聚离子液体功能材料研究进展*

2015-01-30 14:07钱文静袁超郭江娜严锋苏州大学材料与化学化工学部江苏苏州215123
中国学术期刊文摘 2015年18期
关键词:纤维素

钱文静,袁超,郭江娜,严锋(苏州大学材料与化学化工学部,江苏苏州 215123)

·推荐综述·

聚离子液体功能材料研究进展*

钱文静,袁超,郭江娜,严锋
(苏州大学材料与化学化工学部,江苏苏州 215123)

1 引言

离子液体(Ionic Liquids,ILs)是由正、负离子组成的,在室温或室温附近呈现液体状态的有机熔融盐[1~3]。离子液体具有蒸汽压低、电导率高、电化学窗口宽、热稳定性好等独特的物理化学性质,已经引起学术界和工业界的兴趣与广泛关注[4~9]。

聚离子液体(Poly(ionic liquid)s)是指由离子液体单体聚合生成的,在重复单元上具有阴、阳离子基团的一类离子液体聚合物,兼具离子液体和聚合物的优良性能[10,11]。按照化学结构,聚离子液体可分为以下几类(图1):(1)聚阳离子型离子液体,即阳离子以共价键与聚合物主链相连;(2)聚阴离子型离子液体,即阴离子以共价键与聚合物主链相连;(3)两性型聚离子液体,即阳离子和阴离子都通过共价键与聚合物主链相连[5]。由于聚离子液体兼具离子液体与聚合物的优点,并且克服了离子液体的流动性,因而近年来成为高分子科学领域研究的热点之一[12~15]。

2 聚离子液体的合成

聚离子液体的合成可以通过自由基引发聚合离子液体单体的方法实现。与离子液体性质类似,人们可通过对聚离子液体的阴离子或阳离子的设计与组合,对聚离子液体进行分子结构设计,合成多种不同结构和功能的聚离子液体。目前利用咪唑盐阳离子单体聚合制备聚离子液体的研究较多。利用阴离子交换对其功能化,可以在聚合前(单体)也可以在聚合后(聚合物)进行(图2)。例如,Mecerreyes 等[1]制备并聚合了1-乙烯基-3-丁基咪唑氯化物和溴化物,并通过与(CF3SO2)2N-,等离子交换,调节聚合物的亲疏水性。Texter 等利用微乳液聚合制备了聚离子液体凝胶。通过阴离子交换,制备了具有溶剂响应性多孔聚合物材料(凝胶)[16]。

近年来,可控活性原子转移自由基聚合(ATRP)和可逆加成-断裂链转移(RAFT)聚合、开环易位聚合(ROMP)、原位聚合、环化聚合、脱氢偶联聚合等现代聚合方法也被初步引入用于合成聚离子液体[10,13,17~19]。

3 聚离子液体的性质与应用

与非离子型聚合物相比,聚离子液体通常具有优异的离子导电性、化学稳定性、不易燃烧等特性。由于阳(阴)离子基团被“固定”在聚合物主链上,较之于离子液体,玻璃化转变温度随之升高,离子流动性相应降低,导致其粘度增大、电导率下降[13]。例如,离子液体的电导率通常在1×10-2S·cm-1左右,而聚离子液体的电导率往往低于1×10-6S·cm-1[20]。增加聚离子液体电导率的方法主要有两种:(1)增加载体离子的浓度;(2)改变电解液的结构来增加离子流动性[21]。一般说来,聚阳离子型离子液体的离子导电性低于聚阴离子型离子液体[22]。

聚离子液体这些特性使得其在(准)固态电解质、燃料电池聚电解质膜、刺激响应材料、碳材料、电化学和催化等领域得到初步应用,并展示了广泛的应用前景。

3.1(准)固态电解质材料

由于聚合物可以在液体电解质中形成三维网络结构,使液体电解质在凝胶网络中进行固化,从而失去宏观上的流动性。因此,较之于液态电解质,基于(准)固态电解质的电化学器件具有难泄漏、安全性好的优势,更接近实际应用。另外,聚合物(准)固态电解质可以配合电极材料制备成任意的形状,符合外观多样性设计的需要,有利于电化学器件向小型化、超薄型化、柔性化方向发展。2003年,Ohno等[23]合成了聚离子液体电解质材料,研究了咪唑阳离子的位置,空间结构和阴离子种类对其电导率的影响,从而使得聚离子液体(准)固态电解质的研究引起人们的关注。聚离子液体型的(准)固态电解质由于兼具聚合物的机械性能与可加工性,以及电导率高的优势,成为制备(准)固态电解质的理想材料。

严锋课题组制备了完全不含传统有机溶剂的离子液体/聚离子液体准固态电解质[24],电池光电转换效率达到 4.4%,并呈现出优良的电池稳定性。将离子液体表面修饰的TiO2纳米粒子引入离子液体/聚离子液体准固态电解质中,电池光电转换效率可以被进一步提升到5.26%。进一步的工作又设计合成了双咪唑盐阳离子聚离子液体和单咪唑盐阳离子聚离子液体(图3),制备了高效且不含有机溶剂的凝胶电解质。对电解质的电导率和I3-/I-扩散系数进行了测定,双咪唑盐阳离子聚离子液体比单咪唑阳离子液体的电导率和扩散系数要高,接近于离子液体液态电解质。另外,咪唑环阳离子上π-π结构在电池中更有利于电荷的传输。双咪唑盐阳离子聚离子液体可以在液态离子液体中形成一种聚离子液体纳米通道,有利于I3-/I-在电解质中扩散移动,提高DSSC的性能[25]。

3.2燃料电池碱性阴离子交换膜

碱性燃料电池由于可以使用Ag、Ni等非贵金属催化剂而得到越来越多的关注。然而,目前应用较多的基于季铵盐对阴离子交换聚合物膜存在耐碱稳定性差的缺陷。因此,合成具有高电导率及优异耐碱稳定性的新型阴离子交换聚合物膜,是燃料电池工业化应用必须解决的一个难题,也在近年来得到人们越来越多的关注。

将咪唑盐离子液体单体与丙烯腈、苯乙烯通过光交联聚合的方法可以制备基于咪唑盐离子液体的碱性阴离子交换聚合物膜[26]。该阴离子交换聚合物膜显示良好的电导率,并且交联剂的引入提高了碱性阴离子交换膜的机械性能。进一步的工作合成了基于双咪唑盐离子液体的碱性阴离子交换聚合物膜当离子液体单体含量为40 wt% 时,膜的电导率能够达到10-2S/cm(90℃下),在1 mol/L KOH 溶液中(6℃)浸泡30 d后,其电导率没有明显下降,显示了良好的耐碱稳定性[27]。然而,咪唑盐阳离子上的取代基团对其耐碱性影响很大。在对一系列 C2-位上含有取代基团咪唑盐单体及其均聚物(图4)的耐碱性研究时,发现σ-π 超共轭效应对其耐碱性的影响最为明显[28]。进一步的研究工作合成了一系列N3-位含有不同取代基的咪唑盐和季铵盐聚合物并测试了其耐碱性,结果表明异丙基取代的咪唑盐阳离子比季铵盐具有更优异的耐碱稳定性[29]。

