微波技术在聚合反应中的研究现状

微波加热因其反应时间短、产量高、副反应少、安全等特点,使微波技术作为一种新技术在有机合成中得到广泛的应用,已成为有机合成领域的研究热点,也为聚合反应的研究提供了新的思维方法。简要介绍了微波反应器的研究进展,对国内外微波辐射在高分子聚合反应中的研究现状进行了综述,主要包括微波辅助活性可控的自由基聚合、开环聚合、逐步聚合和以离子液体为介质的聚合,并指出了微波应用于聚合反应中所需要解决的问题。     

微波辐射技术在聚合反应中的应用

综述了微波辐射技术在聚合反应中的应用,针对其在乳液聚合、溶液聚合和本体聚合中的研究进行了详细的介绍,通过与常规加热聚合反应方法的对比,发现微波辐射技术可以大大减少反应时间、有效提高反应效率,同时还具有优化产品性能、降低反应能耗等优点。微波辐射技术为聚合反应研究提供了一种新的、高效的方法。     

微波辐射在聚合反应中研究新进展

本文对微波辐射加热聚合反应的特点,及微波辐射在高分子聚合反应中的新研究进展进行了综述.     

微波辐照技术在聚合物合成方面的研究及发展

综述了微波辐照技术在聚合物合成方面的研究状况,介绍了微波技术在本体聚合、乳液和溶液聚合及功能高分子合成方面的应用。在聚合物微波固化方面,重点介绍了环氧树脂及其复合材料的微波固化,简要地介绍了其它聚合物的微波固化。最后探讨了微波技术在未来的发展趋势。     

微波辐射制备合成聚合物系列高吸水树脂研究进展

首先介绍了微波辐射聚合反应及其特点,对传统加热条件下和微波辐射条件下的自由基聚合反应进行了比较。然后就微波辐射乙烯基单体溶液聚合制备合成聚合物系列高吸水树脂的研究进展进行了综述。最后指出了微波辐射乙烯基单体聚合制备高吸水树脂研究需要关注的几个方向,即加强理论对实践的指导研究,尝试引入更多的功能性单体来改善高吸水树脂的性能,尝试采用乳液聚合、悬浮聚合等多种聚合方式等。     

酶催化聚合及酶固定化技术的研究进展

综述了酶体外催化聚合的反应机理,归纳了参与催化高分子聚合反应酶的种类以及目前关于酶的固定化技术的研究进展,并对固定化酶催化聚合的研究进行了展望。     

原子转移自由基聚合原理及应用

介绍了有关原子转移自由基聚合(ATRP)的聚合原理。最新研究表明:应用ATRP法进行聚合反应可以制备接枝聚合物、嵌段聚合物、超支化聚合物和其它有机/无机混合型聚合物等。ATRP在高分子聚合反应领域具有十分广阔的应用前景。     

自引发纯丙烯酸酯的合成及光聚合性质研究

合成了一种全新的自引发纯丙烯酸酯,利用实时红外光谱技术研究了自引发感光高分子的光聚合过程,比较了不同引发剂浓度下的聚合速率和转化率;结果表明,引入到高分子侧链的自由基引发剂仍具有较高的引发活性,双键基团也具有很好的光聚合反应活性。     

乙酸乙烯酯的微波加热聚合

对乙酸乙烯酯甲醇溶液在微波加热条件下的聚合反应进行了研究,讨论了微波聚合条件、引发剂浓度、溶剂浓度和种类对聚合产物的转化率和分子量的影响。聚合物可以在较短时间内获得。且在同样的实验条件下,用不同的溶剂获得的聚合物的分子量不同。     

利用光化学探针技术研究聚合反应过程

利用荧光探针技术研究高分子聚合反应及固化过程,简便易行而受到广泛重视。此方法的原理是在高分子的聚合或固化过程中,链的增长或交联,引起了体系结构和物理性质的巨大变化,使存在于其中的探针分子的光物理行为也相应变化。因此,通过对探针分子的监测,就可了解聚合过程的情况。在选择探针化合物时,一个基本要     

Nanohybrid polymer prepared by successive polymerization of methacrylate monomer containing silver nanoparticles in situ prepared under microwave irradiation

The well-dispersed silver nanoparticles were prepared in reactive methacrylate monomers under microwave irradiation without polymerization. In contrast to conventional heating, the synthesis of Ag nanoparticles proceeded uniformly throughout the reaction vessel only under microwave irradiation, reaching the completion of the reaction simultaneously in the whole reaction solution. Successive polymerization of the monomer containing the resulting nanoparticles has successfully produced a monohybrid of the silver nanoparticles dispersed in polymer matrix.     

Microwave-Irradiated Ring-Opening Polymerization of Octamethylcyclotetrasiloxane in the Presence of Water

α, ω-dihydroxyl polydimethylsiloxane (DHPDMS) was prepared via anionic ring-opening polymerization of octamethyl cyclotetrasiloxane (D₄) under microwave irradiation (MI) in the presence of water. The conversion and polymerization rate were calculated by the gravimetric method. The effect of microwave power on the polymerization was investigated. FTIR was used to verify the DHPDMS prepared at different irradiation times. The results show that the conversion is the highest when the initial microwave power is preset at 700 W. Compared with conventional heating (CH), the polymerization rate and equilibrium conversion are both enhanced by the introduction of microwave irradiation. The species and concentration of the cyclosiloxane mixture caused by backbiting reaction were determined by gas chromatography/mass spectrometry (GC/MS). The lower concentration of cyclosiloxane in the polymer prepared under MI indicates that side reactions have been reduced and a pure polymer obtained. The molecular weight and polydispersity index (PDI) measured by GPC show that under MI, the molecular weight of DHPDMS is lower and PDI is narrower than those under CH.     

