warzelhan 《先进技术聚合物》1997,8(4):210-214
Plastics production has grown rapidly in the past 30 years. The versatility of plastics which is not exceeded by any other class of materials, guarantees that polymers will continue to be very important in the future. However, at present a distinct change is taking place in polymer research and development. While in the pioneering days of plastics new polymer properties were determined by the choice of suitable monomers, today the commercialization of polymers from new monomers is restricted to a few specialities with a rather modest production volume. On the other hand, the number of new polymers derived from old monomers is increasing very rapidly. The development of highly selective catalysts and advances in reactor technology have provided the means for producing new tailor-made polymers. The same is true regarding new polymer blends and alloys based on old polymers: blending immiscible polymers yields materials with property profiles superior to the features of the individual components. Using selected examples, this paper will discuss trends, possibilities and challenges for structural polymer research in industry. © 1997 John Wiley & Sons, Ltd. 相似文献
3.
Hans-Henning Kausch-Blecken von Schmeling 《Colloid and polymer science》2011,289(13):1407-1427
A definition of macromolecular science (as opposed to polymer science and engineering) is given, from which the year 1930 is derived as the year of its birth. The scope of treatment of this paper will be limited
to solid technical polymers. Some important discoveries of polymer technology in the nineteenth century are reviewed together with the reason why the concept of macromolecules and the theory of rubber
elasticity did not emerge earlier. The role of chain backbones in structure formation and mechanical loading of technical
polymers has been heavily discussed ever since and has attracted this author for most of his scientific work. He offers a
personal perspective of the most important achievements in three domains of macromolecular science: the synthesis of well-designed
chain molecules, structural characterization and the understanding of the micro-mechanics of (nano-structured) polymer materials.
Progress is generally documented by citing individual references from the discussed periods—well knowing that the development
of science is due to the contributions of many more people. In conclusion, a critical outlook will be attempted on future
trends in the design and application of well-adapted—and frequently complex—polymer systems towards growing human needs. 相似文献
4.
超临界二氧化碳在聚合物整体接枝改性中的应用 总被引:1,自引:0,他引:1
聚烯烃膜的整体改性是优化其性能并增加附加值的重要途径之一。常用的方法是在溶液中或者熔融状态下均相共混或接枝,但是对于那些既不溶解亦不熔融的聚合物,非均相法将是最佳的选择。而利用超临界二氧化碳可以将反应单体溶胀进入聚合物基体当中进行聚合反应,生成聚合物共混或接枝聚合物。本文综述了近年来超临界二氧化碳在固相聚烯烃整体接枝改... 相似文献
5.
Paolo Galli 《Macromolecular Symposia》1996,112(1):1-16
The discovery (1968) of the high yield Ziegler-Natta catalysts based on active MgCl2 was the beginning of a scientific and industrial revolution that has brought about the creation of superactive, isospecific, spheriform fourth generation catalytic systems. The rationalization of the polymer/catalyst replication phenomenon and the understanding of the catalyst “architecture” effects on polymer shape and morphology has led to the exploitation of the “Reactor Granule Technology”. This has made the generation of a broad range of homo, copolymers and multiphase alloys (Catalloy) possible by synthesis, most of which having a previously unobtainable spectrum of performance (Refs. 1,2,3). The reactor granule technology concept has also been the basis for the achievement of a family of polyolefin/non polyolefin alloys with engineering properties. More recently, the reactor granule approach has been extended so as to couple the advantages of both heterogeneous and homogeneous metallocene catalysts (mixed catalysis), thus allowing the synthesis of a very new family of “in situ” polyolefin alloys. 相似文献
6.
This review highlights the frontier scientific research in the development of polymer nanocomposites for electrical energy storage applications. Considerable progress has been made over the past several years in the enhancement of the energy densities of the polymer nanocomposites via tuning the chemical structures of ceramic fillers and polymer matrix and engineering the polymer–ceramic interfaces. This article summarizes a range of current approaches to dielectric polymer nanocomposites, including the ferroelectric polymer matrix, increase of the dielectric permittivity using high‐permittivity ceramic fillers and conductive dopants, preparation of uniform composite films based on surface‐functionalized fillers, and utilization of the interfacial coupling effect. Primary attentions have been paid to the dielectric properties at different electric fields and their correlation with film morphology, chemical structure, and filler concentration. This article concludes with a discussion of scientific issues that remain to be addressed as well as recommendations for future research. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1421–1429, 2011 相似文献
7.