3.3刺激响应材料

刺激响应性高分子材料是智能材料中的一种,它会在外界环境因素如温度、pH、光、溶剂等刺激下,产生诸如相态、形状、表面能、反应速率、渗透速率或识别等性能物理或化学性质的变化。有些材料可同时对两种或两种以上的刺激做出响应。刺激响应性高分子材料在生物医学、药物控制释放、基因载体、纳米粒子以及纳米反应器等众多领域具有广阔的应用前景。

3.3.1温度响应性材料

双亲性聚离子液体通过自组装成形态各异的聚集体(凝胶、胶束、囊泡等),从而制备温度响应性材料。Yuan等[17]将N-异丙基丙烯酰胺通过ATRP方法成功接枝到聚离子液体纳米粒子表面,得到了温度响应和离子强度响应的粒子。在高离子强度溶液中,该NP-g-PNIPAM粒子具有较高的胶束稳定性。Xiong等[30]进一步合成了基于联咪唑离子液体的纳米凝胶(图5),该纳米粒子在甲醇中具有温敏性,在改变温度的条件下可以实现纳米凝胶和宏观凝胶间的可逆相转变。

3.3.2pH响应性材料

基于聚离子液体膜还可用于制备pH响应性材料。Zhao等将咪唑盐聚离子液体和聚丙烯酸的混合物浇筑成膜,通过和氨水或NaOH溶液反应得到纳米多孔聚离子液体薄膜。这种薄膜材料在水溶液或有机溶液中能稳定存在,具有快响应(tr=5 s,tf=12 s)和灵敏度高(2.04~2.48 nm/p H unit)等优点[31]。将离子液体单体与丙烯腈光聚成膜,得到的聚离子液体薄膜分别和甲酚红(CR)、甲基橙(MO)、溴百里酚蓝(TB)等有机染料进行阴离子交换,可以制备具有pH指示功能的响应性薄膜(图6)[32]。实验结果表明, 聚离子液体薄膜在水溶液和有机溶液中均具有良好的pH响应性,并且可以被多次重复测试利用。

3.3.3光响应性材料

偶氮化合物中的偶氮基团具有特殊的光学活性,将偶氮基团与离子液体结合,可以通过光致变色基团的光响应来可逆地调变离子液体的物理化学性质,从而拓宽离子液体的应用范围。Xie等[33]在1-乙烯基咪唑上修饰偶氮苯基团,通过自由基聚合得到具有光响应性的聚离子液体。该聚合物具有优良的光致变色(异构)性能,为光存储材料和光电材料的开发提供了理论基础。

聚离子液体的一个特性是可以通过离子交换法改变聚合物的性质,制备功能高分子材料[34]。例如,通过离子交换法将偶氮苯阴离子基团与聚离子液体相结合,得到的聚离子液体不仅具有良好的导电性还具有偶氮苯基团的光敏性能,从而拓宽了离子液体的应用范围。路庆华等通过离子交换法,合成了聚(1-乙基-4-乙烯吡啶溴)/甲基橙(MO)液晶聚合物薄膜(图 7)[35]。所制备的液晶聚合物薄膜光响应迅速,双折射数值达0.067,光诱导各向异性稳定性好,有望用于光学和液晶显示材料领域。

3.3.4溶剂响应性材料

近年来,基于环糊精超分子的聚合物得到了广泛而深入的研究。严锋等将离子液体单体(含 TFSI-)与丙烯酸共聚得到聚离子液体凝胶,在玻璃化转变温度(>Tg:78℃)以上使其发生形变(见图8),并浸泡于环糊精溶液中,由于TFSI-和环糊精发生主客体作用形成了亲水性的包合物,聚离子液体由疏水聚合物变为亲水性聚合物凝胶,形变后的凝胶通过吸收水分快速恢复其初始形态,从而显示出形状记忆效应[36]。

3.3.5氧化还原刺激响应聚合物“搭扣”

主客体作用作为一个微观结构的作用力,要实现其在宏观结构的表现则需在设计材料时考虑其宏观表现。在离子液体单体与丙烯腈、丙烯酸共聚得到聚离子液体薄膜表面分别修饰接枝上主体(β-环糊精)和客体(二茂铁)分子,可制备“搭扣”式聚离子液体薄膜(见图9)[37]。离子液体官能团的引入使得该聚合物“搭扣”还可以通过电化学氧化还原调控其贴合与分离。

3.4碳材料

纳米碳材料在电子传导能力和吸附能力等方面都具备常规材料无法比拟的优势。而多孔碳材料因具有高比表面积、高孔隙率、良好的导电性和导热性、可调控的孔径和表面性能,在催化剂、催化剂载体、超级电容器、吸附剂和气体储存等领域有广泛应用[38~41]。

离子液体由于具有室温低挥发性,较高离子电导率,良好热稳定性、较低的挥发度等特性。这些特性使离子液体成为制备碳材料理想选择。另外,由于离子液体的分子可设计性,可以制备氮、硫、磷、硼等单掺杂提供了可能。严锋等以离子液体1-甲基-3-丁基咪唑二氰胺盐为前驱体制备氮掺杂多孔碳材料,组装超级电容器电极。该超级电容器具有良好的电化学性能[42]。Yuan等[43]利用聚离子液体为前驱体,以FeCl2为催化剂,900 ℃碳化制备得高导电性、介孔石墨化碳材料(如图10所示)。该合成过程介入金属盐,催化生长厚度在5~20 nm石墨化片层状纳米结构碳材料,避免了模板剂的使用。由于聚合物骨架的非流动性,碳产率可达 29.7%,而聚离子液体中含有的杂原子,使得碳材料本身具有杂原子基团,在催化、超级电容器、锂离子电池等电化学领域具有较好的应用前景。

严锋课题组将 1-丁基-3-乙烯基咪唑溴离子液体单体按不同比例与丙烯腈共聚,在 800℃下直接碳化后即得到相应碳材料。为合成氮掺杂C/Pt纳米杂化材料,合成的共聚物可以先与铂的前驱体氯铂酸(H2PtCl6·6H2O)通过阴离子交换生成[PBA][PtCl6],碳化[PBA][PtCl6]即得到相应氮掺杂 C/Pt纳米杂化材料。由于制备的铂纳米粒子高度分散在氮掺杂的碳材料表面,及电化学表面较高的电子转移速率等因素,使得C/Pt纳米杂化材料具有增强的甲醇催化氧化反应活性和稳定性。与此同时,氮掺杂的碳材料增加了碳材料的碱性度,氮元素位点上提供了孤对电子,同时增加了吡啶类官能团对Pt的电子授予能,对氮掺杂C/Pt纳米杂化材料的甲醇催化氧化反应活性和稳定性的提高起到了重要作用[44]。

