长链烷基季铵盐插层氧化石墨的结构变化

基于改进的Hummers法制备氧化石墨(GO),并以长链烷基季铵盐(CnTAB)对其进行插层处理;通过改变CnTAB的链长、浓度,得到系列CnTAB/GO插层复合物。采用XRD和元素分析对产物的最大底面间距及CnTAB插入量进行表征。结果表明,随着Cn TAB链长的增长、CnTAB浓度的增大,CnTAB/GO插层复合物的最大底面间距逐渐增大。CnTAB通过离子键作用和疏水键作用插入到GO层间,在GO片层上的吸附规律符合修正型(Modified)Langmuir模型,即CnTAB以单分子层吸附在GO片层上。根据CnTAB/GO插层复合物最大底面间距及CnTAB插入量的变化规律分析,得出CnTAB在GO层间的排布模式有单层平躺模式、类双层平躺模式、单层倾斜模式和单层直立模式。     

十六烷基三甲基溴化铵插层氧化石墨结构的分子模拟

利用分子模拟方法研究了十六烷基三甲基溴化铵(C₁₆TAB)分子数对C₁₆TAB/GO插层复合物的结构变化,探讨了C₁₆TAB在GO层间的排列方式,并通过实验数据进行验证.模拟结果表明,优化后GO结构模型的层间距为0.849 nm;C₁₆TAB/GO插层复合物的层间距随着C₁₆TAB分子数的增加呈5个阶梯状逐渐增大,层间距分别为1.56、1.98、2.33、2.76和3.40 nm,插层饱和时C₁₆TAB分子达到28个.实验结果显示,随着C₁₆TAB分子数的增加,C₁₆TAB/GO插层复合物的层间距逐渐增大,插层饱和时为3.40 nm,实验结果与模拟结果能够很好地吻合.C₁₆TAB在GO层间可能的排列方式为1~5层平躺排列或单层平躺、单层倾斜和单层直立,从能量和结构的角度探明了C₁₆TAB在GO层间的最优排列为1~5层平躺排列.     

十六烷基三甲基溴化铵插层氧化石墨结构的分子模拟

利用分子模拟方法研究了十六烷基三甲基溴化铵(C16TAB)分子数对C16TAB/GO插层复合物的结构变化,探讨了C16TAB在GO层间的排列方式,并通过实验数据进行验证。模拟结果表明,优化后GO结构模型的层间距为0.849 nm;C16TAB/GO插层复合物的层间距随着C16TAB分子数的增加呈5个阶梯状逐渐增大,层间距分别为1.56、1.98、2.33、2.76和3.40 nm,插层饱和时C16TAB分子达到28个。实验结果显示,随着C16TAB分子数的增加,C16TAB/GO插层复合物的层间距逐渐增大,插层饱和时为3.40 nm,实验结果与模拟结果能够很好地吻合。C16TAB在GO层间可能的排列方式为1~5层平躺排列或单层平躺、单层倾斜和单层直立,从能量和结构的角度探明了C16TAB在GO层间的最优排列为1~5层平躺排列。     

层状钨基氧化物复合材料的合成与电子特性

W₂O₆·H₂O /一元烷基胺复合物[(C_nH_2n+1NH₂，n=4、8、12、16)嵌入层状氧化钨W₂O₆·H₂O] 的XRD、IR、TG-DSC分析表明：烷基胺C_nH_2n+1NH₂能基于质子加合的机制嵌入W₂O₆·H₂O层间，且插层复合物之间烷基胺的插入与抽出是个可逆过程；烷基胺嵌入层间后以全反式构象双层排布，层间距d随烷基胺碳原子数的增加而线性增长，烷基链与层板的夹角为71.6°。插层复合物UV-Vis分析发现，各种复合物的禁带宽度相对半导体氧化钨的禁带宽度变宽了很多，这表明可以通过嵌入不同的物质来调节氧化钨层与层之间的电子传递能力。     

长链烷胺及手性钛的螯合物Ti[(OC2H4)3N][OCH(CH3)2]在层状V2O5中的插层行为

用一种简便快速方法合成了一系列长链有机胺插层V₂O₅化合物. 用粉末X射线衍射(XRD)、红外光谱(FT-IR)、漫反射紫外-可见光谱(DR UV-VIS)等手段对插层产品的结构进行了表征. 除了正十六胺插层V₂O₅产品外, 其它长链烷胺插层V₂O₅产品的层间距d₀₀₁与长链烷胺碳数n之间具有良好的线性关系: d₀₀₁＝0.160n_C＋0.731 nm. 正十六胺与V₂O₅反应后生成两个插层相, 一个相的层间距d₀₀₁为4.01 nm, 另一相的d₀₀₁为3.20 nm. 此外, 研究了手性钛的螯合物Ti[(OC₂H₄)₃N][OCH(CH₃)₂] (记为TEAIP)在V₂O₅层间的插层行为, 得到相应的插层产品.     

