基于超分子化学方法制备自愈合聚合物材料的研究进展

本文综述了超分子化学方法制备自愈合聚合物材料的研究进展,着重介绍了利用氢键、π-π键、离子键等非共价键主-客体相互作用来制备自愈合聚合物材料的研究现状。     

Role of surface chemistry on electric double layer capacitance of carbon materials

A large number of porous carbon materials with different properties in terms of porosity, surface chemistry and electrical conductivity, were prepared and systematically studied as electric double layer capacitors in aqueous medium with H₂SO₄ as electrolyte. The precursors used are an anthracite, general purpose carbon fibres and high performance carbon fibres, which were activated by KOH, NaOH, CO₂ and steam at different conditions. Among all of them, an activated anthracite with a BET surface area close to 1500 m²/g, presents the best performance, reaching a value of 320 F/g, using a three-electrode system. The results obtained for all the samples, agree with the well-known relationship between capacitance and porosity, and show that the CO-type oxygen groups have a positive contribution to the capacitance. A very good correlation between the specific capacitance and this type of oxygen groups has been found.     

Sorption of bioactive materials on carbon

Adsorption of biologically active materials on carbon is reviewed. Solvent desorption of polycyclic aromatic hydrocarbons (PAH) is shown to be strongly dependent on PAH size and surface concentration. On carbon black, a model carbonaceous adsorbent, type II isotherms are obtained for the adsorption of pyrene from cyclohexane solution and cyclohexane from the vapor phase. Isosteric heats of adsorption for cyclohexane show a broad maximum at θ ~ 0.4, whereas the net heat for pyrene decreases steeply from an initial maximum to a limiting value at surface concentrations >30 μg/m². PAH desorption in organic solvents increases in the presence of polymers, particularly at very low loadings of PAH. In aqueous media, PAH are strongly retained by carbon and exhibit negligible bioavailability in physiologic fluids and in lipid bilayer membrane systems.     

Effect of surface chemistry on electrochemical storage of hydrogen in porous carbon materials

Porous carbon materials, with different porosities and surface chemistry have been prepared and characterized to obtain a better understanding of the mechanism of the electrochemical storage of hydrogen. The hydrogen storage capacity depends, not only on the porosity of the material, but also on the surface chemistry, which is a critical factor. The results show that the higher the amount of surface oxygen groups, the lower is the hydrogen uptake. Measurement of the number of active carbon sites shows the important role of the unsaturated carbon atoms in the process. In situ Raman spectroscopy has been used in order to further explore the structural changes in the carbon material during the charge-discharge processes. This technique has allowed us to observe the formation of the C(sp²)H bonds during the cathodic process and its reversibility during the oxidation step.     

重氮盐用于无机材料的表面改性研究进展

重氮盐的表面改性是一种新型有效的表面改性方法,可实现对无机、有机、生物材料的改性。综述了重氮盐用于无机材料表面改性的特点及方法,如电化学还原、氧化还原、UV辐照接枝、热化学反应、机械接枝、超声波和微波辅助改性,并重点介绍了近年利用重氮盐对碳纳米管、石墨、玻璃碳、金属、半导体、石英和纳米金刚石等无机材料的表面改性及应用。     

Characterization of the surface chemistry of carbon materials by potentiometric titrations and temperature-programmed desorption

Two methods currently used to characterize oxygen-containing functional groups on the surface of carbon materials are compared, namely potentiometric titration (PT) and temperature-programmed desorption (TPD). Two materials were used, activated carbon and multi-walled carbon nanotubes, which were subsequently modified by oxidative treatments in order to produce samples with different amounts of surface groups. The concentrations of carboxylic acid groups determined by both techniques are in good agreement, but the quantitative result obtained by TPD is closer to the analytical concentration of the species obtained by elemental analysis. Discrepancies between the quantitative results are more pronounced at higher pK_a values (weak acids), where the concentrations determined by PT are lower than those obtained by TPD. This directly reflects the effects of neglecting the electrostatic interaction parameter. The TPD method was particularly suited for the characterization of samples modified with ethylenediamine, which is anchored to specific oxygenated groups. PT results are useful to describe the material behaviour in aqueous solutions, where the activity of the surface groups depends not only on their concentrations, but also on their environment.     