Guo等[45]以SiO2纳米粒子为模板剂,表面原位聚合接枝聚离子液体。碳化后移除模板剂,得到空心碳球。该空心碳球展示了良好的导电性,高比表面积和孔隙率。Balach 等[46]使用类似的方法制备含氮元素掺杂的空心碳球(图 10)。该碳材料用作Fe2O3纳米颗粒的负载主体应用于锂离子电池电极材料。在 0.1 A/g的充放电速率下,碳基复合材料表现了较高的可逆容量,达到1120 mAh/g。

4 结论

聚离子液体作为一种新型的聚合物,近年来成为国内外研究的热点。目前,研究热点主要集中在聚离子液体的分子设计、组成-结构-性能关系,以及功能材料的制备。随着离子液体与聚离子液体理论研究的深入及应用技术的发展,需要按照离子液体与聚离子液体产品的结构和性能的需求进行精细设计,合成更多性能优异的新型功能离子液体与聚离子液体材料,丰富其基础化学理论。虽然针对聚离子液体的研究范围已扩展到电学、光学和与生物相关的研究领域, 但聚离子液体的研究仍处于起步阶段,其潜在应用前景十分广阔。

·高被引论文摘要·

被引频次:482

离子液体研究进展

石家华,孙逊,杨春和,等

离子液体作为一类新型的环境友好的“绿色溶剂”,具有很多独特的性质,在很多领域有着诱人的应用前景。本文对离子液体的合成、结构、性能及应用等方面的研究进展进行了综述。

离子液体;合成方法;溶剂;液体提取;电化学研究

来源出版物:化学通报, 2002, 65(4): 243-250

被引频次:302

1-烯丙基,3-甲基咪唑室温离子液体的合成及其对纤维素溶解性能的初步研究

任强,武进,张军,等

摘要:随着不可再生资源(如石油、天然气、煤矿和金属矿藏等)的急剧耗竭,天然高分子的开发与利用日益引起世人的关注。纤维素作为自然界中最丰富的天然高分子材料,其开发与利用一直备受关注。但由于天然纤维素较高的结晶度和分子间和分子内存在大量的氢键,使其具有不熔化、在大多数溶剂中不溶解的特点,这成为纤维素在应用开发中的最大障碍。开发有效的纤维素溶剂体系是解决这一难题的关键。研究较多的纤维素溶剂主要有铜氨溶液、N-甲基吗啉-N-氧化物(NMMO)溶剂体系,氯化锂 二甲基乙酰胺(LiCl DMAC)溶剂体系等,而这些溶剂或多或少存在着不稳定、有毒害、不易回收、价格昂贵等缺点。开发低成本、环境友好的纤维素溶剂仍然是这一领域的发展趋势。

关键词:室温离子液体;溶解;纤维素

来源出版物:高分子通报, 2003, 6(3): 448-451

被引频次:302

绿色溶剂——离子液体的制备与应用

李汝雄,王建基

摘要:合成的离子液体已达一百多种。离子液体作为溶剂可用于分离过程、化学反应,特别是催化反应、以及电化学等方面,并已取得许多良好的实验结果。离子液体易于循环利用从而减少对环境的污染,被称为绿色溶剂。

关键词:离子液体;溶剂;催化;环境保护

来源出版物:化工进展, 2002, 21(1): 43-47

被引频次:298

室温离子液体:合成、性质及应用

赵东滨,寇元

摘要:室温离子液体是一类熔点在室温附近的熔融盐,以其熔点低、蒸气压小、电化学窗口大、酸性可调及良好的溶解度、粘度、密度等特点已经或正在电化学、有机合成、催化、分离等领域被广泛应用,并因其对环境友好吸引了工业上的兴趣。

关键词:室温离子液体;蒸气压;电化学窗口;熔融盐

来源出版物:大学化学, 2002, 17(1): 42-46

被引频次:294

离子液体的性质及其在催化反应中的应用

王均凤,张锁江,陈慧萍,等

摘要:在对离子液体的国内外研究现状综合分析的基础上,对离子液体的结构性能关系和性质变化规律进行了探讨,系统地介绍了离子液体作为溶剂或催化剂在催化反应中的应用,特别是在金属催化、生物催化、反应分离耦合方面的进展。在含微量水或无水离子液体中酶能够保持高的活性和选择性,有望在生物催化方面带来突破性进展。超临界CO2/离子液体及离子液体/水/有机相提供了一种新的反应分离耦合模式,将进一步推动绿色化学的发展。

关键词:离子液体;绿色溶剂;性质;催化反应;超临界流体

来源出版物:过程工程学报, 2003, 3(2): 177-185

被引频次:222

离子液体的合成与应用

李汝雄,王建基

摘要:离子液体即在常温及附近温度下为液体的离子物质,已合成的离子液体已达上百种。离子液体的合成方法有复分解法和中和法,其应用研究领域有分离过程、化学反应特别是催化反应以及电化学等方面。

关键词:离子液体;合成;应用

来源出版物:化学试剂, 2001, 23(4): 211-215

被引频次:221

室温离子液体及其在催化和有机合成中的应用

顾彦龙,彭家建,乔琨,等

摘要:介绍了室温离子液体的制备、性质及其在催化和有机反应中的应用。

关键词:室温离子液体;制备;性质;应用

来源出版物:化学进展, 2003, 15(3): 222-241

被引频次:213

室温离子液体:一类新型的软介质和功能材料

顾彦龙,石峰,邓友全

摘要:对室温离子液体作为一种新型的介质在催化、有机合成、电化学、分离分析中的应用以及作为功能材料在摩擦与润滑、敏感材料、储能和光电材料等方面的研究进展作了综述,并对离子液体研究未来的发展作了展望。

关键词:离子液体;反应介质;功能材料;绿色化学

来源出版物:科学通报, 2004, 49(6): 515-521

被引频次:188

不断壮大的离子液体家族

杨雅立,王晓化,寇元,等

摘要:本文对近10年来出现的新型离子液体进行了分类综述,并对其发展前景提出了一些见解。

关键词:离子液体;任务专一性

来源出版物:化学进展, 2003, 15(6): 471-476

被引频次:187

功能化离子液体对纤维素的溶解性能研究

罗慧谋,李毅群,周长忍

摘要: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。

关键词:功能化离子液体;纤维素;溶解

来源出版物:高分子材料科学与工程, 2005, 21(2): 233-235

被引频次:872

来源出版物:Journal of the American Chemical Society, 2002, 124(6): 926-927

被引频次:839

Metal chlorides in ionic liquid solvents convert sugars to 5-hydroxymethylfurfural

Zhao, HB; Holladay, JE; Brown, H

Abstract: Replacing petroleum feedstocks by biomass requires efficient methods to convert carbohydrates to a variety of chemical compounds. We report the catalytic conversion of sugars giving high yield to 5-hydroxymethylfurfural (HMF), a versatile intermediate. Metal halides in 1-alkyl-3-methylimidazolium chloride are catalysts, among which chromium (II) chloride is found to be uniquely effective, leading to the conversion of glucose to HMF with a yield near 70%. A wide range of metal halides is found to catalyze the conversion of fructose to HMF. Only a negligible amount of levulinic acid is formed in these reactions.

