二维相关红外光谱法表征2-O-甲基纤维素在离子液体Amim-Cl和Amim-(MeO)PHO2中的溶解机理

以微晶纤维素为原料合成了定向取代的2-O-甲基纤维素并制备了2种离子液体(Amim-Cl和Amim-(MeO)PHO_2),对2-O-甲基纤维素及其溶于离子液体Amim-Cl和Amim-(MeO)PHO_2的溶液进行了二维相关红外表征。通过分析2-O-甲基纤维素的氢键特征峰,揭示了不同羟基在其溶于离子液体过程中发挥的作用。研究结果表明,相较于纤维素,2-O-甲基纤维素中无2-OH…O-6氢键,仍存有分子内氢键3-OH…O-5和分子间氢键6-OH…O′-3。在2-O-甲基纤维素溶于离子液体的过程中,离子液体主要破坏的是分子间氢键6-OH…O′-3,而分子内氢键3-OH…O-5不受影响。离子液体的阴阳离子在溶解2-O-甲基纤维素的过程中均发挥了重要作用,与2-O-甲基纤维素6位羟基相互作用形成新的氢键是2-O-甲基纤维素溶于离子液体的主要动力。     

MDI和HMDI聚氨酯脲模型化合物的红外光谱研究

以二苯基甲烷-4，4′-二异氰酸酯（MDI）、二环己基甲烷二异氰酸酯（HMDI）和扩链剂乙二胺（EDA）和2，4-二氨基-3，5-二甲硫基氯苯（DDSCB，商品名TX-2）以及聚醚二元醇PTMG为原料，采用溶液法分别合成出了4种聚醚型聚氨酯脲（PUU）模型化合物，研究了其红外谱图，并对模型化合物的红外谱图进行比较。研究结果说明MDI型PUU的NH戍氢键的状态要强于HMDI型BUU，而MDI型多嵌段PUU模型化合物的羰基戍氢键的情况刚好相反，MDI型PUU的羰基与NH戍氢键状态和HMDI型PUU相比要较弱：而且酰胺Ⅲ与NH/C=O氢键有更大的关系，而酰胺Ⅱ带与醚氧／NH氢键有更大的关系；当氢键的受体只有羰基和醚氧基时，NH更易于和醚氧形成氢键。     

固体有机物合成的低温共熔溶剂的研究及其对纤维素的溶解

对固体有机物尿素、己内酰胺、乙酰胺以不同配比制备的尿素/己内酰胺、尿素/乙酰胺和乙酰胺/己内酰胺3种低温共熔溶剂进行了研究,并考察了其物理化学性质(熔点、电导率等).结果表明,随着物质的量比的不同,低共熔溶剂的熔点不同,最佳物质的量比分别为1∶3、1∶2和1∶1,在最佳物质的量比下的熔点分别为30℃、48℃和18℃.低温共熔溶剂的电导率在10-4～10-5 S/m数量级,随温度的升高,电导率增加,电导率与温度符合Arrhenius方程.IR测试结果显示,固体有机物各自分子内的氢键消失,形成了新的氢键.初步探讨了纤维素在3种体系中的溶解性能,结果显示,3种溶剂对纤维素有一定的溶解能力.通过分析得出,该类共熔体溶剂为酰胺类溶剂,主要通过其羰基上的氧原子和氨基上的氮原子与纤维素上的羟基形成氢键.IR和XRD测试结果表明,纤维素和再生纤维素有相似的结构,但纤维素的晶型从Ⅰ型转变为Ⅱ型.     

聚(苯乙烯-共-六氟-2-羟基异丙基苯乙烯)与甲基膦酸二甲酯的强氢键作用

本文用低分子模型化合物1,1,1,3,3,3-六氟-2-丙醇(HFIP)代替聚(苯乙烯-共-六氟-2-羟基异丙基苯乙烯)(PHFA),与甲基膦酸二甲酯(DMMP)等各种类型化合物形成混合物,用傅里叶变换红外光谱观察混和前后的谱图变化,发现HFIP与DMMP等含氧化合物混合时形成分子间氢键。由氢键谱带位移△v和计算所得的混合热焓△H判断这些化合物与HFIP间的氢键强弱顺序是:DMMP>四氢呋喃>二噁烷>甲乙酮>甲酸乙酯。此顺序与用反气相色谱法测得聚合物PHFA与这几种化合物之间的Folry-Huggins相互作用参数X_(12)大小顺序一致,说明PHFA强烈吸附DMMP的本质原因是二者之间存在极强的氢键作用。     

