聚合物改性水玻璃均相杂化液对速生杨木的改性

将丙烯酰胺单体在钠水玻璃溶液中聚合制成水玻璃-聚丙烯酰胺均相杂化液,通过浸渍法使杂化液与速生杨木材复合,制成无机/有机木材复合材。SEM、FT-IR表征了速生杨木与杂化前驱液复合前后的结构和形貌变化,研究了复合木材的热稳定性及力学性能的变化,结果表明,用该均相杂化液改性的复合木材WPG为31.6%时,其氧指数为50.3%;并且与素材的力学性能相比,复合木材的抗弯曲强度较素材提高了11.2%,弹性模量提高了18.2%,其径面、弦面和端面的硬度分别提高了15.6%、17.3%和26.2%。     

水与废水处理用无机/有机杂化复合絮凝剂研究进展

无机/有机杂化复合絮凝剂具有价廉、生态安全与健康、絮凝效率高等特点,其研发及在废水中的应用已经引起研究者和用户的广泛关注。本文对该复合絮凝剂类型、制备方法、性能及其应用进行了综述,同时对其絮凝作用机理进行了简要评述,提出了当前无机/有机杂化复合絮凝剂存在的问题和几点建议。     

化学键组装稀土/无机/有机聚合物杂化光功能材料的最新研究进展

本文针对近五年来光功能稀土/无机/有机聚合物杂化材料的最新进展进行了评述,其重点着眼于高分子化合物作为构筑基元的发光稀土杂化材料体系的化学键组装.内容主要涉及稀土有机高分子杂化材料、配位键构筑的稀土/无机/有机高分子杂化材料、共价键构筑的稀土/无机/有机高分子杂化材料、自由基聚合构筑的稀土/无机/有机高分子杂化材料几个重要方面.主要结合我们自己的近期研究工作,通过系统总结来展现该领域的研究现状并提出未来展望.     

硫醇-烯/炔点击化学制备有机/无机杂化材料

有机/无机杂化材料因其独特、优异的结构和性能已经成为目前材料领域的研究热点,硫醇-烯/炔点击化学是近年发展起来的一类新型点击化学,以其反应条件温和、速率快、产率高、产物容易分离以及高度选择性等优点受到国内外研究者的广泛关注。本文综述了近年来硫醇-烯/炔点击化学制备有机/无机杂化材料的研究进展,重点介绍了利用硫醇-烯/炔点击化学制备硅类、碳类、金属及金属氧化物类有机/无机杂化材料,并归纳了这些有机/无机杂化材料在生物医用、环境保护、光电材料等方面的应用,最后展望了硫醇-烯/炔点击化学制备有机/无机杂化材料未来的发展方向。     

有机-无机杂化骨修复材料

寻找理想的骨修复材料一直是骨科领域的研究热点之一。骨修复材料已由最初单纯取代天然骨组织的惰性材料向具有诱导骨组织再生功能的生物活性材料发展,其中有机-无机杂化材料由于有机和无机组分在分子/纳米水平的复合使其能够最大程度地实现二者的优势互补和协同优化,近年来受到广泛关注。本文着重介绍了有机-无机杂化骨修复材料近些年来的研究进展,并对其发展趋势进行了展望。     

杂化太阳电池中异质结界面的修饰及其对电池光电性能的影响

有机-无机杂化太阳电池综合了有机、无机材料的优点,成本低、理论效率高,受到人们的广泛关注.杂化太阳电池的光活性层由无机半导体和有机共轭聚合物复合而成.当光照射到活性层上时,共轭聚合物吸收光子产生激子(电子-空穴对);激子迁移到有机给体-无机受体的异质结界面处发生解离而产生自由电子和空穴;自由电子和空穴分别向无机半导体和有机聚合物传输,从而实现电荷的分离和传导.激子在有机-无机异质结界面处的分离效率是影响电池性能的一个重要因素.有机、无机两相材料往往因为接触面积小以及相容性差使此两相材料接触不佳,激子迁移到此界面不能有效分离,从而严重影响了杂化太阳电池的效率.这个问题可以通过此界面的修饰加以改善.本文即综述了有机-无机异质结界面修饰的方法、作用和意义,并展望了杂化太阳电池未来的发展趋势和应用前景.     