来源出版物:Science, 2007, 316(5831): 1597-1600

被引频次:773

The phase behaviour of 1-alkyl-3-methylimidazolium tetrafluoroborates; ionic liquids and ionic liquid crystals

Holbrey, JD; Seddon, KR

Abstract: Air-and water-stable 1-alkyl-3-methylimidazolium tetrafluoroborate salts with the general formula [C-n-mim][BF4] (n=0-18) have been prepared by metathesis from the corresponding chloride or bromide salts. The salts have been characterised by H-1 NMR and IR spectroscopy, microanalysis, polarising optical microscopy and differential scanning calorimetry. Those with short alkyl chains (n=2-10) are isotropic ionic liquids at room temperature and exhibit a wide liquid range, whereas the longer chain analogues are low melting mesomorphic crystalline solids which display an enantiotropic smectic A mesophase. The thermal range of the mesophase increases with increasing chain length and in the case of the longest chain salt prepared, [C-18-mim][BF4], the mesophase range is ca. 150 degrees C.

Keywords: temperature molten-salts; clean technology; hydrogenation; solvents; cation; air

来源出版物:Journal of the Chemical Society, Dalton Transactions, 1999(13): 2133-2140

被引频次:663

Gelation of ionic liquid-based electrolytes with silica nanoparticles for quasi-solid-state dye-sensitized solar cells

Wang, P; Zakeeruddin, SM; Comte, P; et al.

Abstract: For the first time silica nanoparticles were used to solidify ionic liquids. These ionic liquid-based quasi-solid-state electrolytes were successfully employed for regenerative photoelectrochemical cells that yielded 7% efficiency at AM 1.5 sunlight in combination with an amphiphilic ruthenium polypyridyl photosensitizer.

来源出版物:Journal of the American Chemical Society, 2003, 125(5): 1166-1167

被引频次:598

1-Allyl-3-methylimidazolium chloride room temperature ionic liquid: A new and powerful nonderivatizing solvent for cellulose

Zhang, H; Wu, J; Zhang, J; et al.

Abstract: A new and highly efficient direct solvent, 1-allyl-3-methylimidazolium chloride (AMIMCI), has been used for the dissolution and regeneration of cellulose. The cellulose samples without any pretreatment were readily dissolved in AMIMCI. The regenerated cellulose materials prepared by coagulation in water exhibited a good mechanical property. Because of its thermostable and nonvolatile nature, AMIMCI was easily recycled. Therefore, a novel and nonpolluting process for the manufacture of regenerated cellulose materials using AMIMCI has been developed in this work.

Keywords: N,N-dimethylacetamide lithium-chloride; infrared-spectra; derivatives; dissolution; behavior; blends; water; regeneration

来源出版物:Macromolecules, 2005, 38(20): 8272-8277

被引频次:579

High-pressure phase behavior of ionic liquid/CO2systems

Blanchard, LA; Gu, ZY; Brennecke, JF

Abstract: This work presents the high-pressure phase behavior of CO2with six ionic liquids: 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6)], 1-n-octyl-3-methylimidazolium hexafluorophosphate ([C-8-mim][PF6]), 1-n-octyl-3-methylimidazolium tetrafluoroborate ([CB-mim][BF4]), 1-n-butpl-3-methylimidazolium nitrate ([bmim][NO3]), 1-ethyl-3-methylimidazolium ethyl sulfate([emim][EtSO4]), and N-butylpyridinium tetrafluoroborate ([N-bupy][BF4]). We explored the effect of systematically changing the anionic and cationic components of the ionic liquid on the CO2-ionic liquid phase behavior. For all of the ionic liquids tested, large quantities of CO2dissolved in the ionic liquid phase, but no appreciable amount of ionic liquid solubilized in the CO2phase. In addition, the liquid phase volume expansion with the introduction of even large amounts of CO2is negligible, in dramatic contrast to the large volume expansion observed for neutral organic liquids. Our results seek to elucidate the underlying physical mechanisms of this highly unusual phase behavior.

Keywords: carbon-dioxide; solvents; water; equilibrium; extraction; catalysis; products; CO2

来源出版物: The Journal of Physical Chemistry B, 2001, 105(12): 2437-2444

被引频次:575

Solubilities and thermodynamic properties of gases in the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate

Anthony, JL; Maginn, EJ; Brennecke, JF

Abstract: This work presents the solubility of nine different gases in 1-n-butyl-3-methylimidazolium hexafluorophosphate. The gases considered include carbon dioxide, ethylene, ethane, methane, argon, oxygen, carbon monoxide, hydrogen, and nitrogen. We also report the associated Henry's constants and enthalpies and entropies of absorption. We found carbon dioxide to have the highest solubility and strongest interactions with the ionic liquid, followed by ethylene and ethane. Argon and oxygen had very low solubilities and immeasurably weak interactions. Carbon monoxide, hydrogen, and nitrogen all had solubilities below the detection limit of our apparatus. Our results suggest that the mass transfer of gases into ionic liquids likely will be an important issue for reactions involving these gases. We also determined that ionic liquids show good potential for use as a gas-separation medium.

Keywords: equation-of-state; catalytic-hydrogenation; fluid region; temperature; pressures; solvents; water; CO2; imidazolium; argon

来源出版物:The Journal of Physical Chemistry B, 2002, 106(29): 7315-7320

被引频次:478

Properties of ionic liquid solvents for catalysis

Wilkes, JS

Abstract: Ionic liquids are good solvents for catalytic reactions. The rational selection of the appropriate ionic liquid solvent for a particular reaction requires general knowledge of the properties of ionic liquids, and the details of some properties of the specific ionic liquid solvents being considered. The solvent properties of ionic liquids that are relevant to catalysis are discussed, and sources of the values of those properties for ionic liquids are identified. A roadmap for the literature values of density, viscosity, melting and glass transition temperatures, thermal stability, empirical solvent parameters, absorption, toxicity, surface tension, heat capacity, and thermal conductivity is provided.

Keywords: density; viscosity; melting and glass transition temperatures; thermal stability empirical solvent parameters; absorption; toxicity;surface tension; heat capacity; thermal conductivity

来源出版物: Journal of Molecular Catalysis A: Chemical, 2004, 214(1): 11-17

被引频次:475

Ionic liquid crystals: hexafluorophosphate salts

Gordon, CM; Holbrey, JD; Kennedy, AR; et al.

Abstract: A series of novel hexaflurophosphate salts, based on N,N'-dialkylimidazolium and substituted N-alkylpyridinium cations, display liquid crystalline behaviour at temperatures above their melting point. The temperature range over which liquid crystalline behaviour is observed increases markedly with increasing alkyl chain length. Alkyl substitution at the 3- and 4-positions on the pyridinium ring results in a decrease in the melting point compared with the equivalent unsubstituted salt, but also leads to a large decrease in the tendency towards liquid crystalline behaviour (or mesogenicity). The salts prepared are fully characterised using a wide variety of techniques, including NMR and IR spectroscopy, DSC, and single crystal X-ray diffraction in the case of 1-dodecyl-3-methylimidazolium hexafluorophosphate. The effect of preparing mixtures containing different proportions of two cations is also reported.

