A Double Cation–π-Driven Strategy Enabling Two-Dimensional Supramolecular Polymers as Efficient Catalyst Carriers

The cation–π interaction is a strong non-covalent interaction that can be used to prepare high-strength, stable supramolecular materials. However, because the molecular plane of a cation-containing group and that of aromatic structure are usually perpendicular when forming a cation–π complex, it is difficult to exploit the cation–π interaction to prepare a 2D self-assembly in which the molecular plane of all the building blocks are parallel. Herein, a double cation–π-driven strategy is proposed to overcome this difficulty and have prepared 2D self-assemblies with long-range ordered molecular hollow hexagons. The double cation–π interaction makes the 2D self-assemblies stable. The 2D self-assemblies are to be an effective carrier that can eliminate metal-nanoparticle aggregation. Such 2D assembly/palladium nanoparticle hybrids are shown to exhibit recyclability and superior catalytic activity for a model reaction.     

“Structure and Properties of Polymers”英文版教材

英文版Structure and Properties of Polymers一书已由英国Alpha Science International Ltd出版,全世界发行。这是高分子学科中由我国学者编著的第一本英文版教材,由国外出版社出版。论文叙述了该书中文版的成书历史和出版背景,以及英文版书出版的由来和写作历程。强调英文书写作时要特别重视所引文献、图表和示意图等的著作版权问题,当查不到插图的原著时,要及时更换。论文还交代了英文版书对原中文版书中不妥之处的修改。希望该书对推介我国高分子物理的成就以及推介我国高分子学科的教学起到积极的作用。     

Arenes and Heteroarenes C−H Functionalization Under Enabling Conditions: Electrochemistry,Photoelectrochemistry & Flow Technology

C−H bond functionalization generates molecular complexity in single-step transformation. However, the activation of C−H bonds requires expensive metals or stoichiometric amounts of oxidizing/reducing species. In many cases, they often require pre-functionalization of starting molecules. Such pre-activating measures cause waste generation and their separation from the final product is also troublesome. In such a scenario, reactions activating elements generating from renewable energy resources such as electricity and light would be more efficient, green, and cost-effective. Further, incorporation of growing flow technology in chemical transformation processes will accelerate the safer accesses of valuable products. Arenes & heteroarenes are ubiquitous in pharmaceuticals, natural products, medicinal compounds, and other biologically important molecules. Herein, we discussed enabling tools and technologies used for the recent C−H bonds functionalization of arenes and heteroarenes.     

Power‐to‐Syngas: An Enabling Technology for the Transition of the Energy System?

Power‐to‐X concepts promise a reduction of greenhouse gas emissions simultaneously guaranteeing a safe energy supply even at high share of renewable power generation, thus becoming a cornerstone of a sustainable energy system. Power‐to‐syngas, that is, the electrochemical conversion of steam and carbon dioxide with the use of renewably generated electricity to syngas for the production of synfuels and high‐value chemicals, offers an efficient technology to couple different energy‐intense sectors, such as “traffic and transportation” and “chemical industry”. Syngas produced by co‐electrolysis can thus be regarded as a key‐enabling step for a transition of the energy system, which offers additionally features of CO₂‐valorization and closed carbon cycles. Here, we discuss advantages and current limitations of low‐ and high‐temperature co‐electrolysis. Advances in both fundamental understanding of the basic reaction schemes and stable high‐performance materials are essential to further promote co‐electrolysis.     

A review of: “Gas Separation Technology”

Abstract

E.F. Vansant and R. Dewolfs, Eds. Elsevier, Amsterdam, 1990; (Process Technology Proceedings, 8), hard bound, 700 pages, $233.00     

“Hydrophobic Bonds”? A Study of Long-Range Interactions in Polymers

Inelastic neutron scattering spectroscopy offers a unique method of studying the intermolecular forces binding molecular crystals and polymers. The results from incoherent and coherent neutron spectroscopy are here related. For polyethylene they lead to the conclusion that the interchain forces are nearly two orders of magnitude weaker than the valence forces in a chain.     