反离子对氟表面活性剂的影响1. 表面活性及胶团化作用

通过表面张力和荧光探针法研究了全氟辛酸钠、全氟辛酸铵以及全氟辛酸四烷基铵[C₇F₁₅COON(C_nH_2n+1)₄, n＝1, 2, 3, 4]的表面活性以及胶团化作用, 系统地讨论了各种反离子, 特别是反离子大小的影响. 结果表明, 与普通碳氢表面活性剂不同, 反离子对这类氟表面活性剂的表面活性以及胶团化作用有很大影响. 表面活性剂的临界胶束浓度(cmc)随反离子的增大而下降; 饱和吸附层中平均每个分子所占的面积则大致随反离子的增大而增大. 而表面张力的变化则较为复杂. cmc时的表面张力随反离子的增大先上升(从全氟辛酸铵到全氟辛酸四乙铵)后下降(从全氟辛酸四乙铵到全氟辛酸四丁铵). 通过反离子的空间位阻、疏水性、插入以及电荷屏蔽效应对上述结果做了解释.     

高岭石-硬脂酸插层复合物的制备及结构模型的提出

以张家口高岭土为原料,通过直接插层与取代相结合的方法制备高岭石-硬脂酸插层复合物.利用 X射线粉末衍射、红外光谱、热重及透射电子显微镜对制备产物进行表征.结果表明:硬脂酸插入到高岭石层间,高岭石层间距d₀₀₁值由0.72 nm增加到4.05~4.37 nm,插层率达到86.9%;反应时间和溶液pH值会对高岭石-硬脂酸插层复合物的层间距及插层率产生影响;甲氧基嫁接在高岭石表面,与硬脂酸分子同时存在于高岭石层间.高岭石经甲醇改性后脱羟基温度明显降低,高岭石羟基活性提高;高岭石-硬脂酸插层复合物的稳定温度在160 ℃以下.经过硬脂酸插层改性后的高岭石片层,从边缘开始出现卷曲现象,并且部分长条状片层形成类似埃洛石相的纳米卷;对硬脂酸插层高岭石的作用机理进行分析,结合结构计算,提出高岭石-硬脂酸插层复合物的结构模型,该模型可以解释高岭石-硬脂酸插层复合物在不同条件制备产物层间距变化的原因.     

水在C12-EOx-C12•2Br/正己醇/正庚烷W/O微乳中的状态

以FT-IR方法研究了水/C₁₂-EO_x-C₁₂•2Br/正己醇/正庚烷形成的W/O微乳中水的状态. 结果表明, 其中的水存在4种状态, 分别为阳离子头基结合水、反离子结合水、类似本体的水以及束缚在微乳栅栏层中的水. 由解卷积技术分解FT-IR谱图, 进而获得每个表面活性剂分子对应于这4种状态水分子的数目n_N＋, n_Br-, n_b和n_f. 随着水含量(W₀)增加, n_b急剧增大, n_N＋少许上升, 而n_f和n_Br-维持不变, 这说明微乳水核逐渐长大, 且在所考察W₀范围内, 表面活性剂头基解离度保持不变.     

对BiVO4/BiPO4复合物可见光催化活性提高的研究

采用水热法合成出具有不同V、P物质的量之比的BiVO₄/BiPO₄复合物.n_V/n_P分别为:0.1/9.9、0.5/9.5、1/9、3/7、5/5.采用 XRD、FE-SEM、EDS、拉曼、可见光光度计、漫反射以及电化学等测试手段对BiVO₄/BiPO₄复合物进行表征.在可见光条件下降解亚甲基蓝来评价BiVO₄/BiPO₄复合物的光催化活性.结果显示,当n_V/n_P<3/7的时候,BiVO₄/BiPO₄复合物的光催化活性随着BiVO₄含量的增加而增加,当n_V/n_P=3/7的时候,复合物具有最佳的光催化性能,反应速率常数k为0.005 1 min^-1,是纯BiPO₄的23.2倍.BiVO₄/BiPO₄复合物的光催化机制主要是由于BiVO₄的加入,提高了电子-空穴的分离率,进而提高了光催化活性.     

