氨基酸离子液体对壳聚糖溶解性能的影响

合成了一系列氨基酸类离子液体,从中筛选出对溶解壳聚糖具有良好性能的离子液体——甘氨酸盐酸盐离子液体。在常温常压下考察了该离子液体1%～10%水溶液对壳聚糖的溶解能力,溶解壳聚糖能力最大能达到6.32%(质量分数,下同)。对离子液体重复使用5次后,溶解能力没有明显下降。采用X射线衍射(XRD)和红外光谱(FT-IR)对再生的壳聚糖进行表征,结果表明,壳聚糖在溶解过程中没有发生衍生化。甘氨酸盐酸盐离子液体水溶液是壳聚糖的良溶剂。     

磷酸酯类离子液体对纤维素溶解性能的研究

采用一步法合成了两种磷酸酯类离子液体:1,3-二甲基咪唑磷酸二甲酯盐([MMIM]DMP)和1-乙基-3-甲基咪唑磷酸二乙酯盐([EMIM]DEP),并比较了它们对纤维素的溶解性能。结果表明,两种离子液体均能在一定条件下溶解纤维素,而[EMIM]DEP表现出较优的溶解能力,再生得到纤维素膜;随着溶解温度的升高,溶解时间缩短。采用红外光谱(FT-IR)、热重失重(TGA)分析、X射线衍射(XRD)、扫描电镜(SEM)等对再生前后的纤维素进行了表征。结果表明,未经活化的纤维素可直接溶于离子液体中而不发生其它衍生化反应;溶解再生后的纤维素晶型发生变化;经[EMIM]DEP溶解再生后纤维素热稳定性和聚合度下降较小,再生纤维素膜结构致密均一。     

无机盐/离子液体对再生纤维素结构与性能的影响

合成了一种离子液体1-烯丙基-3-甲基咪唑亚磷酸甲酯盐([Amim][(MeO)PHO_2]),这种离子液体能很好地溶解纤维素,并加入与其阴离子结构类似的无机盐亚磷酸氢二钠(Na_2PHO_3)组成复合溶解体系。文中研究了离子液体和复合体系对纤维素结构与性能的影响,通过对原生和再生纤维素展开红外光谱、热重分析、X射线衍射及聚合度的测试表征,结果显示再生纤维素没有发生衍生化,但热稳定性和结晶度及聚合度均比原生纤维素低,且随着复合溶解体系中Na_2PHO_3含量的增大,从中再生出来的纤维素的聚合度越高、热降解温度越高、结晶度越低。这种结果可能是由于无机盐的加入降低了离子液体对纤维素的酸降解而导致的。     

微晶纤维素在Bola型咪唑基有机硅离子液体中的溶解性能

研究了微晶纤维素在Bola型咪唑基有机硅离子液体中的溶解性能。通过偏光显微镜、傅里叶变换红外光谱、X射线衍射、扫描电子显微镜和热重分析对再生前后微晶纤维素进行了表征。结果表明,Bola型咪唑基有机硅离子液体对微晶纤维素有较好的溶解能力,且不发生其他衍生化反应。微晶纤维素开始热降解温度为320℃,而再生微晶纤维素开始热降解温度为234℃,这是再生微晶纤维素发生了晶型的变化而导致其热稳定性有所下降。     

酸性离子液体水溶液中壳聚糖的氧化降解EI北大核心CSCD

筛选出对壳聚糖溶解具有良好性能的磺酸型离子液体[MIMBS]HSO4,以该离子液体水溶液为反应介质,在均相体系中进行了壳聚糖的氧化降解反应。考察了离子液体用量、H2O2与壳聚糖单元摩尔比、反应温度和反应时间对该氧化降解反应的影响。利用黏度法测定壳聚糖的相对分子质量,采用X射线衍射和红外光谱对原料和再生壳聚糖的结构进行表征。X射线衍射分析结果表明,溶解过程中壳聚糖的晶体结构遭到破坏,结晶度下降。随着离子液体溶液浓度的增加、H2O2用量的增大、反应温度的升高以及反应时间的延长,氧化降解反应进行得更加彻底。在最佳反应条件(8%离子液体水溶液、底物摩尔比5、反应温度80℃、反应时间3 h)下,再生壳聚糖的收率为74%,其黏均相对分子质量为21.2×103。     