基于冠醚的离子识别响应型智能材料研究新进展

金属离子对生物体的生命活动起着核心的作用,而一些重金属离子(如Pb²⁺、Hg²⁺)在很低浓度时就对生物具有极强的毒性;因此,研究具有金属离子识别特性的智能材料具有重要的理论价值和实用意义。冠醚具有选择性地络合金属离子的能力,研究者们将冠醚的离子识别特性与聚(N-异丙基丙烯酰胺)的相变行为特性相结合制备了一系列离子识别响应型智能材料。综述了近年来基于18-冠-6和15-冠-5两种冠醚分子的离子识别响应型智能材料的研究新进展。目前,基于冠醚的离子识别响应型智能材料仍多处于基础研究阶段,还需要进一步系统深入研究和开发完善。     

UV polymerization‐based surface modification technique for the production of bioactive packaging

The term bio‐active packaging refers to a packaging material that has been modified by the attachment or immobilization of bioactive components on the food contact surface. This article describes a novel, economical, and feasible technique for embedding bioactive components in energy curable food contact resins. While the technique is versatile and potentially applicable to any antimicrobial or bioactive compound; the proof of concept discussed in this article has focused on enzyme immobilization. Glucose oxidase (GOx) and catalase were used as representative enzymes. These oxidoreductases are very sensitive to inactivation by extrinsic factors and therefore present a challenging model for immobilization. Embedding of activity occurred via UV polymerization of commercial polymer coatings. The efficiency of immobilization and the performance of bioactive packaging were tested in both food simulants and actual food products. In both cases immobilization resulted in food contact surfaces with high retained enzyme activity as demonstrated by oxygen removal. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The chemistry of tissue adhesive materials

Each year millions of people sustain traumatic or surgical wounds, which require proper closure. Conventional closure techniques, including suturing and stapling, have many disadvantages. They inflict additional damage on the tissue, elicit inflammatory responses and have a relatively long application time. Especially for the more demanding wounds, where fluids or gasses are to be sealed off, these techniques are often insufficient. Therefore, a large variety of tissue adhesives, sealants and hemostatic agents have been developed. This review provides an overview of such tissue adhesive materials from a polymer chemistry perspective. The materials are divided into synthetic polymer, polysaccharide and protein based adhesives. Their specific properties and behavior are discussed and related to their clinical application. Though each type has its specific advantages, yet few have become standard in clinical practice. Biomimetic based adhesives and other novel products have shown promising results but also face specific problems. For now, the search for better adhering, stronger, easier applicable and cheaper adhesives continues and this review is intended as starting point and inspiration for these future research efforts to develop the next generation tissue adhesives.     

Molecular origin of unusual physical and mechanical properties in novel phenolic materials based on benzoxazine chemistry

The effect of temperature on hydrogen bonding was investigated by measuring the integrated infrared absorbance of various hydrogen-bonding modes as a function of temperature. It was found that conformationally preferred hydrogen- bonding modes maintain constant intensities over the wide temperature ranges studied for both polybenzoxazines and a novolac-type phenolic resin. In particular, the O— — —H— — —N hydrogen bond shows strong bonding that does not change over the temperature range. On the other hand, statistically distributed hydrogen bonding is more sensitive to the temperature change and its infrared intensities start decreasing around the β-transition of polybenzoxazines. The unusual physical and mechanical properties of polybenzoxazines, including volumetric expansion upon polymerization, high moduli, and high glass transition temperatures, are explained based on the complex hydrogen bonding. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1299–1306, 1998     

计算化学在多孔储氢材料研究中的应用

计算化学方法在多孔储氢材料的应用主要有4个方面:1)研究多孔材料的储氢性能;2)研究多孔材料对氢气的吸附热;3)研究储氢机理;4)设计新型多孔储氢材料。综述了计算化学方法在多孔储氢材料研究中取得的成果和最新进展,展望了计算化学方法在储氢领域的应用前景。     

A perspective of surface chemistry

Some highlights in the development of experimental strategies in the study of surface chemistry and catalysis over the last two decades are discussed. The role of adsorbate activation by surface oxygen in providing impetus and direction to research over the last two decades is considered and emphasis given to recent work at Cardiff in exploring the role that surface transients can play in determining reaction pathways. Evidence for very efficient kinetic routes to products but involving immeasurably small concentrations of surface species raises general issues relating to the more traditional approach to catalysis based on for example a Langmuir- Hinshelwood mechanism.     

