咪唑类离子液体溶解纤维素的研究进展

综述了1-丁基-3-甲基咪唑氯盐、1-烯丙基-3-甲基咪唑氯盐、1-(2-羟乙基)-3-甲基咪唑氯盐等咪唑类离子液体对纤维素的溶解性能,咪唑类离子液体/纤维素溶液的流变性能以及咪唑类离子液体在纤维素纤维及薄膜加工中的应用;咪唑类离子液体均能较好地溶解纤维素,咪唑类离子液体/纤维素溶液均为切力变稀流体;指出选择合适的阴、...     

Time-dependent properties of epoxy resin with imidazolium ionic liquid

This study investigates creep and viscoelastic behavior of the diglycidyl ether of bisphenol A (DGEBA) epoxy resin and triethylenetetramine (TETA) system containing an imidazolium ionic liquid (IL), the 1-n-butyl-3-methylimidazolium chloride ( C ₄ MImCl ). Different time-dependent analysis methods are studied using data from tensile creep, tensile creep/recovery, and three-point and four-point flexural creep tests of epoxy with 1.0 or 4.0 phr of IL. From the results, the composition containing 1.0 phr of C ₄ MImCl , cured at 60°C, presented greater viscoelasticity and crosslink density compared to compositions cured at 30 and 40°C, which was attributed to higher free volume and higher molecular mobility induced by the presence of the IL. In tensile creep tests using the stepped isostress method (SSM), no important degrading effects were found after the addition of 1.0 phr of IL over long time periods. This composition also showed the best overall performance in flexural SSM creep tests.     

多烷基咪唑离子液体的合成及性能比较

以咪唑或1,2-二甲基咪唑和卤代烷为原料,合成了4种多烷基咪唑类离子液体,以及6种1,3-二丁基咪唑和1-丁基-3-乙基咪唑类离子液体,产率较高。产物结构经核磁共振氢谱进行了确认。测定了产物水溶液的pH和不同浓度下的电导率,研究了烷基对离子液体酸性的影响,以及不同阴离子或烷基链长度对电导率的影响。测定了产物的吸湿性,结果表明,多烷基咪唑六氟磷酸盐离子液体具有较低的吸湿性。     

三硅氧烷咪唑离子液体表面活性剂的合成与表面活性

以氯丙基甲基二甲氧基硅烷和六甲基二硅氧烷为原料,在浓硫酸催化下合成了氯丙基三硅氧烷,再与1-甲基咪唑进行季铵化反应,制备了三硅氧烷咪唑离子液体表面活性剂.用傅里叶红外光谱仪以及氢谱和碳谱核磁共振仪表征了产物的结构;并对其临界胶束浓度(cmc)及表面张力(γ)进行了测定.结果表明,与长链烷基咪唑类离子液体表面活性剂相比,三硅氧烷咪唑离子液体表面活性剂具有更好的表面活性,其cmc为15.5 mmol/L,γcmc为24.0 mN/m.     

离子液体中纤维素的均相改性及其产物性能

卤代基团比羟基具有更高的反应活性,因此将含有卤素基团的有机化合物引入到纤维素骨架上可以提高其反应活性,为其后续接枝改性提供更广的应用范围。以氯乙酰氯为酯化剂,离子液体1-丁基-3-甲基咪唑氯盐（［Bmim］Cl）为反应介质,在不加任何催化剂的情况下,直接进行纤维素的均相酯化改性。着重探讨了反应温度、反应时间、酯化剂用量等因素对反应的影响。利用红外光谱（IR）以及核磁共振（NMR）对产物结构进行表征,并研究改性后纤维素在溶剂中的溶解性能。结果表明,离子液体中纤维素的均相酯化改性的最佳工艺条件为：纤维素葡萄糖单元与氯乙酰氯的摩尔比为1∶3,反应温度为常温,反应时间为2 h。此时,改性纤维素取代度为1.36。此外,改性后,纤维素酯易溶于丙酮、二甲基亚砜、四氢呋喃等有机溶剂。     

纤维素在离子液体中均相酰化反应动力学

以离子液体1-烯丙基-3-甲基咪唑氯盐（AmimCl）为反应媒介,以微晶纤维素为原料,研究了离子液体中纤维素与酸酐均相酰化反应的动力学,通过实验考察了纤维素初始羟基浓度（0.21～0.85 mol·L^-1）及反应温度（353～373 K）对酰化反应速率的影响。结果表明,随着离子液体中纤维素羟基浓度的增大和反应温度的升高,纤维素酰化反应的速率都呈增大趋势。通过实验得到了纤维素均相酰化反应的动力学方程,纤维素乙酐酰化及乙酐、丁酐混合酸酐酰化反应的反应级数均为1,表观活化能分别为19.03 kJ·mol^-1和20.04 kJ·相似文献   