Keywords: temperature molten-salts; mesogenic group; behavior; polymorphism; complexes; halides; model

来源出版物:Journal of Materials Chemistry, 1998, 8(12): 2627-2636

被引频次:468

The room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate: Electrochemical couples and physical properties

Fuller, J; Carlin, RT; Osteryoung, RA

Abstract: The room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMLBF4) was demonstrated,as a versatile electrolyte by examining three representative electrochemical couples: ferrocene and tetrathiafulvalene oxidations and lithium ion reduction. Square-wave voltammetric data for ferrocene oxidation were fit to a reversible one-electron process using the COOL11 algorithm to give a half-wave potential of 0.490 V vs. Al/Al(III) and a diffusion coefficient of 5.1 × 10-7cm2/s-1. The two-electron oxidation of tetrathiafulvalene was reversible and proceeded through two consecutive one-electron steps; although data collected at lower square-wave frequencies indicated a slow precipitation of the TTF+species. Lithium ion was reduced to lithium metal at a Pt electrode following the addition of water to the EMLBF4 electrolyte, whereas Lithium ion reduction at an Al wire produced-the beta-LiAl alloy. Conductivities and kinematic viscosities of EMIBF4 were measured from 20 to 100 degrees C and had values of 14 mS cm-1and 0.275 cm2/s-1, respectively, at 25 degrees C.

Keywords: kinetic-parameters; molten-salts; voltammetry

来源出版物:Journal of the Electrochemical Society, 1997, 144(11): 3881-3886

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聚离子液体功能材料研究进展

钱文静,袁超,郭江娜,等

摘要:聚离子液体(PILs)材料兼具离子液体和聚合物的性质,近年来已经在高分子化学、材料科学及能源科学等领域得到初步应用,并引起了人们广泛关注.本论文介绍了聚离子液体的合成,综述其在(准)固态电解质、燃料电池聚电解质膜、刺激响应性功能材料,以及碳材料等相关领域的研究与应用。

关键词:聚离子液体;固态电解质;功能材料;碳材料;刺激响应

来源出版物:化学学报, 2015, 73: 310-315 联系邮箱:严锋,fyan@suda.edu.cn

功能性离子液体萃取水溶液中Cu2+:实验与理论

刘梦莹, 车佳宁,吴蔚闳,等

摘要:本工作针对含硫脲基咪唑憎水功能离子液体在溶液中Cu2+萃取方面的应用及其机理进行研究。考察了萃取两相体积比、金属离子浓度、时间、无机盐 Na Cl、溶液 pH及离子液体烷基链长等因素的影响。结果表明:室温条件下,0.1 mL离子液体[CnMPSM][PF6](n=4、6、8)与5 mL 21.94 mg/L的氯化铜溶液室温条件下超声混合30 min,溶液中Cu2+的去除率即超过95%;且此类离子液体对金属离子的萃取效果顺序为:n=4≈n=6>n=8。以[HMPSM][PF6]为研究对象,发现溶液中无机盐NaCl的含量以及溶液pH对金属离子的萃取效果影响不明显。与传统离子液体[Cnbim][PF6](n=6、8)相比,硫脲基的引入使其萃取率由20%左右提高到99%,且有效避免因阳离子交换而引起水中咪唑阳离子含量增加问题。通过理论计算发现,功能离子液体对金属离子的萃取依赖于官能团中的S元素与Cu2+之间较强的静电及路易斯酸碱作用,与萃取实验中离子液体未和Cu2+发生阳离子交换作用相吻合。关键词:硫脲;离子液体;萃取;金属铜离子;计算

来源出版物:化学学报, 2015, 73: 116-125 联系邮箱:杨强,qyang@ecust.edu.cn

Lewis酸性离子液体催化合成丁二酸二异丙酯

赵地顺,葛京京,翟建华,等

摘要:采用两步法制备了9种不同的Lewis酸性离子液体,采用1H NMR、FT-IR对离子液体的结构进行了表征,并系统地考察了其对丁二酸和异丙醇酯化反应的催化性能。结果表明,离子液体随着卤化物用量增加表现出更强的酸性。其中[Bmim]Br-Fe2Cl6催化合成丁二酸二异丙酯效果良好,催化剂用量为丁二酸质量的10.0%,反应温度100℃,反应时间4 h,酸醇摩尔比为1︰5,丁二酸二异丙酯收率为88.9%,酯化率达92.7%。离子液体重复使用6次后,产品收率下降1.7%。

关键词:离子液体;Lewis酸;酯化;丁二酸二异丙酯;催化剂

来源出版物:化工学报, 2014, 65(2): 561-569 联系邮箱:赵地顺,zhao_dsh@hebust.edu.cn

离子液体[BMIM]PF6中铬的电沉积行为

玉山江·哈斯木,刘瑞泉,米红宇

摘要:以一氯丁烷、N-甲基咪唑和KPF6为原料,合成了1-丁基-3-甲基咪唑六氟磷酸盐离子液体([BMIM]PF6),用红外光谱(IR)对产物进行了结构分析。用循环伏安法测试该离子液体在85℃下的电化学窗口为4.7 V。考察了[BMIM]PF6-Cr(Ⅲ)电解液的电化学行为,结果表明,在85℃下Cr(Ⅲ)的还原过程是受扩散控制的一步还原不可逆过程,Cr(Ⅲ)的传递系数α=0.023,阴极扩散系数D0=1.142×10-6cm2/s。在85℃和-1.5 V条件下,用恒电势法在铜片上电沉积Cr(Ⅲ),并通过扫描电子显微镜(SEM)观察了铜片上镀层的表面结构,发现该镀层呈颗粒状,且颗粒的体积随沉积时间的延长而增大.X射线能量色散谱(EDS)和X射线粉末衍射(XRD)测试结果表明,该镀层为无定形的金属铬。

关键词:铬;离子液体;循环伏安;电化学窗口;电沉积

来源出版物:高等学校化学学报, 2013, 35(1): 140-145 联系邮箱:刘瑞泉,liu.rq@163.com

基于离子液体的绿色催化过程

孙剑,王金泉,王蕾,等

摘要:离子液体为构建绿色催化反应过程提供了新途径。本文简要评述了离子液体在几个代表性催化反应中的研究进展,如CO2羰基化、烷基化、酯交换、氧化、CO2加氢、共聚以及PET降解等;分析讨论了离子液体的特点和优势,如提高反应活性、降低废物排放以及简化分离等,并对离子液体催化反应的未来发展方向进行了展望。

关键词:离子液体;绿色催化;反应过程

来源出版物:中国科学:化学(中文版), 2014, 44(1): 100-113 联系邮箱:张锁江,sjzhang@home.ipe.ac.cn

功能化离子液体-MDEA复配体系吸收CO2

王占丽,徐凡,邢小林,等

摘要:采用一步法合成了两种功能化离子液体四乙铵-丙氨酸盐([N2222][Ala])和四乙铵-丝氨酸盐([N2222][Ser]),利用IR和1H NMR对其结构进行了表征,并测定了其玻璃转化温度和分解温度;同时,在40℃下分别将[N2222][Ala]和[N2222][Ser]与MDEA进行复配,考察复配后的体系对CO2吸收性能;实验结果表明,[N2222][Ala]和[N2222][Ser]的加入对MDEA吸收CO2均有不同程度的增强作用,当加入质量分数为10%时,体系对CO2吸收量分别增加了8.63%和5.40%。此外,研究了20~60℃温度范围内复配体系的密度、黏度等,并比较了吸收前后黏度的变化。