离子液体EmimAc对甘蔗渣的溶解脱木质素研究

研究了离子液体1-乙基-3-甲基咪唑醋酸盐(EmimAc)对甘蔗的溶解作用,考察了时间、温度以及含水量对离子液体溶解木质素性能的影响。采用FTIR、HPLC、XRD等技术对溶解残渣进行了研究。结果表明,温度70℃、溶解时间为10h时,离子液体EmimAc对甘蔗渣有最好的溶解性能,溶解率可达10.14%。水能显著降低木质素在EmimAc中的溶解性,在含水量达到20%时,溶解率仅有4.37%。HPLC分析表明,甘蔗渣中主要是木质素可溶于EmimAc中。FTIR的结果显示溶解过程中残渣内未发生衍生化反应。残渣的晶型与原料甘蔗渣一致,都是纤维素I,结晶指数由46.78%下降到37.51%。实验结果表明,离子液EmimAc能够有效的溶解甘蔗渣中的木质素,在工业上具有较好的应用前景。     

功能化离子液体对纤维素的溶解性能研究

功能化离子液体氯化1-(2-羟乙基)-3-甲基咪唑盐是纤维素的新型良溶剂,在70 ℃时微晶纤维素的溶解能力达到5%～7%.向离子液体纤维素溶液中加入去离子水可获得再生纤维素.用XRD,FT-IR和TGA对再生纤维素进行了表征,IR和XRD数据表明,功能化离子液体是纤维素的直接溶剂,但TGA数据则表明再生纤维素的热稳定性有所降低,热失重残留物有所增加.对溶解机理进行了初步讨论.     

DMSO对纤维素在咪唑型离子液体中溶解性能的影响

本文通过向传统离子液体中添加助溶剂DMSO来增强离子液体对纤维素的溶解效果。系统研究了DMSO添加量对纤维素溶解性能的影响,结果表明50℃下随着DMSO添加量的增大,纤维素的溶解程度增加,当DMSO添加量为50%时溶解效果最佳。采用电导率测试研究了DMSO与离子液体的作用机理,并通过FT-IR、XRD、TGA、SEM以及力学性能测试等方法对添加不同量DMSO溶剂溶解再生后的纤维素膜进行了分析,结果表明添加DMSO后溶剂仍为纤维素的直接溶剂,溶解再生后纤维素晶型由Ⅰ转变为Ⅱ型,并且随着DMSO添加量的增加,溶剂对纤维素分子链及结晶区的破坏能力增大,从而导致再生纤维素结晶度、抗拉强度及聚合度相对纯离子液体再生的有所降低。     

均质纤维素膜的制备及其正渗透性能研究

以纤维素(cellulose)为膜材料,离子液体1-乙基-3甲基咪唑醋酸盐(EMIMAc)为溶剂,水为非溶剂,无纺布作为支撑层,通过相转化法制备了纤维素均质膜。采用红外、X-射线衍射和扫描电子显微镜表征了膜的结构及形貌,考察了该膜的正渗透性能。结果表明:纤维素溶解再生过程中没有发生化学变化,但晶型发生了转变;当原料液为0.6 mol/L的氯化钠水溶液,汲取液为特制的营养液时,所制备的正渗透膜的水通量为3.534 L/(m2·h),截盐率达到99%以上。     

细菌纤维素在NMMO·H20中的溶解性能

研究了细菌纤维素在N-甲基吗啉-N-氧化物的一水合物(NMMO·H2O)中的溶解性能,通过偏光显微分析(PM)、红外光谱分析(FT-IR)、X射线衍射分析(XRD)、热重分析(TG)等手段,表征了该溶剂体系获得的再生细菌纤维素膜的结构和性能.结果表明,该溶剂体系对细菌纤维素有良好的溶解性能,溶解过程以物理变化为主,溶解...     

