微波控制下咪唑类离子液体的制备

以N-甲基咪唑和氯代正丁烷为原料在微波控制下合成了离子液体1-丁基-3-甲基咪唑氯盐([BMIm]Cl),对产物的结构作了红外光谱、核磁共振等分析。用该离子液体溶解纤维素,溶解度良好,并对溶解前后纤维素的结构变化、溶解机理进行了研究。     

咪唑类离子液体对微晶纤维素溶解性能的初步研究

合成了一种新的咪唑类离子液体——二氯二(3,3'-二甲基)咪唑基亚砜盐(Cl₂),并对该离子液体溶解微晶纤维素的溶解性能进行了初步研究。通过正交试验考察了不同因素对溶解性能的影响,最佳的试验条件为: 15% NaOH 溶液活化纤维素,离子液体溶解纤维素的温度为80℃,溶解时间60 min,离子液体在不含水条件下进行实验。结果表明,该离子液体对微晶纤维素具有一定的溶解性能。同时对溶解机理进行了初步讨论。     

阳离子絮凝剂在纤维素/离子液体中的均相合成

纤维素在离子液体中有良好的溶解性能形成均相体系,文中制备了1-烯丙基-3-甲基氯代咪唑[Amim]Cl离子液体,与丙烯酰胺进行接枝共聚合及阳离子化,合成不同聚合度的纤维素阳离子絮凝剂,并与LiCl/DMAc体系进行比较,探讨其絮凝性能.结果显示:纤维素在[Amim]Cl中溶解性能良好、接枝共聚反应活性较好;纤维素聚合度...     

微波辅助离子液体法对纤维素的均相改性研究

以离子液体1-丁基-3-甲基咪唑氯盐（BMIMCl）为溶剂,采用微波辐射代替常规的加热技术,对纤维素进行均相改性研究。首先进行微波辐射下纤维素在离子液体中的溶解,研究微波辐射温度和溶解时间的影响;其次进行纤维素与氯乙酰氯在微波辅助离子液体中的均相乙酰化研究,利用FT-IR、1H-NMR对聚合物进行了表征,探讨微波辐射功率、反应温度、反应时间和氯乙酰氯用量对纤维素取代度的影响。结果表明,微波加热有利于纤维素溶解和酯化,辐射时间和温度提高均会增加纤维素溶解量,酯化剂用量和微波辐射时间对反应影响较大。     

两种咪唑型离子液体对纤维素的溶解及纺丝性能的比较

以1-乙基-3-甲基咪唑醋酸盐（[EMIM]Ac）和1-丁基-3-甲基咪唑氯盐（[BMIM]CI）两种咪唑型离子液体为溶剂,研究比较了它们对纤维素的溶解性能及其溶液的纺丝加工性能。结果发现：两种离子液体均能在一定条件下溶解纤维素,但[EMIM]Ac较[BMIM]Cl对纤维素具有更低的溶解温度和更快的溶解速率。从流变分析还发现：纤维素/[EMIM]Ac溶液与纤维素/[BMIMCl溶液均为切力变稀流体,相同条件下纤维素/[EMIM]Ac溶液的黏度远低于纤维素/[BMIM]Cl溶液,使其可在相对低的温度下纺丝。此外,GPC分析结果表明：纤维素在用[EMIM]Ac溶解及纺丝过程中降解程度较小,而用[BMIM]Cl进行溶解纺丝时,降解作用则较明显。对纤维结构与力学性能的分析结果进一步表明：与相同喷头拉伸比下制得的[EMIM]Ac法再生纤维素纤维相比,[BMIM]Cl法再生纤维素纤维的聚集态结构相对较完善,结晶度与取向度更高些,从而使其力学性能也相对较好。     

离子液体中疏水改性羟乙基纤维素的合成

采用大分子反应法,将疏水性单体l-溴代十二烷(BD)接枝到羟乙基纤维素(HEC)上,对羟乙基纤维素进行疏水改性,制备了疏水改性羟乙基纤维素(HMHEC)。研究了离子液体种类、反应温度、羟乙基纤维素浓度和BD用量对HMHEC性能的影响。最佳合成条件为:HEC浓度为3%(质量分数),溶解时间1 h,溶解温度100℃,反应时间2 h,反应温度80℃,BD用量为2 mL。在1-烯丙基-2-甲基-咪唑氯盐体系中合成的HMHEC性能好于在1-丁基-2-甲基咪唑氯盐中合成的HMHEC。     