关键词:N-甲基二乙醇胺;离子液体;二氧化碳;吸收

来源出版物:化工进展, 2013, 32(2): 394-399 联系邮箱:任保增,renbz@zzu.edu.cn

胆碱类低共熔溶剂的物性及应用

张盈盈,陆小华,冯新,等

摘要:作为一种新型的离子液体,胆碱类低共熔溶剂具有相比于其他离子液体更为突出的特点,如低毒、生物可降解、价格低廉等,这些特点使得此类离子液体在绿色化学和工程化学中受到越来越多的关注。本文分析了胆碱类低共熔溶剂的凝固点、熔点、溶解度、黏度、表面张力、电导率等物性随温度、组成、水分等因素的变化及理论预测模型,并介绍了胆碱类低共熔溶剂在润滑、功能材料制备、电化学、有机合成及生物质催化转化等方面的潜在应用。最后就胆碱类低共熔溶剂研究及应用中存在的问题及难点对其前景做出展望。

关键词:胆碱;离子液体;凝固点;溶解度;黏度;表面张力;电导率

来源出版物:化学进展, 2013, 25(6): 881-892 联系邮箱:陆小华,xhlu@ njut.edu.cn

Ion structure controls ionic liquid near-surface and interfacial nanostructure

Elbourne, A; Voitchovsky, K; Warr, GG; et al.

Abstract: A unique, but unifying, feature of ionic liquids (ILs) is that they are nanostructured on the length scale of the ions; in many ILs well-defined polar and apolar domains exist and may percolate through the liquid. Near a surface the isotropic symmetry of the bulk structure is broken, resulting in different nanostructures which, until now, have only been studied indirectly. In this paper, in situ amplitude modulated atomic force microscopy (AM-AFM) has been used to resolve the 3-dimensional nanostructure of five protic ILs at and near the surface of mica. The surface and near surface structures are distinct and remarkably well-defined, but are very different from previously accepted descriptions. Interfacial nanostructure is strongly influenced by the registry between cations and the mica surface charge sites,whereas near surface nanostructure is sensitive to both cation and anion structure. Together these ILs reveal how interfacial nanostructure can be tuned through ion structure, informing “bottom-up” design and optimisation of ILs for diverse technologies including heterogeneous catalysis, lubrication, electrochemical processes, and nanofluids.

Keywords: scanning-tunneling-microscopy; atomic-force microscopy; alkyl chain-length; double-layer; physicochemical properties;molecular-dynamics; materials science; clean technology; molten-salts; temperature

来源出版物:Chemical Science, 2015, 6(1): 527-536 联系邮箱:TAtkin, R; rob.atkin@newcastle.edu.au

Rare-earth recycling using a functionalized ionic liquid for the selective dissolution and revalorization of Y2O3:Eu3+ from lamp phosphor waste

Dupont, D; Binnemans, KPoly(vinyl ester 1,2,3-triazolium)s: a new member of the poly(ionic liquid)s family

Abstract: The supply risk for certain rare-earth elements (REEs) has sparked the development of recycling schemes for end-of-life products like fluorescent lamps. In this paper a new recycling process for lamp phosphor waste is proposed based on the use of the functionalized ionic liquid betainium bis(trifluoromethylsulfonyl)imide, [Hbet][Tf2N]. This innovative method allows the selective dissolution of the valuable red phosphor Y2O3: Eu3+(YOX) without leaching the other constituents of the waste powder (other phosphors,glass particles and alumina). A selective dissolution of YOX is useful because this phosphor contains 80 wt% of the REEs although it only represents 20 wt% of the lamp phosphor waste. The proposed recycling process is a major improvement compared to currently used hydrometallurgical processes where the non-valuable halophosphate (HALO) phosphor (Sr,Ca)(10)(PO4)(6)(Cl,F)(2) : Sb3+, Mn2+is inevitably leached when attempting to dissolve YOX. Since the HALO phosphor can make up as much as 50 wt% of the lamp phosphorwaste powder, this consumes significant amounts of acid and complicates the further processing steps (e.g. solvent extraction). The dissolved yttrium and europium can be recovered by a single stripping step using a stoichiometric amount of solid oxalic acid or by contacting the ionic liquid with a hydrochloric acid solution. Both approaches regenerate the ionic liquid, but precipitation stripping with oxalic acid has the additional advantage that there is no loss of ionic liquid to the water phase and that the yttrium/europium oxalate can be calcined as such to reform the red Y2O3: Eu3+phosphor (purity>99.9 wt%), effectively closing the loop after only three process steps. The red phosphor prepared from the recycled yttrium and europium showed excellent luminescent properties. The resulting recycling process for lamp phosphor waste consumes only oxalic acid and features a selective leaching, a fast stripping and an immediate revalorization step. Combined with the mild conditions, the reusability of the ionic liquid and the fact that no additional waste water is generated, this process is a very green and efficient alternative to traditional mineral acid leaching.

Keywords: spent fluorescent lamps; solubilizing metal-oxides; of-the-art; solvent-extraction; aqueous-phase; recovery; separation; mercury;membrane; nickel

来源出版物:Green Chemistry, 2015, 17(2): 856-868 联系邮箱:Dupont, D; Koen.Binnemans@chem.kuleuven.be

Obadia, MM; Colliat-Dangus, G; Debuigne, A; et al.

Abstract: A vinyl ester monomer carrying a pendant 1,2,3-triazole group is synthesized in two steps and polymerized by cobalt-mediated radical polymerization. Subsequent alkylation with N-methyl bis[(trifluoromethyl) sulfonyl]imide affords the corresponding poly(vinyl ester 1,2,3-triazolium). This unprecedented example of poly(vinyl ester ionic liquid) exhibits an ionic conductivity of 9.2 × 10-7S cm-1at 30 degrees C.

Keywords: mediated radical polymerization; click chemistry polyaddition; ionic liquids; functionalization; versatile; polymers

来源出版物:Chemical Communications, 2015, 51(16): 3332-3335 联系邮箱:Drockenmuller, E; eric.drockenmuller@univ-lyon1.fr

1,2,3-Triazolium-Based Poly(ionic liquid)s with Enhanced Ion Conducting Properties Obtained through a Click Chemistry Polyaddition Strategy

Mudraboyina, BP; Obadia, MM; Allaoua, I; et al.