“Smart” Polymers: Physicochemical Characteristics and Applications in Bio-Separation Strategies

In recent years, smart polymers (SPs), which are also referred to as bio-responsive polymers, have gained considerable attention as a unique class of polymers and their applications have been increasing significantly. These so-called “smart” polymers, either synthetic or biological, have been defined as “polymers designed to respond or undergo physical and structural conformational changes/rearrangement in response to slight changes in their surrounding environment”. They are categorized as thermo-, pH-, electro- and magneto-responsive polymers. The advances in upstream bio-production stages and the high cost associated with downstream chromatographic techniques have pushed the development of new alternatives. In this context, the use of SPs, in combination with non-chromatographic technologies, represents a useful approach to the development of new downstream operation units. With the key scientific advancements, SPs have become the “next generation” of the bio-separation tool for eco-friendlier and cost-effective purification. This review describes the different characteristics and classifications of various “smart” polymers available for use in bio-separation strategy. Focus is also given to the recent advances in SP inclusion in the improvement of alternative non-chromatographic methods in downstream bioprocessings.     

Development of Bionic Polymers

Bionics, an artificial imitation of natural products, has always been a forever dream in the fairy tale or scientific fiction when we were childhood and children live now. However, the development of science in molecular scale makes this dream of childhood and manhood realize today. Bionics, a branch of science concerned with application the data about the functioning of biological system to the solution of engineering problems, become top-priority of science in the 21st century. However, few …     

Fuel Processing Technology特辑-“低阶煤利用”征稿启事

Elsevier出版社将在能源领域的重要期刊Fuel Processing Technology出版低阶煤利用特辑,中国科学院山西煤炭化学研究所李文研究员作为该特辑的客座编辑,负责稿件的征集、送审、接受等工作,现面向国内外公开征稿。稿件内容包括:与低阶煤利用相关的原创性文章或综述,如:低阶煤及其衍生物的特性、低阶煤提质、提级利用和热化学转化等方面的内容。     

Interactions Between Polymers and Nanoparticles: Formation of “Supermicellar” Hybrid Aggregates

Abstract

When polyelectrolyte‐neutral block copolymers are mixed in solutions to oppositely charged species (e.g., surfactant micelles, macromolecules, proteins, etc.), there is the formation of stable “supermicellar” aggregates combining both components. The resulting colloidal complexes exhibit a core‐shell structure, and the mechanism yielding to their formation is electrostatic self‐assembly. In this contribution, we report on the structural properties of “supermicellar” aggregates made from yttrium‐based inorganic nanoparticles (radius 2 nm) and polyelectrolyte‐neutral block copolymers in aqueous solutions. The yttrium hydroxyacetate particles were chosen as a model system for inorganic colloids, and also for their use in industrial applications as precursors for ceramic and opto‐electronic materials. The copolymers placed under scrutiny are the water‐soluble and asymmetric poly(sodium acrylate)‐b‐poly(acrylamide) diblocks. Using static and dynamical light‐scattering experiments, we demonstrate the analogy between surfactant micelles and nanoparticles in the complexation phenomenon with oppositely charged polymers. We also determine the sizes and the aggregation numbers of the hybrid organic–inorganic complexes. Several additional properties are discussed, such as the remarkable stability of the hybrid aggregates and the dependence of their sizes on the mixing conditions.     

Composite Materials Based on Polylactide and Poly-3-hydroxybutyrate “Green” Polymers

Blends of polylactide with low-density polyethylene and of poly-3-hydroxybutyrate with synthetic ethylene–propylene rubber with the component weight ratios of 30 : 70, 50 : 50, and 70 : 30 were prepared and studied in comparison with the pure components. The thermal characteristics of these blends were determined by differential scanning calorimetry. The melting point of polyhydroxybutyrate and polylactide in the blends changes insignificantly, by 1–2°C. The dependence of the morphology on the composition for both polymer systems was examined by scanning electron microscopy. The physicomechanical properties of the samples are determined by the major phase. The blends undergo biodegradation in soil at 20 ± 3°С. The process occurs faster for blends of polyhydroxybutyrate with ethylene–propylene rubber of all the compositions studied.     