胶原在两种离子液体[BMIM]Cl和[BMIM]Ac中的溶解及再生结构比较

采用离子交换法, 以1-丁基-3-甲基氯代咪唑([BMIM]Cl)为原料合成了咪唑醋酸盐型离子液体([BMIM]Ac), 以两者为溶剂研究了胶原纤维在咪唑类离子液体中的溶解行为及再生前后的结构与热稳定性变化。结果表明, 胶原纤维在CH₃COO^-和Cl^-型离子液体中均能溶解, 但具有明显不同的溶解特性。相对[BMIM]Cl的溶解性能而言, [BMIM]Ac能够在较低的温度下获得高浓度和良好流动性的胶原溶液, 而且再生胶原的三股螺旋结构保留度更高。FTIR、UV、XRD、CD、TG分析结果表明, 胶原在咪唑离子液体中溶解前后其化学结构未发生明显变化, 而三股螺旋的保留度和热稳定性略有降低。     

离子液体[bmim]Cl对甘蔗渣中纤维素的溶解与再生

研究了利用离子液体1-丁基-3-甲基咪唑氯盐([bmim]Cl)对甘蔗渣中的纤维素直接溶解并再生,考察了温度、NaOH浓度以及溶解时间对溶解率的影响,同时分别通过FT-IR、X射线衍射及热失重对再生纤维素的结构、结晶性及热性能进行了研究。实验表明:温度80℃、NaOH浓度为1%、溶解时间为1.5 h时,离子液体[bmim]Cl对甘蔗渣有最好的溶解性,溶解率可达到48%。离子液体主要溶解甘蔗渣中的纤维素,且为非衍生化的直接溶解,再生后的纤维素结晶形态由纤维素Ⅰ变为Ⅱ,热稳定性能同纯纤维素相比有所降低。     

AmimCl离子液体对梧桐屑的溶解再生性能

考察了梧桐屑在1-烯丙基-3-甲基咪唑氯盐(AmimCl)离子液体中的溶解再生性能.通过带热台的偏光显微镜观察了梧桐屑在离子液体中的溶解过程.实验结果表明,梧桐屑在离子液体中的溶解率随溶解时间的延长、温度的升高、初始浓度降低而增大,优化实验条件可使溶解率最高达到23％.通过13C CP/MAS NMR、FT-IR、XR...     

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.     

两种咪唑类离子液体对杉木粉的溶解性能

合成了氯化1-（2-羟乙基）-3-甲基咪唑（［HeMIM］Cl）和氯化1-烯丙基-3-甲基咪唑（［AMIM］Cl）两种离子液体,并用红外和核磁谱图对其结构进行表征。以不同浓度的NaOH对杉木粉进行活化预处理,比较了这两种离子液体对活化后的杉木粉的溶解能力,并用红外光谱和X射线衍射分析了溶解前和溶解后杉木粉的化学结构与结晶结构的变化。结果表明,两种离子液体对木材中的纤维素表现出一定的溶解能力,且［HeMIM］Cl对杉木粉的溶解能力优于［AMIM］Cl,当选用浓度为25％的NaOH对杉木粉进行活化时,溶解性能最佳,且溶解后再生纤维素的结晶度变低。     

Cycloaddition of carbon dioxide to butyl glycidyl ether using imidazolium salt ionic liquid as a catalyst

The catalytic performance of imidazolium salt ionic liquids in the cycloaddition of carbon dioxide to butyl glycidyl ether (BGE) was investigated. The catalytic activity was tested with different imidazolium salt ionic liquids at 60–140 °C under 0.62–2.17 MPa of CO₂ pressure. The imidazolium salt ionic liquid with the cation of bulkier alkyl chain length and with more nucleophilic anion showed higher conversion of BGE. High carbon dioxide pressure and high reaction temperature up to 140 °C was favorable for the high reactivity of the catalyst. The presence of zinc bromide co-catalyst enhanced the reactivity of the imidazolium salt ionic liquid. Kinetic studies with a semi-batch reactor revealed that the reaction could be considered as first order with respect to the concentration of BGE, and the activation energy was estimated as 22.6 and 22.8 kJ/mol for 1-ethyl-3-methylimidazolium chloride (EMImCl) and 1-butyl-3-methylimidazolium chloride (BMImCl), respectively.     