The milestones of the life and activity of the outstanding Russian inorganic chemist and metallurgist are outlined; three
spheres of his activity are considered: scientific research, educational activity, and science organization. The attention
is focused on the elaboration and development of the physicochemical analysis technique, works dealing with natural salt deposits
and water-salt systems. N.S. Kurnakov’s role in the development of the coordination chemistry is noted. N.S. Kurnakov’s contribution
to education made in Petersburg (Petrograd, Leningrad) and M.V. Lomonosov Moscow State University is demonstrated. N.S. Kurnakov’s
outstanding role in the foundation of new scientific institutions, his science organizational activity in the Academy of sciences
and in the foundation of Russian chemical and metallurgical industries is emphasized. 相似文献
8.
凝胶色谱仪是高分子化学学科日常科研工作的必备仪器.随着高校高分子化学学科的迅猛发展,如何提高该仪器的开放使用和管理维护变得十分重要.总结了管理的经验及体会. 相似文献
9.
10.
A test is proposed for the evaluation of the concentration of osmium in solutions based on the direct proportionality between
the concentrations of osmium(IV) or osmium(VI) and the length of the colored zone on the indicator paper; the latter is covered
by a polymer film and is in contact with the test solution along one edge. The paper is impregnated by 3-methyl-2,6-dimercapto-1,4-thiopyrone,
which reacts with osmium ions in the solid phase and forms poorly soluble products. The effectiveness of the dynamic preconcentration
of osmium(IV) from solutions, obtained upon the reduction of its volatile tetroxide for the subsequent visual test and colorimetric
determination on paper filters in the total concentration range 4–400 μg in samples for a sample volume of 100 mL, is demonstrated.
The procedures developed are utilized for the determination of osmium in ore processing wastes from Dzhezkazgan’s mines and
in its alloys. 相似文献
11.
12.
H. Janeschitz-Kriegl 《Colloid and polymer science》1997,275(12):1121-1135
In view of the enormous difficulties in obtaining reliable experimental data for the purpose of structure simulation with
the aid of computer programs (presently being so popular), every classifying endeavor must be considered of great importance.
One of the goals of such an endeavor is the demarcation of characteristic temperature ranges. With the aid of thermodynamic
considerations an estimate of the restricted temperature range of metastable undercooling, in which the classical theory of
homogeneous nucleation, as developed for polymer solutions, is valid also for polymer melts (“thermal nucleation”) can be
given. This consideration includes a discussion of the course of the relevant interface tensions along the co-existence lines
of the P–T diagram. The so-called spinodal crystallization mode (see [1–3]) is found at lower temperatures and seems to be quite common
in polymer crystallization. In this connection the so-called athermal nucleation can be identified with a specific process.
However, the present author is not in favor of the term “spinodal mode”. This is explained by a comparison with the meaning
of spinodal decomposition into two phases in the ordinary gas–liquid phase transition, which always occurs at the lower bound
of the metastable undercooling. Remarkably, spinodal decomposition cannot be defined in the same way for the liquid–solid
transition. Anyway, the author tries hard to induce unorthodox trains of thought in the hope to revive the discussion of a
difficult matter, which has almost gone to sleep, before a satisfying settlement has been reached.
Received: 3 June 1997 Accepted: 19 August 1997 相似文献
13.