Cd基化合物纳米晶-有机聚合物杂化太阳能电池研究进展

有机-无机杂化太阳能电池因其结合了有机材料和无机材料各自的优势而引起了人们的广泛关注和研究. Cd基化合物纳米晶因其具有制备方法简单、尺寸及形貌可控、载流子迁移率高和稳定性好等优点而成为最早被研究的一类无机受体. 本文介绍了有机-无机杂化太阳能电池的结构及原理, 分析了影响有机-无机杂化太阳能电池效率的三个主要因素, 分别是开路电压(V_oc)、短路电流(J_sc)和填充因子(FF). 从改善Cd基化合物纳米晶的合成方法, 增加Cd基化合物纳米晶和有机聚合物间的界面接触, 以及优化Cd基化合物纳米晶和有机聚合物所用溶剂和所占比例等方面阐述了近年来Cd基化合物纳米晶-有机聚合物杂化太阳能电池的研究进展. 并展望了Cd基化合物纳米晶-有机聚合物杂化太阳能电池的发展方向.     

含钒无机有机杂化材料的合成、结构与性质

含钒无机有机杂化材料的结构复杂多样,在吸附、氧化还原、电化学、催化、光学、磁学以及多孔、手性材料研究等方面应用前景广阔,引起人们广泛关注。本文综述了含钒无机有机杂化材料研究的最新进展,介绍了合成含钒无机有机杂化材料的主要方法,按照有机组分与无机骨架作用的方式分类总结了含钒无机有机杂化材料的结构,介绍了其在离子交换、电化学、磁学、光学、催化等方面的应用,并展望了该类材料的研究前景和意义。     

有机-无机杂化膜的研究进展

有机-无机杂化膜结合了传统有机膜与无机膜的优良性能,已成为膜领域的研究热点之一。本文综述了有机-无机杂化膜的研究现状,归纳了有机-无机杂化膜的分类、制备技术、应用及其优越性,并针对现存的问题及今后的研究发展提出了一些建议。     

氧化石墨烯在仿生合成中的应用及研究

氧化石墨烯薄片的边缘含有大量的含氧功能团(如羧基等),这些官能团可以有效地与金属离子作用而成为晶体的成核位点,从而使得氧化石墨烯具备模板功能而用于仿生合成。论文综述了氧化石墨烯用作模板剂在仿生合成有机/无机杂化材料方面的应用研究进展,介绍了其基本原理,阐述了不同类型杂化材料的制备方法,并展望了石墨烯基有机/无机杂化材料的发展新趋势。     

Properties of Aqueous Polyurethane Dispersion Modified by Epoxide Resin and Their Use as Adhesive

The aqueous polyurethane hybrid dispersion modified by the epoxy resin were synthesized using 1,4-butanediol ( BDO ) and dimethylolpropionic(DMPA) as chain extenders. A kind of automobile interior decoration adhesive was made by the modified hybrid dispersions. Effects of the content and the kinds of epoxide resin on the properties of dispersions and dispersion-cast films such as appearance, pot life, viscosity, particle size, molecular mass, hardness, swelling in water, contact angle, strength of stress, elongation at break, and other mechanical properties were studied. At the same time the effect of the E20 content on the peel strength of the adhesive for several automobile interior decoration substrates such as rubber/wood, poly(vinyl chloride)/wood; leather/wood, sponge/wood was investigated. The experimental results show that when the epoxy resin E20 content was 8%, the modified polyurethane hybrid dispersions possess better properties and the adhesive made by the modified dispersions posses better adhesion for automobile interior decoration substrates. The stress-strain curve of the modified aqueous polyurethane hybrid dispersions films shows the modified aqueous cast films possess better rigidity and toughness.     

Identification and expression analysis of genes encoding putative cellulose synthases (CesA) in the hybrid aspen, Populus tremula (L.) × P. tremuloides (Michx.)

Cellulose is synthesized in plant cell walls by large membrane-bound protein complexes proposed to contain several copies of the catalytic subunit of the cellulose synthase, CesA. Here we report identification of 10 distinct CesA genes within a database of 100,000 ESTs of the hybrid aspen, Populus tremula (L.) × P. tremuloides (Michx.). Expression analyses in normal wood undergoing xylogenesis and in tension wood indicate xylem specific expression of four putative CesA isoenzymes, PttCesA1, PttCesA3-1, PttCesA3-2 and PttCesA9. Both the protein sequences and the expression profiles of PttCesA3-1 and PttCesA3-2 are very similar, and they may thus represent redundant copies of an enzyme with essentially the same function. Further, one of the generally more constitutively expressed CesA genes, PttCesA2, seems to be activated on the opposite side of a tension wood induced stem, while PttCesA6 appears to be more specific for leaf tissues. The rest of the hybrid aspen CesA genes were found to be relatively evenly expressed over the poplar tissues hereby studied.     

