微波辐射用于聚合反应的研究进展

微波辐射在高分子化学研究领域中的应用越来越广泛 ,效果也十分明显 ,与常规加热方式相比 ,微波辐射具有缩短反应时间 ,提高反应产率 ,节省能源损耗 ,制得产物性能好等优点。近年来 ,微波辐射在聚合反应中的应用也越来越多。因此本文对微波辐射在高分子聚合反应中的应用研究进行了综述。     

微波辐射用于聚酰亚胺的研究进展

聚酰亚胺因具有优良的综合性能而得到广泛的研究.微波辐射在高分子化学研究领域中的应用越来越广泛,效果也十分明显.与常规加热方式相比,微波辐射具有内部加热、缩短反应时间、提高反应产率、节省能耗、无温度梯度、制得产物性能好等优点.近年来,微波辐射用于聚酰亚胺的研究越来越多.因此本文对微波辐射在聚酰亚胺的合成、三阶非线性光学、聚酰亚胺复合材料以及稀土-聚酰亚胺配合物等方面的应用进行了综述.     

微波法提取水蓼中总黄酮的工艺研究

研究了水蓼中总黄酮的微波提取最佳工艺。采用单因素试验和正交试验考察微波功率、乙醇浓度、微波辐射时间、料液比对水蓼中总黄酮提取率的影响,优选提取工艺。最佳工艺条件为:微波功率为520W,乙醇浓度为60%,微波辐射60s,间歇辐射3次,料液比为1g∶20mL。结果表明,微波提取具有提取率高、提取速度快等特点,用于中草药的提取应用前景广阔。     

国内外非阻燃聚丙烯基木塑复合材料的研究进展

由于聚丙烯(PP)和天然植物纤维的不相容性,木塑复合材料(WPC)的性能不是很理想,研究者对此做了很多工作,包括对天然植物纤维的预处理、添加无机粒子/纤维及相容剂等.对天然植物纤维进行预处理可以破坏纤维网状结构中的氢键,去除覆盖在纤维表面的蜡状物和油,增加纤维表面的粗糙度,提高纤维与聚合物之间的物理连接;添加无机粒子/...     

纤维素乙醇产业化

由于能发挥缓解能源紧张、减少环境污染、促进农村发展等重要作用,利用年产量巨大的植物纤维资源,生产可再生性液体替代燃料乙醇的技术受到了巨大的关注,成为工业生物技术的研究热点。酶法生产纤维素乙醇面临多种困难:纤维素原料比重轻,收集运输不便;原料结构复杂,需要深度预处理;纤维素酶系的酶解效率有待提高;半纤维素中的木糖难以发酵转化为乙醇等。经过多年研究,新技术已经取得重大进展,开始接近实用化。紧迫的社会需求正在迫使国内外政府和企业界大量投资,开展纤维素乙醇的中试研究和试生产,力求在短时期内克服上述难点,尽快实现产业化。充分利用植物纤维资源中的多种组分,联合生产乙醇和部分高值产品的生物精练技术,是实现纤维素乙醇产业化的重要突破口和必然途径。玉米芯生物精练生产乙醇和木糖相关产品的技术正在进行产业化。本文综述了纤维素乙醇产业化的研究进展并做了展望。     

纤维素乙醇产业化

由于能发挥缓解能源紧张、减少环境污染、促进农村发展等重要作用,利用年产量巨大的植物纤维资源,生产可再生性液体替代燃料乙醇的技术受到了巨大的关注,成为工业生物技术的研究热点.酶法生产纤维素乙醇面临多种困难:纤维素原料比重轻,收集运输不便;原料结构复杂,需要深度预处理;纤维素酶系的酶解效率有待提高;半纤维素中的木糖难以发酵转化为乙醇等.经过多年研究,新技术已经取得重大进展,开始接近实用化.紧迫的社会需求正在迫使国内外政府和企业界大量投资,开展纤维素乙醇的中试研究和试生产,力求在短时期内克服上述难点,尽快实现产业化.充分利用植物纤维资源中的多种组分,联合生产乙醇和部分高值产品的生物精练技术,是实现纤维素乙醇产业化的重要突破口和必然途径.玉米芯生物精练生产乙醇和木糖相关产品的技术正在进行产业化.本文综述了纤维素乙醇产业化的研究进展并做了展望.     