DMSO/AmimCl体系应用于微晶纤维素的制备

利用二甲基亚砜/氯化1-烯丙基-3-甲基咪唑(DMSO/AmimCl)体系通过溶解纤维素无定型区及残缺的结晶区来制备微晶纤维素。利用FT-IR、XRD、TGA和SEM等技术对微晶纤维素的结晶度、得率、结构、热稳定性能以及形态特性进行分析。研究结果表明,在DMSO/AmimCl质量比为0.4的溶剂体系中,得到的微晶纤维素性能最好,并对此实验的再现性进行了论证。FT-IR和XRD结果表明,所得微晶纤维素的化学结构以及结晶结构与商品微晶纤维素基本一致,微晶纤维素的晶型为纤维素Ⅰ型,结晶度为69.23%。TGA和SEM表明微晶纤维素的热稳定性能优异,多数纤维形态呈棒状,通常表面具有长条形凹痕。     

PTMG型热塑性聚氨酯弹性体的变温红外研究

以二苯基甲烷二异氰酸酯(MDI)、聚四氢呋喃醚二醇(PTMG)、1,4-丁二醇(BDO)为原料,无催化剂条件下制备了热塑性聚氨酯,通过红外光谱(FT-IR)、核磁共振谱(NMR)、凝胶渗透色谱(GPC)等方法表征了其结构。通过变温红外光谱研究了温度对聚氨酯中氨基甲酸酯及氢键的影响,结果发现,当温度升高时氢键开始解离,而温度降低时氢键又发生重组;当温度升高到130℃及以上时,氨基甲酸酯有极少量解离,温度降低时又重新形成氨基甲酸酯。热重分析结果表明,热塑性聚氨酯样品热稳定性较好。     

再生细菌纤维素膜的制备与性能表征

采用LiCl/DMAc的溶解体系将细菌纤维素溶解后制备再生细菌纤维素(RBC)膜,并研究了成膜的细菌纤维素溶液浓度对膜的结晶度、平衡含水率、透光率以及对营养物质(氯化钠、葡萄糖、色氨酸)的透过性能的影响。实验结果表明,随着成膜溶液浓度的升高,再生膜的结晶度有一定程度的降低;平衡含水率稍有升高;再生膜干态下的透光率变化不大但浸泡PBS后膜变化较大;对营养物质的透过系数随浓度变化较小,对葡萄糖和色氨酸的透过系数相近,约为1.0×10-6cm2/s,氯化钠的透过率系数约为2.5×10-6cm2/s。研究表明再生细菌纤维素膜是一种潜在的人工角膜板层移植材料。     

柠檬酸溶胶-凝胶法合成NiFe_2O_4纳米粉体及其电磁性能表征

以柠檬酸溶胶-凝胶自蔓延燃烧法合成了NiFe2O4纳米粉体。利用XRD技术研究了自燃烧粉体经不同温度热处理后的物相变化规律,采用SEM、TEM、IR技术对自燃烧粉体与热处理粉体进行了表征,对比研究了两者在2～18GHz内的电磁参数及损耗特性。结果表明,自燃烧粉体以NiFe2O4为主晶相,其中有少量FeNi3与α-Fe2O3杂相,随着热处理温度升高,杂相分别于600与950℃相继消失。热处理有效推动了晶界移动,实现晶粒长大。自燃烧粉体中的FeNi3相、畸变的晶体结构以及复杂的界面状况使得其较热处理样品具有特殊的红外吸收谱图与优越的电磁损耗特性。     

5-环己基-1,3,5-三嗪-2-硫酮在NH4Cl溶液中对10号钢的缓蚀行为研究

为了减缓加氢裂化过程中碳钢在氯化铵溶液中的腐蚀,开展了相关缓蚀剂的研究,以硫脲、甲醛和环己胺为原料合成了5-环己基-1,3,5-三嗪-2-硫酮,采用红外和¹H NMR对其结构进行了表征;采用失重法和电化学方法考察了其在2%NH₄Cl水溶液中对10号钢的缓蚀性能。结果表明：5-环己基-1,3,5-三嗪-2-硫酮在2%NH₄Cl溶液中对10号钢的缓蚀性能随其添加量的增加而增大,随着温度的升高而降低。电化学分析结果表明该缓蚀剂在温度较低时为混合抑制型缓蚀剂,温度升高后为阴极抑制型缓蚀剂。5-环己基-1,3,5-三嗪-2-硫酮在2%NH₄Cl溶液中与10号钢表面的吸附符合Langmuir吸附等温式,且为自发、放热过程。     

聚氨酯弹性体的高弹模量对温度的依赖性

通过动态力学分析研究了不同交联程度的聚氨酯弹性体的高弹模量对温度的依赖性。详细分析了弹性体内部的物理交联密度随温度的变化,认为物理交联密度的下降主要是氢键的解离造成的。计算得到了试样的氢键活化能和物理交联对弹性模量的贡献,同时研究了它们随温度的变化情况。交联程度小的,氢键活化能高,氢键随温度升高的解离速率快,交联程度大的则相反。     