Interpenetration of wood with NH2R-functionalized silica xerogels anchoring copper(II) for preservation purposes

Interpenetration of wood samples of pine sapwood (Pinus sylvestris L.) with hybrid inorganic–organic silica xerogels bearing amine functions able to coordinate copper(II) cations has been successfully carried out. These materials have been prepared by sol–gel processing TEOS/APTES mixtures inside the wood. Solid state ²⁹Si NMR data provide evidence that the interpenetrated xerogel material has the same degree of condensation of the corresponding xerogel formed outside the wood. Copper(II) is effectively vehiculated inside the wood by coordination linkages with two ammine functions well evidenced by ESR measurements. SEM/EDX investigations show that the chlorine/copper atomic ratio inside the wood is lower than that of the starting salt CuCl₂, suggesting an exchange reaction with silanol groups with the formation of Si–O–Cu linkages and HCl. This reaction could be promoted by the excess of amine functions with formation of ammonium chloride species which remain onto the surface of the wood and in the mother solution owing to a higher degree of condensation. Sodium silicate was tested in place of TEOS in order to have a cheaper and ethanol-free formulation. However, gel penetration results significantly lower than that of the corresponding formulation containing TEOS and preservation performance are lower than that of TEOS formulation against brown-rot fungal decay.     

Manufacture of activated carbons using Egyptian wood resources and its application in oligothiophene dye adsorption

The following paper presents research on the conversion of wood wastes accessible in Egypt into activated carbon. In this study, wood samples of four Egyptian tree species were used: Delonix regia, Leucaena leucocephala, Salix mucronata, and Tipuana tipu. The wood scraps were soaked in a KOH solution and then carbonized at 600 °C under the flow of nitrogen; the resulting materials were analyzed by means of microscopic and spectroscopic techniques, low-temperature adsorption of nitrogen, and an investigation of the surface area using nitrogen sorption. The addition of a chemical activator facilitated an increase of the surface area up to 603 m² g⁻¹. In its second part, the work aims to experimentally confirm that synthesizing hybrid materials consisting of oligothiophene dye (OT) and the obtained activated carbon may contribute to improving the applicability of these carbons as dye adsorbents. Confocal microscopy, Raman spectra, and SEM-EDX microscopy were used to confirm the immobilization of oligomers on the surface of carbon hybrid materials. Confocal microscopy in particular is considered to be an appropriate technique of detecting the presence of adsorbed 6 T molecules on the carbon surface. The presented research is a major step towards the application of modified carbons as an attractive and inexpensive base for dye molecule adsorption.     

Utilization of waste tire rubber in hybrid plywood composite panel

The aim of this work was to use waste tire rubber (WTR) in the middle layer of hybrid plywood materials. The effects of four variable parameters, namely, WTR contents (430 and 720 g), resin contents (120 and 160 g/m²), hot pressing (single‐stage and two‐stage), and arrangements of veneer layers on the mechanical, physical, and acoustical properties, were studied. Beech (Fagus orientalis) and alder (Alnus glutinosa) veneers having 1.8‐mm thickness were used in the production of hybrid plywood panels. Rubber layers of 3‐ and 5‐mm thickness were used in the middle layer of plywood samples. To produce plywood panels, single‐stage and two‐stage hot‐pressing processes were used. Bonding of wood layers was performed using 120 and 160 g/m² urea‐formaldehyde resins, and to form the rubber layers and bond them to wood layers, methylene diisocyanate resin (150 g/m²) was used. Overall trend showed that with the increase in rubber content, the physical properties (water absorption, thickness swelling, and sound absorption) of the manufactured panels were improved, while the mechanical properties (modulus of rapture, modulus of elasticity, and impact strength) of the panels were reduced. Both physical and mechanical performances of plywood panels were improved with increase in resin content. An increase in the WTR content in plywood improved the composite's acoustical property. The production process of the wood/rubber plywood did not significantly affect their properties. The order of improvement in the physical properties of the panels is rubber content > resin content > arrangement of layers > pressing process. Copyright © 2015 John Wiley & Sons, Ltd.     