微波在聚合物科学中的应用

综述了聚合物科学中微波应用的研究进展,讨论了微波在聚合物合成中的研究概况。也介绍了聚合物微波加工的原理及对材料结构与性能的影响,一方面微波在树脂固化中得到广泛的应用;另一方面微波在橡胶硫化中也取得了较大的成功。另外也介绍了微波在聚合物改性方面的应用。最后指出目前存在的一些问题。     

Synthesis of new polyethers derived from isoidide under phase‐transfer catalysis: Reactivity and selectivity under microwaves and classical heating

Microwave irradiation was applied to the synthesis of polyethers from 1,8‐dibromo‐ and 1,8‐dimesyl‐octane under solid–liquid phase‐transfer catalytic conditions. To evaluate the influence of microwaves on the reaction rates and polyether properties, we carried out the polymerization reactions under similar conventional conditions (oil bath) with the same temperature profiles. First, the microwave‐assisted syntheses proceeded more rapidly in comparison with conventional heating, and the reaction time was reduced from 24 h to 30 min with higher yields of polyethers. Second, the structure of the polymers strictly depended on the activation mode. Under microwave conditions, the polyethers were characterized by higher molecular weights with better homogeneity. Third, the mechanism of chain termination was different under microwave and conventional conditions. The polyethers prepared with conventional heating possessed shorter chains with mainly hydroxylated ends, whereas under microwave irradiation, the polymer chains were longer with mainly ethylenic group ends. In fact, under microwave irradiation, ethylenic group ends were formed rather rapidly and set up a hindrance to further polymer growth. In contrast, under conventional conditions terminations were essentially constituted by hydroxyl functions; however, further polymerization was terminated as well. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1255–1266, 2003     

New developments in polymer science and technology using combination of ionic liquids and microwave irradiation

The purpose of this review is to provide appropriate details concerning the application of ionic liquids (IL)s associated with microwave-assisted polymer chemistry. From the viewpoint of microwave chemistry, one of the key significant advantages of ILs is their high polarity, which is variable, depending on the cation and anion and therefore can effectively be tuned to a particular application. Hence, these liquids offer a great potential for the innovative application of microwaves for organic synthesis as well as for polymer science. ILs efficiently absorb microwave energy through an ionic conduction mechanism, and thus are employed as solvents and co-solvents, leading to a very high heating rate and a significantly shortened reaction time. Since an IL-based and microwave-accelerated procedure is efficient and environmentally benign, we believe that this method may have some potential applications in the synthesis of a wide variety of vinyl and non-vinyl polymers. This review describes application of combination of ILs with microwave irradiation as a modern tool for the addition and step-growth polymerization as well as modification of polymers and it was compared with ILs alone and conventional polymerization method.     

One-step template-free synthesis of monoporous polymer microspheres with uniform sizes via microwave-mediated dispersion polymerization

One-step facile synthesis of monoporous polymer microspheres via microwave-controlled dispersion polymerization is introduced. This template-free method employing the dispersion polymerization of styrene under microwave irradiation induces directly the formation of uniform monoporous polymer microspheres, with controllable morphologies and sizes, which can be tuned by simply adjusting parameters for the synthesis. A comparison to conventional heating indicates that microwave irradiation plays a vital role in the formation of this novel morphology.     

环状碳酸酯的合成及微波开环聚合研究

以2,2-二甲基-1,3-丙二醇和氯甲酸乙酯为原料合成了环状碳酸酯5,5-二甲基-1,3-二口恶烷-2-酮(DTC),并对DTC在食品添加剂乳酸锌引发下的微波开环聚合进行了研究.结果表明:在170 W的微波辐照下,辐照时间对聚合物的分子量有较大影响,当辐照时间为17 min时,聚合物的分子量达到最大,Mw、 Mn分别达到208 000和127 000.     

Evolution to similarity solutions for polymerization and depolymerization with microwave radiation

The kinetics of polymerization and depolymerization are critical in understanding the stability and characterization of polymers. The kinetics of simultaneous polymerization and degradation of poly(methyl methacrylate) have been investigated by varying the initiator concentration and monomer concentration under the influence of microwave energy. Microwave radiation initially polymerizes the monomer, then degrades the resulting polymer and the polymer attains an equilibrium molecular weight distribution with a polydispersity of two. To understand more fully the kinetics, the molecular weight distribution (MWD) is represented as a gamma distribution; the random degradation rate coefficient is assumed to vary linearly with molecular weight and the polymerization rate coefficient is assumed to be independent of molecular weight. The change of the MWD with time is studied by continuous distribution kinetics; the solutions obtained depict the change of the average molecular weight, polydispersity and the gamma distribution parameters with time. Experimental data indicate that reaction rates are enhanced by microwave radiation and the MWD approaches a similarity solution within 10 min for all the investigated cases. The model satisfactorily predicts the change of the MWD with time. © 2001 Society of Chemical Industry