低温微波技术在化学研究中的应用

低温微波技术可用于降低微波反应时体系的温度,减少或消除微波辐射时速热效应带来的副反应,具有快速高效、反应均匀、安全环保等优势,在化学研究中得到了广泛关注和应用。本文介绍了低温微波技术的实现方法,综述了近年来该技术在蛋白质研究、合成反应、天然产物研究和微波化学机理研究等领域中的应用,并展望了低温微波技术的发展方向。     

纤维素乙醇产业化

由于能发挥缓解能源紧张、减少环境污染、促进农村发展等重要作用,利用年产量巨大的植物纤维资源,生产可再生性液体替代燃料乙醇的技术受到了巨大的关注,成为工业生物技术的研究热点.酶法生产纤维素乙醇面临多种困难:纤维素原料比重轻,收集运输不便;原料结构复杂,需要深度预处理;纤维素酶系的酶解效率有待提高;半纤维素中的木糖难以发酵转化为乙醇等.经过多年研究,新技术已经取得重大进展,开始接近实用化.紧迫的社会需求正在迫使国内外政府和企业界大量投资,开展纤维素乙醇的中试研究和试生产,力求在短时期内克服上述难点,尽快实现产业化.充分利用植物纤维资源中的多种组分,联合生产乙醇和部分高值产品的生物精练技术,是实现纤维素乙醇产业化的重要突破口和必然途径.玉米芯生物精练生产乙醇和木糖相关产品的技术正在进行产业化.本文综述了纤维素乙醇产业化的研究进展并做了展望.     

微波技术在生物可降解聚合物合成中的研究进展

阐述了微波合成技术及微波化学仪器的发展历史,综述了微波辐射技术在生物可降解聚合物合成中的特点和优势,并针对其在直接缩聚法、开环聚合法以及共聚合成可生物降解聚合物中的应用和研究成果做了重点介绍。研究发现微波辐射技术具有大大降低聚合反应的时间和能耗,提高反应聚合速率、收率,且具有一定选择性的特性。而作为一种新型高效的加热方式,微波辐射技术为生物可降解聚合物合成甚至更多高分子材料的合成提供了新的思路。     

固体碱在二氧化碳-甲醇法合成碳酸二甲酯反应中的作用

本文探讨了固体碱的制备和预处理等因素对于CO₂-甲醇法合成碳酸二甲酯(DMC)的影响,发现微波法所制碱性沸石等多孔材料的反应活性高于浸渍法所制样品。本文首次报道了微波辐射低压合成DMC的新方法,该法能极大地缩短反应时间并提高产物选择性。研究表明:CO₂和甲醇生成DMC的反应在热力学上是几乎不能进行的,加入固体碱的实质是提供了一条耦合的途径。     

[Amim]Cl离子液体中微波辐射加热促进稻草秸秆酸水解制备还原糖

在1-烯丙基-3-甲基咪唑氯盐([Amim]Cl)离子液体介质中,用微波辐射加热促进稻草秸秆纤维素的酸水解,探讨了微波辐射加热及离子液体对酸催化植物纤维素水解的促进作用;并对水解产物中的还原糖进行了测定,着重考察了离子液体用量、硫酸浓度、微波功率、反应温度、反应时间等因素对还原糖收率的影响.结果表明,在[Amim]Cl...     

Microwave Assisted Synthesis of Poly(ether sulfone) – An Efficient Synthetic Route to Control Polymer Chain Structure

A novel synthetic process for the efficient control over molecular weight of the poly(ether sulfone) has been studied. The application of microwave irradiation for the condensation polymerization to synthesize poly(ether sulfone) is demonstrated. Microwave assisted polymerization results in significant reduction of reaction time. Microwave based process is also feasible at lower temperature for the synthesis of poly(ether sulfone). Polymers synthesized have been characterized using NMR and FTIR spectroscopy. Polymer film morphology and surface composition have been studied using SEM and EDX. An increase in the molecular weight is observed with increasing microwave irradiation time.     

Microwave-assisted C-H bond activation: a rapid entry into functionalized heterocycles

[reaction: see text] Microwave irradiation strongly accelerates the rhodium-catalyzed intramolecular coupling of a benzimidazole C-H bond to pendant alkenes. The cyclic products were formed in moderate to excellent yields with reaction times less than 20 min. Additionally, the use of microwave irradiation allowed the reactions to be performed without any solvent purification and with minimal precautions to exclude air.     

Microwave Effects Due to Anionic or Cationic Initiators in Emulsion Polymerization Reactions

Summary: Emulsion polymerization reactions were performed under microwave irradiation and conventional heating using anionic or cationic initiators and surfactants. Microwave irradiation promoted higher reaction rates for both initiators and surfactants, in comparison with the conventional heating. The effect of high power microwave irradiation was studied using a method of cycles of heating and cooling, where rapid polymerization reactions were obtained. In the reactions with anionic initiator and surfactant, a decrease in the particle diameters was observed with microwave heating, and even smaller particles were obtained using high power microwave irradiation. Moreover, the decrease in the particle size was acompanied by an increase in the polymer molecular weight. On the other hand, these effects were not observed for reactions with cationic initiator and surfactant.     