The improvement in interfacial shear strength of wood fiber/epoxy composite by sizing with epoxy sizing agent containing MWCNTs

This paper discloses a feasible and high efficient strategy for wood fiber treatment to introducing multi‐wall carbon nanotubes (MWCNTs) to the surface of wood fibers for the aim of improving the interfacial shear strength of wood fiber/epoxy composite. Briefly, a layer of MWCNT was deposited on wood fibers through sizing wood fibers with epoxy sizing agent containing amine‐treated MWCNTs (MWCNT‐PEI). The surface functional groups, morphology, wettability, and interphase properties of MWCNTs on the surface of wood fiber were studied. The remarkable enhancements were achieved in interfacial shear strength of reinforced composites by dipping wood fiber in MWCNTCOOH suspension and wood fiber sizing containing MWCNT‐PEI.     

Thermoplasticization of wood. II. Cyanoethylation

Cyanoethylation was attempted to convert wood into thermoplastic material as a means to utilize low quality wood species as well as wood waste materials. Cyanoethylation reaction was conducted with control of the alkalinity of the reaction media, reaction temperature and time, and wood-to-acrylonitrile ratio. Cyanoethylated wood was purified and its nitrogen content and weight gain were determined. Fourier transform infrared (FTIR) spectroscopy was used to monitor the absorption peak of cyano group. Thermoproperties of cyanoethylated wood were analyzed by means of a differential scanning calorimeter (DSC) and a dynamic mechanical thermal analyzer (DMTA). Reaction mechanisms and chemistry influencing the thermoproperties of cyanoethylated wood were discussed.     

Nanotechnology for Vasa Wood De-Acidification

The conservation of the seventeenth-century Swedish warship Vasa is a challenge due the unique history of its recovery and the delicate interventions made for its preservation. In the past years the strong acidity of wood came out as a threat for its conservation. The large amount of sulfur, produced by metabolic action of bacteria in the seabed, partly converted to sulfuric acid, catalyzes the chemical degradation of the wood through the acid hydrolysis of cellulose. This contribution reviews recent studies on the degradation of Vasa wood. We show how wood acidity can be neutralized by the application of calcium or magnesium hydroxide nanoparticles, forming an alkaline reservoir inside the wood that protect it from further acid attack. This has been evidenced by the thermal analysis carried out on fresh wood, Vasa wood, artificially degraded wood, and paper samples studied as reference cellulose-made materials. Pyrolysis temperature of cellulose was studied, as an important parameter of degradation, also related to the acidity of wood. Decreases in the pyrolysis temperature of degraded cellulose were correlated to decreases of its polymerization degree. Thermal analysis has been also used to investigate the wood de-acidification efficacy after the treatment with alkaline nanoparticles. Hydro-thermally aging, carried out on de-acidified Vasa wood samples demonstrated that de-acidification with nanoparticles facilitates protection of wood toward further acid degradation.     

Localisation and quantification of potential binding sites for compatibilisers on soft‐ and hardwood in wood–plastic composite systems

Chemical force microscopy (CFM) was used to characterise the surface of pine and beefwood with atomic force microscopy (AFM) tips coated with different compatibilisers. With the resulting force images, potential binding sites for compatibilisers, used in wood–plastic composites (WPC) to enhance adhesion between two relatively incompatible phases, were localised and quantified. Tips were coated with two commercially available polymers namely ethylene vinyl alcohol (EVOH) and polyethylene‐grafted maleic anhydride (PE‐g‐MA). It could be observed that the interaction forces between the EVOH coated tip and the wood surface was highly species sensitive, whereas adhesive forces measured between the PE‐g‐MA coated tip and the wood surface were comparable for both wood species. The force maps show that wood species differ in the distribution of functional groups, and the force histograms show that the frequency distribution of the adhesive forces varied for the two wood species. The adhesive force maps clearly show a difference between wood/compatibiliser systems, and the differences can be related to the chemical composition of the wood species. The results confirm that not all compatibilisers are equally suitable for all wood species and these results were confirmed by mechanical tensile tests of WPC systems in a related study. Copyright © 2016 John Wiley & Sons, Ltd.