浸渍-沉积法制备一维Au/TiO_2的光催化性能研究

以钛酸纳米管为载体、HAuCl4为金前驱体,通过浸渍-沉积法制备一维金修饰TiO2光催化剂(Au/TiO2)。通过X射线衍射和紫外-可见漫反射吸收光谱研究材料的结构和性质。以甲基橙溶液作为模拟废液,研究Au/TiO2材料在紫外光条件下的光催化活性。研究表明,由于金可以接受电子,从而促进光生电子和光生空穴的分离,使TiO2的光催化活性提高;Au/TiO2的光催化活性还与金的含量密切相关,金的最佳负载量为1%(质量分数)。     

反应注射成型(聚氨酯-聚苯乙烯)间充复合弹性体的热性能研究

通过ＤＳＣ、ＴＧ考察了反应注射成型（聚氨酯－聚苯乙烯）间充复合弹性体各相态间的相互作用及其热降解规律。结果表明，ＰＵＲ交联密度提高有利于其软段相与ＰＳ相形成部分互溶的微相结构，而ＮＣＯ／ＯＨ的提高则促进软段的微相分离及增大ＰＳ与ＰＵＲ的相容性。该共混体系的热裂解属无规热降解反应，不同热裂解温度区域内各相态的热失重均有所偏重。     

Nitrogen-doped graphene hydrogel-supported NiPt-CeO x nanocomposites and their superior catalysis for hydrogen generation from hydrazine at room temperature

The safe and efficient storage and release of hydrogen is one of the key technological challenges for the fuel cell-based hydrogen economy.Hydrazine monohydrate has attracted considerable attention as a safe and convent chemical hydrogen-storage material.Herein,we report the facile synthesis of NiPt-CeOx nanocomposites supported by three-dimensional nitrogen-doped graphene hydrogels (NGHs) via a simple one-step co-reduction synthesis method.These catalysts were composition-dependent for hydrogen generation from an alkaline solution of hydrazine.(Ni5Pt5)1-(CeOx)0.3/NGH exhibited the highest catalytic activity,with 100％ hydrogen selectivity and turnover frequencies of 408 h-1 at 298 K and 3,064 h-1 at 323 K.These superior catalytic performances are attributed to the electronic structure of the NiPt centers,which was modified by the electron interaction between NiPt and CeOx and the strong metal-support interaction between NiPt-CeOx and the NGH.     

新型储氢材料的中子衍射研究

利用高灵敏度中子粉末衍射对新型储氢材料Li2NH,LiNH2,Li4BN3H10和BH3NH3的晶体结构进行了研究.通过对中子衍射数据的拟合分析得到了材料的晶格参数,原子占位和键长等数据.研究发现测量的氢原子占位结果与X-光衍射测量的结果有明显差别.结果表明储氢材料的氧释放温度与材料中的N-H或B-H键的键长成对应关系.通过将不同的储氢材料,例如LiBH4和LiNH2,进行复合改变材料中N-H和B-H氢键的强度,可以合成新的材料,有望达到储氢的目标.     

Hansen solubility parameters for selected cellulose ether derivatives and their use in the pharmaceutical industry

The paper describes a laboratory method used for determining the partial solubility parameters of five METHOCEL^* and six ETHOCEL^* cellulose ether products. A simple computer spreadsheet has also been devised to calculate the partial solubility parameters from the laboratory data. These new laboratory derived values extend the data base of solubility parameters that have been used to explore certain cellulose ether applications. The cellulose ethers are characterized in terms of non-polar, polar, and hydrogen bonding behavior. METHOCEL A, E, F, K and J cellulose ethers all have similar solubilities and are thus assigned solubility parameters in the range of non-polar (δ d) = 17.4 - 18.2, polar (δ p) = 14.6 - 16.5, hydrogen bond (δ h) = 15.5 - 19.4 with a radius of interaction of 10.3

More organic like solubility is shown by the six ethoxy cellulose ether derivatives. The range of Hansen partial solubility parameters are non-polar (δd) 16.6 - 17.3, polar (δp) = 6.6 - 8.3, and hydrogen bond (δh) = 8.5 - 10.0.     