Abstract: 1,2,3-Triazolium-based poly(ionic liquid)s containing a triethylene glycol spacer were synthesized from the polyaddition of an alpha- azide-omega-alkyne monomer by copper-catalyzed azide-allcyne cycloaddition (CuAAC) followed by quaternization reactions with alkyl halides and subsequent anion exchanges with different fluorinated salts. A detailed structure-property relationship for solubility,thermal stability, and ionic conductivity was investigated by means of H-1 NMR spectroscopy, differential scanning calorimetry (DSC),thermogravinietric analysis (TGA), and broadband dielectric spectroscopy (BDS). One of these poly(ionic liquid)s with a methyl substituent and bis(trifluoromethylsulfonyl)imide anion exhibits an ionic conductivity of 2 × 10-5S cm-1at 30 degrees C, which is on par with the best PILs with side-chain charge carriers reported so far and is much higher than any previously reported ionenes. The straightforward synthesis along with the broad structural design and enhanced properties of this new class of poly(ionic liquid)s offer both fundamental and applicative perspectives.

Keywords: solid polymer electrolytes; step-growth polymerization; sensitized solar-cells; omega-alkyne monomers; 1,3-dipolar cycloadditions; poly (pyridinium salt) s; terminal alkynes; ammonium ionenes; material science; crystalline

来源出版物:Chemistry of Materials, 2014, 26(4): 1720-1726 联系邮箱:Drockenmuller, E; eric.drockenmuller@univ-lyon1.fr

Preparation of sphere-like g-C3N4/BiOI photocatalysts via a reactable ionic liquid for visible-light-driven photocatalytic degradation of pollutants

Di, J; Xia, JX; Yin, S; et al.

Abstract: Novel sphere-like g-C3N4/BiOI composite photocatalysts were prepared by a one-pot EG-assisted solvothermal process in the presence of reactable ionic liquid 1-butyl-3-methylimidazolium iodine ([Bmim]I). The nanostructured heterojunction was formed with g-C3N4covering the surface of BiOI microspheres uniformly. Multiple techniques were applied to investigate the structure, morphology and photocatalytic properties of as-prepared samples. During the reactive process, the ionic liquid acted as solvent, reactant, template and dispersing agent at the same time, leading to g-C3N4being uniformly dispersed on the sphere-like BiOI surface. Three different types of dyes rhodamine B (RhB), methylene blue (MB), methyl orange (MO) were chosen as model pollutants to evaluate the photocatalytic activity of g-C3N4/BiOI composite. The as-prepared g-C3N4/BiOI composite exhibited much higher photocatalytic activity than the pure BiOI. At the same time, colourless endocrine disrupting chemical bisphenol A (BPA) and phenols 4-chlorophenol (4-CP) were chosen to further evaluate the photocatalytic activity of g-C3N4/BiOI composite. The g-C3N4/BiOI composite also exhibited much higher photocatalytic activity than the pure BiOI, which showed a broad spectrum of photocatalytic degradation activities. The results indicated that the formed heterojunction of g-C3N4covers the BiOI microspheres contributed to improved electron-hole separation and enhancement in photocatalytic activity. A photocatalytic mechanism of g-C3N4/BiOI composites is also proposed.

Keywords: graphitic carbon nitride; selective catalytic-reduction; composite photocatalysts; enhanced activity; facile synthesis; BIOX X;C3N4; irradiation; performance; nanosheets

来源出版物:Journal of Materials Chemistry A, 2014, 2(15): 5340-5351 联系邮箱:Xia, JX; xjx@ujs.edu.cn; lhm@ujs.edu.cn

Au-ionic liquid functionalized reduced graphene oxide immunosensing platform for simultaneous electrochemical detection of multiple analytes

Liu, N; Ma, ZF

Abstract: In this work, an Au-ionic liquid functionalized reduced graphene oxide nanocomposite (IL-rGO-Au) was fabricated via the self-assembly of ionic liquid functionalized reduced graphene oxide (IL-rGO) and gold nanoparticles (AuNPs) by electrostatic interaction. The IL-rGO can be synthesized and stabilized by introducing the cations of the amine-terminated ionic liquids (IL-NH2) into the graphene oxide (GO). With the assistance of IL-NH2, AuNPs were uniformly and densely absorbed on the surfaces of the IL-rGO. The proposed IL-rGO-Au nanocomposite can be used as an immunosensing platform because it can not only facilitate the electrons transfer of the electrode surface but also provide a large accessible surface area for the immobilization of abundant antibody. To assess the performance of the IL-rGO-Au nanocomposite, a sandwich-type electrochemical immunosensor was designed for simultaneous multianalyte detection (carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) as model analytes). The chitosan (CS) coated prussian blue nanoparticles (PBNPs) or cadmium hexacyanoferrate nanoparticles (CdNPs) and loaded with AuNPs were used as distinguishable signal tags. The resulting immunosensor exhibited high selectivity and sensitivity in simultaneous determination of CEA and AFP in a single run. The linear ranges were from 0.01 to 100 ng mL-1for both CEA and AFP. The detection limits reached 0.01 ng mL-1for CEA and 0.006 ng mL-1for APP, respectively. No obvious nonspecific adsorption and cross-talk was observed during a series of analyses to detect target analytes. In addition, for the detection of clinical serum samples, it is well consistent with the data determined by the ELISA, indicating that the immunosensor provides a possible application for the simultaneous multianalyte determination of CEA and AFP in clinical diagnostics.

Keywords: au nanoparticle; ionic liquid functionalized reduced graphene oxide; electrochemical immunosensor; carcinoembryonic antigen;alpha-fetoprotein

来源出版物:Biosensors & Bioelectronics, 2014, 51: 184-190 联系邮箱:Ma, ZF; mazhanfang@cnu.edu.cn

Unexpected performance of layered sodium-ion cathode material in ionic liquid-based electrolyte

Chagas, LG ; Buchholz, D ; Wu, LM; et al.

Abstract: The electrochemical performance of Na0.45Ni0.22Co0.11Mn0.66O2in an ionic liquid-based electrolytic solutions is reported and compared with that obtained in a conventional, carbonate-based electrolyte. Even at ambient temperature, the Na-ion intercalation material reveals a much better electrochemical performance in 10 mol% NaTFSI (or 0.45 M) in PYR14FSI electrolyte than 0.5 M NaPF6 in PC electrolyte in terms of specific capacity and cycling stability. In particular, the electrodes cycled in the IL-based electrolyte combine a capacity retention of about 80% after 100 cycles with high specific capacities (about 200 mAh g-1) and high average voltage (2.7 V vs. Na/Na+), demonstrating that Na0.45Ni0.22Co0.11Mn0.66O2is a promising cathode material for sodium-ion batteries.

Keywords: sodium; cathode material; layered compound; ionic liquid-based electrolyte; sodium battery

来源出版物:Journal of Power Sources ,2014, 247: 377-383 联系邮箱:Passerini, S; stefano.passerini@uni-muenster.de

Gas-Liquid Mass-Transfer Properties in CO2Absorption System with Ionic Liquids

Zhang, X; Bao, D; Huang, Y; et al.