玉米秸秆纤维素在离子液体中的溶解再生研究

以玉米秸秆纤维素为原料,在离子液体1-烯丙基-3-甲基咪唑氯盐(AMIMNCI)和1-乙基-3-甲基咪唑醋酸盐(EMIMAc)中成功地制备了性能优异的再生纤维素膜材料.对再生纤维素膜进行了FTIR、SEM、WAXD和力学性能、热力学性能等表征.结果表明,AMIMCI和EMIMAc都是玉米秸秆纤维素的非衍生化优良溶剂;在溶解过程中发生了从纤维素Ⅰ到纤维素Ⅱ的晶型转变;再生秸秆纤维素膜结构均匀致密,力学性能高,在AMIMCI和EMIMAc中再生的玉米秸秆纤维素膜的力学强度分别达119 MPa和47 MPa;再生玉米秸秆纤维素膜的热力学稳定性高,初始热分解温度高于250℃.本文实际上提供了在离子液体中,从农业废弃物中生产再生纤维素材料的清洁工艺.     

A new process for dissolution of cellulose in ionic liquids

A new dissolving process (two‐step dissolving process), that is, cellulose was first swelled to the maximum in aqueous 1‐butyl‐3‐methylimidazolium chloride ([BMIM]Cl) solution, and then dissolved by stirring under vacuum to remove excessive water, was developed to prepare the cellulose/[BMIM]Cl spinning dope with high quality. The results showed that the initial water contents in [BMIM]Cl have great influence on the swelling and dissolution of cellulose, and the suitable swelling range of aqueous [BMIM]Cl solution, in which cellulose can be swollen but not dissolved, was 2–5% water content. In this range, the higher water content in aqueous [BMIM]Cl solution, the more swelling time would be taken for cellulose to reach the maximal swelling ratio. Based on these results, cellulose/[BMIM]Cl spinning dopes were prepared by using two‐step dissolving process. In the range of our experiments, cellulose spinning dopes prepared by the two‐step dissolving process had better properties, such as fewer particles, lower apparent viscosity, and higher uniformity, compared with the direct dissolving process. By using this new dissolving process, the spinning performance of cellulose/[BMIM]Cl dopes was improved, and the mechanical properties of regenerated cellulose fibers were better than those prepared by the direct dissolving process. Therefore, it is a good way to prepare cellulose/[BMIM]Cl spinning dopes by using the new dissolving process. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Catalytic oxidation of 1,3-diisopropylbenzene using imidazolium ionic liquid as catalyst

Peroxidation of alkylaromatics is the key step in the synthesis of phenols. Different imidazolium ionic liquids were investigated for the oxidation of cumene. The selectivity of cumene hydroperoxide (CHP) increased with different ionic liquids in the order [C₄mim]Cl<[C₄mim]Br<[C₄mim]BF₄<[C₄mim]OH. This finding could be interpreted as being due to the partial decomposition of CHP by the acidic proton of the imidazolium cation. Thus [C₄mim]OH was chosen as the catalyst for the oxidation of 1,3-diisopropylbenzene to corresponding hydroperoxides and its derivatives. The catalytic performance of [C₄mim]OH was also better than that of the traditional catalyst NaOH. Furthermore, the effects of the operating variables were investigated and the mechanism was discussed.     

离子液体型表面活性剂的研究进展

离子液体型表面活性剂是一种功能性离子液体,具有离子液体的特性,还具有双亲特性.简述了离子液体型表面活性剂的制备方法,在此基础上,重点综述了离子液体型表面活性剂的表面吸附、临界胶束浓度、表面张力等表面性能;同时介绍了离子液体型表面活性剂在微乳液聚合和酶催化反应中的应用,并对离子液体型表面活性剂的发展方向进行了展望.     

Study of dissolution of cellulose in ionic liquids by computer modeling

Computer modeling of the geometry and electronic structure of the solvent and its complexes with water and cellobiose allowed: explaining the decrease in the dissolving power of an ionic liquid in the presence of water using data on the electronic structure of the molecules; determining the overall mechanism of solvation of cellulose by ionic liquids and other organic solvents; calculating the change in the energy information of a solvate complex of the elementary cellulose unit with 1-butyl-3-methylimidazolium chloride, which was-20.64 kcal/mole. __________ Translated from Khimicheskie Volokna, No. 2, pp. 51–54, March–April, 2007.     