N-烯丙基吡啶氯盐离子液体/有机溶液复合溶剂对纤维素的溶解性能

采用一步法合成N-烯丙基吡啶氯盐离子液体([APy]Cl),用红外光谱(FT-IR)和核磁共振(1H-NMR)进行结构表征,并与常用有机溶液(二甲基亚砜(DMSO)、N,N-二甲基甲酰胺(DMF)、N,N-二甲基乙酰胺(DMAc)及吡啶)配成复合溶剂,测定并比较对棉浆粕的溶解能力。结果表明,四种复合溶剂均为纤维素的优良溶剂,其中在[APy]Cl/DMAc复合溶剂中溶解性能最佳,在100℃、DMAc质量分数为40%时,溶解度能达到12.25%。利用FT-IR、X射线衍射(XRD)和热重分析(TGA)对溶解再生前后纤维素膜的结构进行分析。结果表明,四种复合溶剂均为纤维素的直接溶剂,可将晶型由Ⅰ转变成Ⅱ,热稳定性良好。     

磁性离子液体的制备与应用研究进展

磁性离子液体是一种新型的功能化离子液体材料,具有优良的热稳定性、优异的电化学性能、良好的溶解性能以及可回收性等特性,使其在萃取分离、反应催化和复合材料等领域具有较好的应用前景。对目前合成的磁性离子液体做了概述并根据构效关系对主要的磁性离子液体进行了分类。综述了磁性离子液体的主要制备方法,主要有一步合成法、二步合成法和辅助合成法。介绍了磁性离子液体在萃取分离、反应催化及碳纳米管复合材料领域应用研究进展。最后根据磁性离子液体在合成和应用中的不足做了展望。     

Preparation of Inorganic Materials Using Ionic Liquids

Conventional synthesis of inorganic materials relies heavily on water and organic solvents. Alternatively, the synthesis of inorganic materials using, or in the presence of, ionic liquids represents a burgeoning direction in materials chemistry. Use of ionic liquids in solvent extraction and organic catalysis has been extensively studied, but their use in inorganic synthesis has just begun. Ionic liquids are a family of non‐conventional molten salts that can act as templates and precursors to inorganic materials, as well as solvents. They offer many advantages, such as negligible vapor pressures, wide liquidus ranges, good thermal stability, tunable solubility for both organic and inorganic molecules, and much synthetic flexibility. In this Review, the use of ionic liquids in the preparation of several categories of inorganic and hybrid materials (i.e., metal structures, non‐metal elements, silicas, organosilicas, metal oxides, metal chalcogenides, metal salts, open‐framework structures, ionic liquid‐functionalized materials, and supported ionic liquids) is summarized. The status quo of the research field is assessed, and some future perspectives are furnished.     

Separation of achiral and chiral analytes using polymeric surfactants with ionic liquids as modifiers in micellar electrokinetic chromatography

In this study, we report the use of ionic liquids as modifiers in the separation of achiral and chiral analytes in micellar electrokinetic chromatography. In this investigation, polymeric surfactants and ionic liquids were added to a low-conducting buffer solution. The polymeric surfactants used in this study were poly(sodium N-undecylelinic sulfate) and poly(sodium oleyl-l-leucylvalinate). The ionic liquids used in this study were chosen because of their high conductivity, hydrophobicity, and good solvating properties. Thus, it was expected that these ionic liquids would have the ability to assist in the separation of hydrophobic mixtures while maintaining adequate background current. Three analyte mixtures were separated using various buffer combinations of polymeric surfactant and ionic liquids. The ionic liquids were shown to improve the resolution and peak efficiency of the analytes while maintaining adequate background current.     

High-stability ionic liquids. A new class of stationary phases for gas chromatography