“Brown-Ring”-Related Coordination Polymers of the Quartet-{FeNO}7 Chromophore

A conspicuous detail of the so-called brown-ring test (the analytical test on nitrate) is the reddish color of the bottom layer of concentrated sulfuric acid, which develops upon the bleeding of the brown layer into the acid. Crystals of the same color form from a solution of ferrous sulfate in concentrated sulfuric acid on saturation with gaseous nitric oxide. The structure of this H₃O[{Fe(NO)(μ₄-SO₄)(μ₂-SO₄)_0.5}_n/n] ( 1a ) is made up from infinite chessboard-type layers with sulfur on the field junctions and Fe(NO) moieties below the black and above the white fields. An Fe–N–O angle of about 160° causes disorder in the tetragonal space group I4/mmm. A similar crystal pathology was found in the related [{Fe(MeOH)(NO)(μ₄-SO₄)}_n/n] ( 1b ) in the same crystal class. A one-dimensional coordination polymer is formed in crystals of a third compound that comprises the Fe(NO)O₅ coordination pattern, namely the brown oxalato species [{Fe(H₂O)(NO)(μ₂-ox)}_n/n · H₂O] ( 2 ). A still larger NO tilt of about 156° is not obscured by disorder in the triclinic crystals of 2 .     

Erratum to: “New Opportunities in Synthesis of Fullerene-Containing Polymers of Allyl Series”

Russian Journal of Applied Chemistry -     

Synthesis and Properties of Oligo-/Polymers Based on a “Flexible” Swivel-Cruciform Structure

We have introduced the concept of the so-called swivel type cruciforms as a highly flexible tool to tune the molecular properties from amorphous to highly crystalline features. Simple alkoxy substituted binaphthyl building blocks have been introduced randomly into poly(9,9-dioctylfluorene) (PFO) thereby suppressing the formation of side-chain crystallization. On the other hand the all aryl penta-thiophene based cruciform exhibited strong π–π interaction between the arms and gave one of the highest values reported to date for wet processed organic field effect transistors (OFETs) utilising oligothiophenes.     

β-Cyclodextrin-Mediated Stereoregularity in Polyacrylonitrile Polymers

Abstract

Polyacrylonitrile polymers produced in the presence of molar equivalents of β-cyclodextrin (BCD) showed variation in stereoregularity. Thus, an increase in the acrylonitrile:BCD ratio showed an increase in isotacticity in the polymers formed. Inclusion complexation of acrylonitrile by BCD was detected by both ¹H-NMR spectroscopy and UV-Vis spectroscopy, which gave a binding constant value of 7242 ± 360 M^?1 for the 1:1 complex.     

Polymers for Electro‐Optical Modulation

Second‐order nonlinear optical (NLO) properties of polymeric materials have been attracting a lot of attention, especially for such potential applications as fast waveguides electrooptic (EO) modulation and frequency‐doubling devices. For these photonic applications, the performance of the NLO materials has to be optimized. This requires not only a fundamental knowledge of inter‐relationship between their chemical and NLO properties, but new technologies competitive or superior to existing ones as well. This review focuses on the synthesis of NLO polymers including chromophore design, and the comparison among comprehensive EO polymer systems. Moreover, characterization and device fabrication of electro‐optical polymer planar waveguides are also reported in this review.     

From 3′-Keto-Isomaltulose to Polymers

Abstract

A new method was developed to prepare polymers with a saccharide in the main chain without blocking and deblocking procedures. The microbial oxidation product of isomaltulose, 3′-keto-isomaltulose, was converted to a diamine by reductive amination. The resulting diamine was employed as a difunctional monomer for direct polyaddition with diisocyanates. The polyureas formed were characterized by IR, ¹³C NMR, light scattering, and viscosity measurements.     

International Conference on Liquid Crystal Polymers

Under the sponsorship of the International Union of Pure and Applied Chemistry (IUPAC)and Chinese Chemical Society, the International Conference on Liquid Crystal Polymers was heldat the Twenty-First Century Hotel, Beijing China, in 6-9 September 1994. The conference Chair-man and Secretary general were Professors Q. F. Zhou of Peking University and X. J. Wang of