基于离子液体再生的纤维素热解特性

利用离子液体1-丁基-3-甲基咪唑氯([Bmim]Cl)溶解PH-101微晶纤维素,通过不同的再生方法获得两种再生的纤维素,并利用XRD确定其结晶度,场发射扫描电镜(SEM)获得其形貌特征,热重(TG)分析表征其热稳定性.采用Py-GC/MS 对不同结晶度纤维素进行快速热解,并对热解挥发分进行在线分析,观察结晶度对纤维素热解特性的影响.研究表明左旋葡聚糖产率随结晶度降低而减少,而小分子产物随结晶度降低而增多.     

离子液体支撑液膜的研究及应用进展

回顾了目前为止离子液体支撑液膜的制备方法、离子液体结构、支撑膜结构对离子液体支撑液膜稳定性的影响因素,介绍了其在有机物分离、气体分离、分离反应耦合方面的应用。由于传统的单元操作很难满足污染和对过程集成的要求,对离子液体支撑液膜在未来实现清洁生产的发展方向进行了展望。     

咪唑类离子液体在微环境中形成聚集体的研究进展

综述了近年来咪唑类离子液体在微环境中形成聚集体的研究进展,包括微乳液、胶束、液晶、囊泡等,展望了含离子液体聚集体的发展趋势.     

负载型离子液体催化剂中离子液体的溶剂效应研究进展

针对负载离子液体催化剂中离子液体的溶剂效应方面的研究进行了综述,系统地介绍了离子液体作为催化活性中心的溶剂,以及利用离子液体的疏水特性调节催化活性中心周边微环境等方面的研究进展,以期指出负载型离子液体催化剂应用中离子液体作为替代溶剂时存在的问题及其未来发展趋势.     

Effect of imidazolium ionic liquid type on the properties of nitrile rubber composites

We investigated the influence of hydrophilic and hydrophobic imidazolium ionic liquids on the curing kinetic, mechanical, morphological and ionic conductivity properties of nitrile rubber composites. Two room temperature ionic liquids with a common cation—1‐ethyl‐3‐methylimidazolium thiocyanate (EMIM SCN; hydrophilic) and 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM TFSI; hydrophobic)—were used. Magnesium–aluminium layered double hydroxide (MgAl‐LDH; also known as hydrotalcite) was added to carboxylated acrylonitrile–butadiene rubber (XNBR) whereas fumed silica Aerosil 380 was used in acrylonitrile–butadiene rubber (NBR) as reinforcing fillers. NBR compounds were vulcanized with a conventional sulfur‐based crosslinking system whereas XNBR compounds were cured with MgAl‐LDH. The optimum cure time reduction and tensile properties improvement were obtained when both ionic liquids were added at 5 parts per hundred rubber (phr). The results revealed that EMIM SCN and EMIM TFSI induced an increase in the AC conductivity of nitrile rubber composites from 10^?10 to 10^?8 and to 10^?7 S cm^?1, respectively (at 15 phr ionic liquid concentration). The presence of ionic liquids in NBR slightly affected the glass transition temperature (T_g) whereas the presence of EMIM TFSI in XNBR contributed to a shift in T_g towards lower temperatures from ?23 to ?31 °C, at 15 phr loading, which can be attributed to the plasticizing behaviour of EMIM TFSI in the XNBR/MgAl‐LDH system. Dynamic mechanical analysis was also carried out and the related parameters, such as the mechanical loss factor and storage modulus, were determined. © 2013 Society of Chemical Industry     

醋酸丁酸纤维素在离子液体中的均相合成

Cellulose acetate butyrates (CAB) were homogeneously synthesized in an ionic liquid, 1-allyl-3-methyl-imidazolium chloride (AmimC1).By a sequence of first adding butyric anhydride and then acetic anhydride in the cellulose/AmimCl solutions, CAB products with the butyryl contents ranging from 33% to 47%(mass） were obtained.NMR analysis showed that among the three OH groups of the anhydroglucose unit (AGU) of the synthesized CAB, the distribution of the butyryl moieties showed a preference at the C6 position, while the partial degree of substitution of acetyl moieties at the C6 position showed the minimum values.Solubility measurement showed that CAB samples readily dissolved in the common organic solvents, such as methyl ethyl ketone, dichloromethane, and ethyl acetate.     

表面活性剂对离子液体预处理纤维素的影响

采用离子液体1-甲基-3乙基咪唑磷酸二甲酯（[MEIM][DMP]）与表面活性剂耦合处理纤维素,考察表面活性剂对于酶解的影响,并用红外光谱、X射线衍射分析其机理。结果表明[MEIM][DMP]/聚乙二醇4000（PEG4000）处理的纤维素酶解率比未处理的纤维素高78.2%,比未加表面活性剂处理的再生纤维素高6.5%。红外光谱显示有PEG4000分子特征峰出现,X射线衍射分析表明PEG4000处理再生的纤维素几乎为无定形区。因此,PEG4000参与的处理有利于进一步提高纤维素酶解率,使结晶度降低,从而酶解率提高。