Room-temperature ionic liquids are a class of non-molecular ionic solvents with low melting points. Their properties have the potential to be especially useful as stationary phases in gas-liquid chromatography (GLC). A series of common ionic liquids were evaluated as GLC stationary phases. It was found that many of these ionic liquids suffer from low thermal stability and possess unfavorable retention behavior for some classes of molecules. Two new ionic liquids were engineered and synthesized to overcome these drawbacks. The two new ionic liquids (1-benzyl-3-methylimidazolium trifluoromethanesulfonate and 1-(4-methoxyphenyl)-3-methylimidazolium trifluoromethanesulfonate) are based on "bulky" imidazolium cations with trifluoromethanesulfonate anions. Their solvation characteristics were evaluated using the Abraham solvation parameter model and correlations made between the structure of the cation and the degree to which the ionic liquids retain certain analytes. The new ionic liquids have good thermal stability up to 260 degrees C, provide symmetrical peak shapes, and because of their broad range of solvation-type interactions, exhibit dual-nature selectivity behavior. In addition, the ionic liquid stationary phases provided different retention behavior for many analytes compared to a commercial methylphenyl polysiloxane GLC stationary phase. This difference in selectivity is due to the unique solvation characteristics of the ionic liquids and makes them very useful as dualnature GLC stationary phases.     

Modeling and thermodynamic consistency of solubility data of refrigerants in ionic liquids

Phase equilibrium data of temperature, pressure and solubility (T-P-x) of hydrofluorocarbon-type refrigerants in different types of ionic liquids over wide ranges of temperatures and pressures are modeled and tested for thermodynamic consistency. Experimental data taken from the literature for nineteen binary mixtures refrigerant + ionic liquids with a total of forty eight isothermal data sets are considered in the study. The modified Peng–Robinson equation of state proposed by Kwak and Mansoori is used for correlating the P-T-x data and a flexible thermodynamic consistency method is applied to analyze the data. Modeling is found acceptable in all cases, meaning that deviations in correlating the data are low, proving at the same time the claimed flexibility of a well-founded model that uses simple van der Waals mixing rules. Thirty eight data sets resulted to be thermodynamically consistent, nine were found to be not-fully consistent and only one set was found to be thermodynamically inconsistent.     

Kostengünstige Kreislaufwirtschaft mit PFPE-Ölen

Due to their extraordinary properties liquids based on perfluoro-polyethers (PFPE) have claimed to have a settled place in the vacum technologie. The disposal after using the liquids will be a problem because the used liquids are toxic waste. Regeneration of used PFPE express an alternative way which protecting the environment and cost cutting. The following article describes a process for the carefull regeneration of used PFPE. The regenerated product has the same technical datas like the original product. No restrictions for use are known. The several repeat of the process with the regenerated product is possible. The output of the regeneration process is more than 90 percent. The quality of the regenerated product will be controlling permanently by physical and chemical analysis.     

离子液体在催化中的应用研究进展

近年来,离子液体以其独特的优势成为催化体系研究的热点。离子液体具有良好的溶解性、较低的挥发性、可设计性和可重复使用性等特点,作为反应催化剂和溶剂,其相比于传统溶剂展现出更好的选择性和反应速率。综述了离子液体作为反应催化剂、反应溶剂、共催化剂或活性催化剂、负载型离子液体等在催化体系中的应用研究进展,并展望了离子液体在催化中的发展前景。     

Bioderived Ionic Liquids with Alkaline Metal Ions for Transient Ionics

Choline lactate, an ionic liquid composed of bioderived materials, offers an opportunity to develop biodegradable electrochemical devices. Although ionic liquids possess large potential windows, high conductivity, and are nonvolatile, they do not exhibit electrochemical characteristics such as intercalation pseudocapacitance, redox pseudocapacitance, and electrochromism. Herein, bioderived ionic liquids are developed, including metal ions, Li, Na, and Ca, to yield ionic liquid with electrochemical behavior. Differential scanning calorimetry results reveal that the ionic liquids remained in liquid state from 230.42 to 373.15 K. The conductivities of the ionic liquids with metal are lower than those of the pristine ionic liquid, whereas the capacitance change negligibly. A protocol of the Organization for Economic Co-operation and Development 301C modified MITI test (I) confirms that the pristine ionic liquid and ionic liquids with metal are readily biodegradable. Additionally, an ionic gel comprising the ionic liquid and poly(vinyl alcohol) is biodegradable. An electrochromic device is developed using an ionic liquid containing Li ions. The device successfully changes color at −2.5 V, demonstrating the intercalation of Li ions into the WO₃ crystal. The results suggest that the electrochemically active ionic liquids have potential for the development of environmentally benign devices, sustainable electronics, and bioresorbable/implantable devices.