V. P. Shibaev 《Polymer Science Series A》2014,56(6):727-762
In the first part of this review, in a brief historical perspective, we consider the evolution of the scientific activity of Nikolai Al’fredovich Platé, Academician of the Russian Academy of Sciences: from grafted polymer systems to comb-shaped and liquid-crystalline polymers. The main biographical data on Platé are related to his scientific work at Moscow State University, and his research-development strategy to create and study of LC polymers with comb-shaped structure is considered. The second part of the article is devoted to discussion of scientific directions in this area that were developed in the last five years at the Laboratory of Chemical Transformations of Polymers, where Platé started his scientific activity. Special attention is paid to the research data on photochromic liquid-crystal polymers and composites. A concept of the preparation of multifunctional comb-shaped LC polymers containing mesogenic, photochromic, and chiral groups, as well as functional (crown ether) fragments, is presented. The photo-orientational processes occurring in photochromic LC polymers, which were used to prepare “command” surfaces and photo-orientators, are considered in detail. The preparation of a new class of photochromic polyamides with azobenzene, cinnamoyl and coumarin groups, which have been proposed for the obtaining of polymer films with latent data recording, is described. The phase behaviors and photo-optical properties of synthesized photochromic triple LC block copolymers are reported. Examples of holograms based on cholesteric LC blends, which allow double recording on the same polymer film, are presented. The results of investigations of light-controlled cholesteric polymer-stabilized LC networks with crown ether fragments in the compositions of macromolecules that are able to form complexes with metal ions are presented. The methods of preparation of photocontrolled and electrically controlled polymer LC nanocomposites with nanoparticles, as well as research data on their photo-optical properties, are considered. 相似文献
14.
Molten polymer process streams are difficult to analyze either in- or on-line because of sampling problems due to the high temperature and viscosity of the molten state. Real-time monitoring of chemical compositions in these processes can significantly improve safety and product quality and minimize process costs and waste. The information content of the mid-infrared spectrum combined with the recent development of rugged process Fourier transform (FT) IR spectrometers is stimulating the application of process FT-IR to industrial polymer melt processes. Sampling considerations for polymer melts are reviewed. Also, the use of FT-IR spectrometry for on-line measurements of the polymer composition for polymer blends and copolymers in the melt, and the question of how this information could be used to monitor and control the quality of the product given by the process are discussed. 相似文献
15.
Fu-Ming Wang Jyh-Tsung Lee Ju-Hsiang Cheng Chin-Shu Cheng Chang-Rung Yang 《Journal of Solid State Electrochemistry》2009,13(9):1425-1431
Poly (acrylate-co-imide)-based gel polymer electrolytes are synthesized by in situ free radical polymerization. Infrared spectroscopy confirms
the complete polymerization of gel polymer electrolytes. The ionic conductivity of gel polymer electrolytes are measured as
a function of different repeating EO units of polyacrylates. An optimal ionic conductivity of the poly (PEGMEMA1100-BMI) gel polymer electrolyte is determined to be 4.8 × 10–3 S/cm at 25 °C. The lithium transference number is found to be 0.29. The cyclic voltammogram shows that the wide electrochemical
stability window of the gel polymer electrolyte varies from −0.5 to 4.20 V (vs. Li/Li+). Furthermore, we found the transport properties of novel gel polymer electrolytes are dependent on the EO design and are
also related to the rate capability and the cycling ability of lithium polymer batteries. The relationship between polymer
electrolyte design, lithium transport properties and battery performance are investigated in this research. 相似文献
16.
Abstract
The Andrade relation for the viscosity of liquid metals has been reformulated in terms of the Debye temperature for liquid metals. This semi-empirical relation has been extended to obtain a relation to calculate the composition and temperature dependence of the viscosity of liquid alloys using parameters which can be determined experimentally. The important inputs are the enthalpy of formation, ΔH, and the excess volume of mixing, ΔΩ. The composition dependence of the viscosity and its deviation from linear behavior could be positive or negative depending on the sign and magnitude of ΔH and ΔΩ. Several limiting cases of the semi-empirical relation for the viscosity of liquid alloys are compared and discussed. The results of the semi-empirical relation for viscosity isotherms for binary and ternary liquid alloys are mostly in reasonable agreement with available experimental results. 相似文献17.
Joseph E. Earley Sr. 《Foundations of Chemistry》2006,8(3):271-283
During a long and distinguished career, Belgian physical chemist Ilya Prigogine (1917–2003) pursued a coherent research program in thermodynamics, statistical mechanics, and related scientific areas. The main goal of this effort was establishing the origin of thermodynamic irreversibility (the ‘‘arrow of time’’) as local (residing in the details of the interaction of interest), rather than as global (being solely a consequence of properties of the initial singularity – the ‘‘Big Bang’’). In many publications for general audiences, he stated the opinion that this scientific research had great philosophical importance. Prigogine and his colleagues considered that the most recent stages of this research program have been successful, so that the local origins of the arrow of time are now established. There is no scientific consensus as to whether or not this claim is valid. Similarly, there is no consensus on whether the competing global (initial singularity) explanation has been proven. 相似文献
18.