Abstract: The deficiency of mass-transfer properties in ionic liquids (ILs) has become a bottleneck in developing the novel IL-based CO2capture processes. In this study, the liquid-side mass-transfer coefficients (k(L)) were measured systematically in a stirred cell reactor by the decreasing pressure method at temperatures ranging from 303 to 323 K and over a wide range of IL concentrations from 0 to 100 wt %. Based on the data of kL, the kinetics of chemical absorption of CO2with mixed solvents containing 30 wt % monoethanolamine (MEA)and 0-70 wt % ILs were investigated. The k(L) in IL systems is influenced not only by the viscosity but also the molecular structures of ILs. The enhancement factors and the reaction activation energy were quantified. Considering both the mass-transfer rates and the stability of IL in CO2absorption system, the new IL-based system MEA + [bmim][NO3] + H2O is recommended.

Keywords: ionic liquids; carbon dioxide; mass-transfer coefficient; kinetics; absorption

来源出版物:AIChE Journal, 2014, 60(8): 2929-2939

Improving Hydrothermal Carbonization by Using Poly(ionic liquid)s

Zhang, PF; Yuan, JY; Fellinger, TP; et al.

Abstract: Functional carbonaceous materials with high specific surface areas and controllable structural compositions have been an appealing topic in recent years, owing to their wide applications in various fields. So far, a number of well-known synthetic methods including thermal pyrolysis of organic compounds, high-voltage-arc electricity, laser ablation, and chemical vapor deposition, have been developed for the preparation of carbon materials with different sizes, shapes, and chemical compositions. Nowadays, energy andsustainability issues are seriously considered when designing synthetic strategies. The recently rediscovered environmentally friendly and facile hydrothermal carbonization (HTC) procedure offers new perspectives, as it involves the use of renewable resources (e.g., cellulose)at low temperatures (130-250℃) in aqueous medium under self-generated pressure.] Materials prepared by this straightforward waterbased method are commonly nonporous and have unfavorably low surface areas (<20 m2g-1). To induce pore formation, both hard- and soft -templating strategies, and some other efficient techniques (such as the use of metal salts or protein additives) have been recently introduced into the HTC process. For example, a novel borax-mediated HTC method was reported to produce aerogel materials that have similarities to the traditional resorcinol-formaldehyde-based organic aerogels. Considering practical applications, HTC carbonaceous materials with not only porous nanostructures but also more specific features (e.g., heteroatom or metal nanoparticle doping) are highly desirable and of great potential, in particular for catalysis.

Keywords: hydrothermal synthesis; nanostructures; nitrogen doping; poly(ionic liquid)s; porous materials

来源出版物:Angewandte Chemie-International Edition ,2013, 52 (23): 6028-6032 联系邮箱:Wang, Y; Jiayin.Yuan@mpikg.mpg.de

Outstanding performance of activated graphene based supercapacitors in ionic liquid electrolyte from-50 to 80 degrees C

Tsai, WY; Lin, RY; Murali, S; et al.

Abstract: High specific surface area (SSA similar to 2000 m2/g) porous KOH-activated microwave exfoliated graphite oxide ('a-MEGO')electrodes have been tested in a eutectic mixture of ionic liquids (1:1 by weight or molar ratio N-methyl-N-propylpiperidinium bis(fluorosulfonyl)imide (PIP13-FSI) and N-butyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (PYR14-FSI)) as electrolyte for supercapacitor applications. By optimizing the carbon/electrolyte system, outstanding capacitive performance has been achieved with high capacitance (up to 180 F/g) and wide electrochemical window (up to 3.5 V) over a wide temperature range from -50 degrees C to 80 degrees C. This is the first demonstration of a carbon-ionic liquid system capable of delivering capacitance in excess of 100 F/g below room temperature. The excellent electrochemical response of the proposed couple shows that optimization of the carbon/electrolyte interface is of great importance for improving capacitive energy storage.

Keywords: electrochemical capacitors; activated graphene; ionic liquid mixture; wide temperature range

来源出版物:Nano Energy, 2013, 2 (3): 403-411 联系邮箱:Gogotsi, Y; Gogotsi@drexel.edu; simon@chimie.ups-tlse.fr

Improved Carrier Mobility in Few-Layer MoS2Field-Effect Transistors with Ionic-Liquid Gating

Perera, MM; Lin, MW; Chuang, HJ; et al.

Abstract: We report the fabrication of ionic liquid (IL)-gated field-effect transistors (FETs) consisting of bilayer and few-layer MoS2. Our transport measurements indicate that the electron mobility mu approximate to 60 cm2V-1s-1at 250 K in IL-gated devices exceeds significantly that of comparable back-gated devices. IL-FETs display a mobility increase from approximate to 100 cm2V-1s-1at 180 K to approximate to 220 cm2V-1s-1at 77 K in good agreement with the true channel mobility determined from four-terminal measurements,ambipolar behavior with a high ON/OFF ratio >10(7) (10(4)) for electrons (holes), and a near ideal subthreshold swing of approximate to 50 mV/dec at 250 K. We attribute the observed performance enhancement, specifically the increased carrier mobility that is limited by phonons, to the reduction of the Schottky barrier at the source and drain electrode by band bending caused by the ultrathin IL dielectric layer.

Keywords: field-effect transistor; MoS2; few-layer; electric double layer; Schottky barrier

来源出版物:ACS Nano ,2013, 7 (5): 4449-4458 联系邮箱:Zhou, ZX; zxzhou@wayne.edu

A new fragment contribution-corresponding states method for physicochemical properties prediction of ionic liquids

Ying, Huang; Haifeng, Dong; Xiangping, Zhang; et al.

Abstract: A new fragment contribution-corresponding states (FC—CS) method based on the group contribution method and the corresponding states principle is developed to predict critical properties of ionic liquids (ILs). There are 46 fragments specially classified for ILs considering the ionic features of ILs, and the corresponding fragment increments are determined using the experimental density data. The accuracy of the developed method is verified indirectly via predicting density and surface tension of ILs. The results show that the FC—CS method is reasonable with an average absolute relative deviation less than 4%. With the calculated critical properties,corresponding states heat capacity (CSHC) and corresponding states thermal conductivity (CSTC) correlations are proposed to predict heat capacity and thermal conductivity of ILs, respectively. The predicted results agreed well with the experimental data. The proposed FC—CS method and the two corresponding states correlations are important for design, simulation, and analysis of new ionic liquid processes.

Keywords: ionic liquids; fragment contribution-corresponding states method; density; heat capacity; thermal conductivity

来源出版物:AIChE Journal, 2013, 59(4): 1348-1359

编辑:王微

CO2capture by a task-specific ionic liquid

Bates, ED; Mayton, RD; Ntai, I; et al.

Reaction of 1-butyl imidazole with 3-bromopropylamine hydrobromide, followed by workup and anion exchange, yields a new room temperature ionic liquid incorporating a cation with an appended amine group. The new ionic liquid reacts reversibly with CO2,reversibly sequestering the gas as a carbamate salt. The new ionic liquid, which can be repeatedly recycled in this role, is comparable in efficiency for CO2capture to commercial amine sequestering reagents, and yet is nonvolatile and does not require water to function.

supercritical water; D-fructose; glucose; dehydration; decomposition; catalysis; mechanism; kinetics; sucrose; biomass

摘编自《化学学报》2015年73期:310~315页,图、表、参考文献已省略。

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