Development of microfibers for bone regeneration based on alkali-free bioactive glasses doped with boron oxide

In this paper, we present a new series of alkali-free bioactive glasses (BG) based on FastOs^® composition (38.49 SiO₂ – 36.07 CaO – 19.24 MgO – 5.61 P₂O₅ – 0.59 CaF₂, expressed in mol %), which was modified by partially replacing silicon dioxide network-former with boron trioxide network-former, utilizing calcium oxide as a charge compensator. The main objective of this study was to obtain a new family of bioactive glasses suitable for the fabrication of glass fibers. The BGs were prepared by melt quenching technique and their structural and thermal properties were determined. Glass rods were used to obtain fibers by the classic drawing technique. The bioactivity of the fibers was subsequently assessed through immersion tests in simulated body fluid (SBF) to establish their ability to form hydroxyl carbonated (HCA) apatite onto their surfaces. Glasses with moderate substitution of SiO₂ with B₂O₃ exhibited enhanced thermal properties, allowing to significantly suppress the crystallization trend, and favoring to draw the fibers. The structure of the studied glasses was obtained by NMR spectroscopy. The structure-property correlations were established by their relationship to the configurational entropy. Smaller amounts of substitution resulted in larger entropy of the glasses. Moreover the SBF tests revealed an extensive formation of HCA, comparable to the parent FastOs^®BG composition, which assures fast bonding to the bone. Thus, presented glass fibers may be considered as promising materials for wool-like bone implants or as reinforcing constituent of biopolymer matrix composites.     

Protein chemistry on the surface of living cells

The interplay between carbohydrates, lipids, and proteins determines the stability and flexibility as well as the adhesive and responsive features of the surfaces of all cells. The molecular understanding of the interactions among and between the different classes of these biomolecules is rudimentary at best, a lack of suitable experimental methods being the major reason. Here we discuss a new approach for the specific labeling of fusion proteins of carrier proteins with synthetic compounds on cell surfaces and describe how this approach can be used to investigate the properties of the labeled molecules.     

Medical hydrogels based on bioactive compounds. Synthesis,properties, and possible application for preparing bactericidal materials

Several physicochemical analytical methods were used to study aqueous solutions and hydrogels based on L-cysteine and silver nitrate. It was found that anions played a decisive role in forming the threedimensional gel-network in dilute silver-cysteine solutions. The ability to use silver-cysteine solutions and hydrogels to prepare bactericidal fibers and fabrics was examined.     

Development of high‐modulus thermoset materials based on bioglycerol

A high‐value application of crude bioglycerol in polymers was developed. In this application, bioglycerol was first transformed into a highly polyunsaturated resin (MAGLYMA) through maleinization–methacrylation reactions, under mild conditions (80–90 °C, 1–2 h). The resin was copolymerized with methyl methacrylate (MMA) (20%–50%) at room temperature over 8 h, affording rigid materials. The effect of MMA content on the mechanical and thermal properties was evaluated. The flexural modulus, flexural strength and surface hardness of the materials were around 3800 MPa, 130–180 MPa and 77 (Shore D), respectively. T_g values were in the range 92–105 °C. It is remarkable that excellent mechanical and thermal properties were obtained using a low concentration of MMA (20%). In particular, the mechanical properties of this material were better than those obtained for a commercial unsaturated polyester thermoset. © 2019 Society of Chemical Industry     

Development of a heavy-current storage capacitor based on carbon fibre materials

The basic structural features of a double-layer energy storage capacitor, the characteristics of the acting mock-up of such a capacitor, and the features of use of woven and nonwoven materials, including activated carbon fibre materials, in it were examined. The capacitor has a capacitance of up to 400 F and provides a starting current of up to 700 A, so that it can be successfully used in starting a Volga automobile in winter. A. Ya. Lyalyushkin and A. G. Zotov participated in the experimental part of the research. Translated from Khimicheskie Volokna, No. 3, pp. 35–38, May–June, 1997.