Microwave-assisted degradation of acid orange using a conjugated polymer,polyaniline, as catalyst

Microwave-assisted photocatalytic degradation of dyes is one of the emerging technologies for waste water remediation. Microwave effectively accelerates photocatalytic degradation, when microwave electrodeless lamp (MEL) substitutes traditional UV lamp as light source. This setup can be extremely simplified if MEL and photocatalyst can be replaced by a catalyst which can work under microwave irradiation in the absence of any light source. The present work reports for the first time degradation of acid orange 7 (AO) under microwave irradiation using polyaniline (PANI) as catalyst in the absence of any UV lamp as light source. The degradation/decolourization was carried out in neutral acidic and basic media and was monitored spectrophotometrically to evaluate the ability of microwave irradiation to degrade AO. Microwave irradiation showed excellent performance as it completely decolourizes AO dye solution in 10 min. With the advantages of low cost and rapid processing, this novel catalyst is expected to gain promising application in the treatment of various dyestuff wastewaters on a large scale.     

Microwave Irradiation in Micro‐ Meso‐Fluidic Systems; Hybrid Technology has Issued the Challenge

A combination of microwave irradiation and flow chemistry has been described as a promising smart and hyphenated technology that can fuse and synergize the benefits of the techniques. The cells and tissues of all living organisms promote a huge number of bioorganic reactions that occur as flow systems and not the batch‐type conditions typically used by chemists and biotechnologists. Microwave‐assisted chemical conversion carried out in continuous flow mode with micro‐ or meso‐channel reactors can offer significant processing advantages, including improved thermal exchange, energy efficiency, safety, mixing control, a wider range of reaction conditions, repeatability and scalability as well as dramatic reductions in side‐reactions and degradations. This review will discuss relevant examples of organic synthesis and nanoparticles production performed in continuous flow mode with integrated microwave irradiation in micro‐ or mesofluidic systems.     

Microwave synthesis and thermal properties of polyacrylate derivatives containing itaconic anhydride moieties

ABSTRACT: BACKGROUND: Microwave irradiation as an alternative heat source is now a well-known method in synthetic chemistry. Microwave heating has emerged as a powerful technique to promote a variety of chemical reactions, offering reduced pollution, low cost and offer high yields together with simplicity in processing and handling. On the other hand, copolymers containing both hydrophilic and hydrophobic segments are drawing considerable attention because of their possible use in biological systems. Various copolymer compositions can produce a very large number of different arrangements, producing materials of varying chemical and physical properties. Thus, the hydrophilicity of copolymers can be modified by changing the amount of incorporated itaconic anhydride. RESULTS: A series of methyl methacrylate (MMA) and acrylamide (AA) copolymers containing itaconic anhydride (ITA) were synthesized by microwave irradiation employing a multimode reactor (Synthos 3000 Aton Paar, GmbH, 1400 W maximum magnetron) as well as conventional method. The thermal properties of the copolymers were evaluated by different techniques. Structure-thermal property correlation based on changing the itaconic anhydride ratio was demonstrated. Results revealed that the incorporation of itaconic anhydride into the polymeric backbone of all series affect the thermal stability of copolymers. In addition, the use of the microwave method offers high molecular weight copolymers which lead eventually to an increase in thermal stability. CONCLUSIONS: Microwave irradiation method showed advantages for the produced copolymers compared to that prepared by conventional method, where it can offer a copolymer in short time, high yield, more pure compounds and more thermally stable copolymers, rather than conventional method. Also, microwave irradiation method gives higher molecular weight due to prevention of the chain transfer. Moreover, as the itaconic anhydride content increases the thermal stability and Tg increase due to the decrease in the crystallinity.     

Microwave reactions under continuous flow conditions

Microwave chemistry has already impacted significantly on the everyday synthesis of organic molecules. The adoption and integration of this liberating technology has permitted a resurrection of many synthetic transformations that were previously considered too extreme in their conditions (temperatures, pressures, reaction times) to be synthetically useful. Furthermore, whole arrays of additional chemical transformations have been devised under microwave heating that allow access to more diverse chemical architectures via more expedient routes. Continuous flow processing of chemical intermediates taking advantage of the unique heating mechanism and characteristics of microwave irradiation will certainly be the next evolutionary step forward in this area. The synergistic combination afforded by the simultaneous application of these two core processing tools will enhance still further the synthetic capabilities of tomorrow's chemists. This short review aims to highlight the current developments and future potential offered by continuous flow microwave mediated synthesis.     

微波技术在催化剂制备中的应用

微波作为一种独特的加热手段在化学领域已得到广泛应用。本文综述了微波技术在催化剂的合成、活性组分的负载等方面的研究应用，重点探讨了在分子筛催化剂的合成中微波技术所表现出的优越性，对微波合成催化剂的作用机理及影响因素作了评述，并展望了微波技术在催化领域的发展前景。     

Effect of microwave irradiation on the reactivity of chloroarenes in Suzuki—Miyaura reaction

Simple catalytic systems for the Suzuki—Miyaura reaction of aryl chlorides under microwave conditions were tested. Microwave irradiation facilitated the reaction course. The catalyst, base, and solvent effect were studied and two reaction systems offered reasonable to high yields within a short time.