Preparation of cellulose-based ionic porous material compatibilized with polymeric ionic liquid

Cellulose-based ionic porous material compatibilized with polymeric ionic liquid was prepared by means of templating technique using oil/ionic liquid emulsion in the presence of sorbitane monooleate. In situ polymerization of a mixture of polymerizable ionic liquids, 1-(3-acryloyloxypropyl)-3-methylimidazolium and 1-(3-acryloyloxypropyl)-3-vinylimidazolium bromides was first performed in a solution of cellulose in a solvent of an ionic liquid, 1-butyl-3-methylimidazolium chloride. The sonication of the mixture coexisting with corn oil and sorbitan monooleate, followed by the successive treatment with methanol, acetone, and hexane gave the porous material. The material thus obtained was characterized by the FT-IR, TGA, XRD, and SEM measurements. The SEM images of the material showed the morphology of the porosity with the pore sizes of around 0.15–1.3 μm accompanied with the smaller sizes of 30–70 nm.     

Progress of dissolution of cellulose with imidazolium ionic liquid

Cellulose is the most abundant renewable bio-material. Due to its hydrogen-bonded supramolecular structure,cellulose is insoluble in water and most common organic liquids,which limits its application. The emergence of ionic liquids provides a broad platform to the application of cellulose. The recent developments concerning imidazolium ionic liquids as cellulose solvents as well as the dissolution mechanism are reviewed. Ionic liquids,containing Cl^－,CH₃CHOO^－ and (MeO)RPO₂^－ anions,appear to be the most effective solvents. A series of alkyl imidazolium ionic liquids containing alkyl phosphate was prepared by a one-pot procedure. Such ionic liquids have good thermal stability and are capable of solubilizing cellulose under mild conditions. The structure of imidazolium cation has an influence on the solubility as well. Future development of imidazolium ionic liquids is discussed.     

Synthesis of water-soluble cellulose esters applying carboxylic acid imidazolides

Water-soluble, non-ionic cellulose esters with a degree of substitution in the range from 0.11 to 3.0 were synthesized homogeneously using ionic liquids (1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, and 1-allyl-3-methylimidazolium chloride) as reaction medium. Highly substituted 3,6,9-trioxadecanoic acid esters and 3,6-dioxaheptanoic acid esters of cellulose were obtained via the activation of the carboxylic acids with N,N’-carbonyldiimidazole. The products were characterized by the means of FTIR-, ¹H- and ¹³C NMR spectroscopy.     

咪唑基离子液体中纤维素基聚氨酯材料的制备

以TDI,MDI,IPDI,聚醚(N-220)和微晶纤维素为原料,在咪唑基离子液体氯化1-丁基-3-甲基咪唑中合成了系列纤维素基聚氨酯材料,并用FT-IR,TGA,XRD,SEM表征其结构与性能。TGA结果表明纤维素基聚氨酯材料具有良好的热稳定性能,以TDI,N-220,微晶纤维素为原料制备得到的材料热性能最优。XRD结果显示,聚氨酯链段的引入破坏了微晶纤维素的晶体结构,SEM照片显示,材料结构较为均一。     

Novel homogeneous gel fibers and capillaries from blend of titanium tetrabutoxide and siloxane functionalized ionic liquid

The preparation of ionogels by sol–gel processing has attracted much attention, because the final ceramic materials combine properties of both inorganic matrix (thermal and mechanical stability) and the ionic liquid (ionic conductivity). The aim of this study was to combine different imidazolium based ionic liquids (1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF₄], 1-butyl-3-methyl imidazolium tetrafluoroborate [BMIM][BF₄], 1-decyl-3-methylimidazolium tetrafluoroborate [DMIM][BF₄] and 1-methyl-3-[3′-(triethoxysilyl)propyl]imidazolium chloride MTICl) with titanium(IV) butoxide to prepare homogenous hybrid fibers through aqueous sol–gel reaction. The study showed that ionic liquid miscibility with metal alkoxide plays an important role in the preparation of homogenous fibers. Unlike simple imidazolium salts functionalized ionic liquid was dispersed homogenously in fibers, but the main advantage is derived from its chemical structure. New stable ionic liquid can be involved in sol–gel processes through ethoxy groups and as a result it associates with titanium alkoxide network by covalent bonding providing non-leaking ceramic hybrid material. Indirect and direct characterization studies of the product were carried out by energy-dispersive X-ray spectroscopy (EDX), silicon-29 nuclear magnetic resonance spectroscopy (²⁹Si NMR), scanning electron microscopy (SEM) and optical microscopies; also infrared spectra (IR) were recorded. Thermal analyses were performed by differential scanning calorimetry (DSC).