S. K. Tripathi Amrita Jain Ashish Gupta Manju Mishra 《Journal of Solid State Electrochemistry》2012,16(5):1799-1806
The development of polymer gel electrolyte system with high ionic conductivity is the main objective of polymer research.
Electrochemical devices based on lithium ion-conducting polymer electrolyte are not safe due to the explosive nature of lithium.
An attempt has been made to synthesize magnesium ion-conducting polymeric gel electrolytes, poly (vinylidene fluoride-co-hexafluoropropylene)–propylene
carbonate–magnesium perchlorate, PVdF(HFP)-PC–Mg(ClO4)2 using standard solution-cast techniques. The maximum room temperature ionic conductivity of the synthesized electrolyte system
has been observed to be 5.0 × 10−3 S cm−1, which is quite acceptable from a device fabrication point of view. The temperature-dependent conductivity and the dielectric
behavior were also analyzed. The pattern of the temperature-dependent conductivity shows the Arrhenius behavior. The dielectric
constant ε
r and dielectric loss ε
i increases with temperature in the low-frequency region but almost negligible in the high-frequency region. This behavior
can be explained on the basis of electrode polarization effects. The real part M
r
and imaginary part M
i
versus frequency indicate that the systems are predominantly ionic conductors. Further, the synthesized electrolyte materials
have been checked for its suitability in energy storage devices namely redox supercapacitor with conducting polymer polypyrrole
as electrode materials, and finally, it was observed that it shows good capacitive behavior in low-frequency region. Preliminary
studies show that the overall capacitance of 22 mF cm−2 which is equivalent to a single electrode specific capacitance of 117 F gm−1 was observed for the above said supercapacitors. 相似文献
19.
E. Moran C. Cattaneo H. Mishima B. A. López de Mishima S. P. Silvetti J. L. Rodriguez E. Pastor 《Journal of Solid State Electrochemistry》2008,12(5):583-589
Ammonia electro-oxidation on Pt–Ir alloys has been studied applying cyclic voltammetry and differential electrochemical mass
spectrometry (DEMS), and the results were compared with pure Pt. Bimetallic alloys were prepared by electrodeposition and
characterized using X-ray diffractometry (XRD) and Auger spectroscopy, before and after oxidation of ammonia. Pt/Ir atomic
composition was 70:30 obtained from 1:1 solutions. Substitution alloys were established where Ir atoms replace Pt positions
in the face-centered cubic structure. Preferential crystal orientations were detected in the electrodeposits with the development
of a crystallographic texture. DEMS showed that N2 is the main product during ammonia oxidation for both Pt and Pt–Ir, but the formation of nitrogen oxides is observed for
E > 0.8 VRHE. The yield of N2 is higher for the alloy, which also displays lower poisoning of the surface when increasing ammonia concentration. These
results confirm Pt–Ir alloys as alternatives to Pt electrodes concerning ammonia oxidation. Finally, it was observed that
XRD patterns, as well as texture coefficient values, change after using the electrodeposits for ammonia oxidation, with the
less compact planes the more affected ones.
Dedicated to Prof. Dr. Teresa Iwasita on the occasion of her 65th birthday in recognition of her numerous contributions to
interfacial electrochemistry. 相似文献
20.
The evaporation of single triethyl phosphate (TEP) micro-droplets containing a high molecular weight polymer, poly(methyl
methacrylate) (PMAA), was inves-tigated using an electrodynamic trap and light scattering measurements to explore the suppression
of evaporation by the additive. Pure-component evaporation rates were measured to determine the vapor pressure over a range
of temperatures, and the polymer was found to significantly decrease the evaporation rate. A numerical solution of the problem
of simultaneous solvent evaporation and polymer diffusion within the droplet indicated a rapid build-up of PMMA at the surface
of the drop, but vapor/liquid thermodynamic considerations alone do not account for the observed reduction in the evaporation
rate for the droplets containing PMMA. After significant evaporation of TEP occurred, the ultra-low evaporation rate was measured
using changes in the Raman spectra associated with morphology-dependent resonances. The evaporation in this regime appears
to be controlled by the rate of solvent molecules diffusing through the polymer matrix.
Received: 17 June 1997 Accepted: 24 October 1997 相似文献