An FTIR spectroscopic study of hydrogen-bonding competition in entrainer-cosolvent mixtures

In chemical separation processes such as supercritical extraction the use of an entrainer cosolvent can dramatically improve selectivity and yield. Ideally, in an extraction process, an entrainer cosolvent should complex with only the desired solute, pulling it from the feed. But not all cosolvents are entrainers, and a cosolvent that is effective in one application may not be effective in others. Often, competing hydrogen bonding interactions limit the effectiveness of an entrainer cosolvent. In this paper FTIR spectroscopy is used to study hydrogen bonding competition in solute/solvent/entrainer cosolvent mixtures. The extent of hydrogen bonding is determined from analysis of hydrogen-bonded and non-hydrogen-bonded infrared absorption peaks. Since these peaks overlap, curvefitting and Fourier self-deconvolution techniques are used to resolve them. Concentrations of monomeric and hydrogen-bonded species are modeled using the associated perturbed anisotropic chain theory (APACT). Using APACT it is shown that the equilibrium constant, derived from activities, can be written as the product of a temperature-dependent term and the ratio of concentrations: K=(RT) ^vIIC _i ^vi . This gives a statistical mechanical basis for the empirical observation that for hydrogen-bonding equilibria, the ratio of concentrations is approximately equal to the ratio of activities.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Water structure near single and multi-layer nanoscopic hydrophobic plates of varying separation and interaction potentials

We have performed a series of molecular dynamics simulations of water containing two nanoscopic hydrophobic plates to investigate the modifications of the density and hydrogen bond distributions of water in the vicinity of the surfaces. Our primary goal is to look at the effects of plate thickness, solute-solvent interaction and also interplate separation on the solvent structure in the confined region between two graphite-like plates and also near the outer surfaces of the plates. The thickness of the plates is varied by considering single and triple-layer graphite plates and the interaction potential is varied by tuning the attractive strength of the 12-6 pair interaction potential between a carbon atom of the graphite plates and a water molecule. The calculations are done for four different values of the tuning parameter ranging from fully Lennard-Jones to pure repulsive pair interactions. It is found that both the solvation characteristics and hydrogen bond distributions can depend rather strongly on the strength of the attractive part of the solute-water interaction potential. The thickness of the plates, however, is found to have only minor effects on the density profiles and hydrogen bond network. This indicates that the long range electrostatic interactions between water molecules on the two opposite sides of the same plate do not make any significant contribution to the overall solvation structure of these hydrophobic plates. The solvation characteristics are primarily determined by the balance between the loss of energy due to hydrogen bond network disruption, cavity repulsion potential and offset of the same by attractive component of the solute-water interactions. Our studies with different system sizes show that the essential features of solvation properties, e.g. wetting and dewetting characteristics for different interplate separations and interaction potentials, are also present in relatively smaller systems consisting of a few hundred atoms.     

加工工艺对CPE/AO2246阻尼性能与形态结构的影响

利用氯化聚乙烯(CPE)与有机小分子2,2亚甲基-双(4-甲基-6-叔丁基苯酚)(AO2246)采用不同工艺制备了有机杂化阻尼材料,通过动态力学分析(DMA)、差示扫描量热(DSC)、扫描电镜(SEM)和红外光谱(FT-IR)考察了材料的动态力学性能和微观结构。研究结果表明,AO2246在基体CPE中的分散状态对体系的阻尼性能影响较大。在未经热压的CPE/AO2246体系中,AO2246以三维谷粒结晶存在,造成体系的损耗因子(tanδ)比基体的还要低;而经过热压工艺的CPE/AO2246体系,AO2246与CPE产生了有机杂化,使体系的tanδ峰值获得较大的提高,同时玻璃化温度向高温方向移动,改善了体系的阻尼特性。红外光谱图表明,高温热压工艺的AO2246分子间产生了氢键作用的新的吸收峰,从而进一步提高了体系的阻尼性能。     

氢化燃烧合成法制备镁基储氢合金Mg2NiH4

采用自行设计制作的反应设备，研究了氢化燃烧合成法制备Mg2NiH4的工艺参数。主要探讨了合成反应动力学因素：压力、合成温度、氢化保温时间对产物纯度的影响。实验结果表明，在初始压力为1．5MPa下，合成条件分别为：合成温度808K，合成保温时间120min，氢化保温时间60min及合成温度850K，合成保温时间60min，氢化保温时间90min时均可制备出纯的Mg2NiH4。     

Na-Ca-MMT制备介孔纤维材料的机理分析

目前市售钠基蒙脱石实际上多为钠钙基蒙脱石(Na-Ca-MMT),以此为原料制备出具有介孔结构的PVA/(Na-Ca-MMT)纤维。PVA中的O-H与MMT中的Si-O键,以及PVA中的醋酸根与MMT微粒板面上的O-H形成氢键,发生偶联作用,增强了PVA插入MMT片中的动力。通过增加MMT鳞片状微粒的层间距和改善其分散性,促使MMT在冰晶诱导下尽可能多地呈现单向排列,有利于PVA/MMT纤维的形成。对比两种Na-Ca-MMT的纤维形貌,1#样品纤维长径比大,直径均匀,可以作为制备PVA/(Na-Ca-MMT)纤维的首选原料。