BiVO4/BiPO4复合物的制备及可见光催化性能

采用水热法合成出具有不同V、P物质的量之比的BiVO₄/BiPO₄复合物.n_V/n_P分别为:0.1/9.9、0.5/9.5、1/9、3/7、5/5.采用 XRD、FE-SEM、EDS、拉曼、可见光光度计、漫反射以及电化学等测试手段对BiVO₄/BiPO₄复合物进行表征.在可见光条件下降解亚甲基蓝来评价BiVO₄/BiPO₄复合物的光催化活性.结果显示,当n_V/n_P<3/7的时候,BiVO₄/BiPO₄复合物的光催化活性随着BiVO₄含量的增加而增加,当n_V/n_P=3/7的时候,复合物具有最佳的光催化性能,反应速率常数k为0.005 1 min^-1,是纯BiPO₄的23.2倍.BiVO₄/BiPO₄复合物的光催化机制主要是由于BiVO₄的加入,提高了电子-空穴的分离率,进而提高了光催化活性.     

Rheological behavior of PAA–C n TAB complex: influence of PAA charge density and surfactant tail length in PAA semidilute aqueous solution

Interactions between anionic polyelectrolyte, poly(acrylic acid) (PAA), and cationic surfactant, alkyltrimethylammonium bromide (C _n TAB), were investigated by rheological measurements in semidilute PAA solution. The dependences of the rheological behavior on the chain length of the surfactant, PAA neutralization degree, and temperature were discussed. The results revealed that both dodecyl and cetyltrimethylammonium bromides (C₁₂TAB and C₁₆TAB) could increase the viscosity of PAA solution when the surfactant amounts surpassed a critical surfactant concentration (C _c), and C _c of C₁₆TAB was lower than that of C₁₂TAB at same PAA neutralization degree. The increase of viscosity is attributed to the surfactant micelles bridging of the polymer chains and confine the mobility PAA chain. On the other hand, it is found that the hydrogen bonding also played an important role in the PAA–C _n TAB system, especially in lower neutralization degree PAA solution, which results in the viscosity increase rapidly with the added surfactant into lower neutralization degree PAA solution.     

Intercalation of diamines into zirconium phosphate-phosphite: A layered compound with asymmetric layers

Many primary diamines H₂N(CH₂)_nNH₂ (all the members withn ranging from 0 to 12 with the exception ofn =I 1) have been intercalated within the phosphate regions of layered zirconium phosphate-phosphite. As a general rule, intercalation occurs in two steps that are not well differentiated. The first one leads to intercalation compounds in which the diamines are arranged with their alkyl chain oriented parallel to the layers; the second one to the fully intercalated compounds. These latter compounds have composition Zr(HPO₄)_0.7(HPO₃)1,3-yNH₂(CHn2)·NH₂, withy ranging from 0.36 to 0.49 depending on the nature of the diamine. Not all the diamine molecules are thus diprotonated and they show a tendency to reach a y value of 0.5, corresponding to the total occupancy of the crystal sites available for intercalation. Diamines are arranged as a monolayer of extended molecules and an evident even-odd alternation of the interplanar spacing has been observed.A comparison with the intercalation of-zirconium phosphate for the same diamines is also made.     

Mass transfer kinetics of graphene oxide prepared by chemical oxidation intercalationg assisted ultrasonic field

The key step of the control reaction for the preparation of graphene oxide (GO) by chemical oxidation of KMnO₄/ concentrated H₂SO₄ oxidation system is the intercalation mass transfer process of oxidizer in graphite. Ultrasonic field can promote the intercalation mass transfer process, but the mass transfer kinetics remains unclear. In this paper, the kinetic model of mass transfer coefficient of graphene oxide sheet intercalated by Mn₂O₇ oxidizer in ultrasonic field was established. The Mn₂O₇ intercalation process after the intervention of the ultrasonic was simulated by COMSOL Multiphysics 5.5 simulation software. The results show that the ultrasonic field makes the Mn₂O₇ solution inside and outside the graphite layer turbulent, and the ultrasonic intervening time has little influence on the concentration distribution and diffusion rate of the solution outside the graphite layer, while it has great influence on the concentration distribution and little influence on the diffusion rate change inside the graphite layer. These results contribute to the improvement of the mass transfer theory for the preparation of GO by ultrasonic assisted chemical oxidation.     

Effect of cationic surfactant cetyltrimethylammonium bromide on the enzymatic hydrolysis of cellulose

Effect of cationic surfactants alkyltrimethylammonium bromide (C_nTAB) with varied alkyl chain lengths on the enzymatic hydrolysis of Avicel and the surface charge of cellulase was investigated. Enzymatic hydrolysis of Avicel increased linearly from 42.1 to 61.4 % with the increase of the concentration of cetyltrimethylammonium bromide (C₁₆TAB) logarithmically from 0.0001 to 0.01 mM, and reached a maximum value at the concentration of 0.01–0.03 mM. When the concentration was increased further, the cellulase solution became positively charged and the enzymatic hydrolysis of Avicel decreased rapidly. With the increasing alkyl chain length, C_nTAB provided more proton and neutralized the negative charge of cellulase more obviously. Therefore, the required concentration of C_nTAB could be less to enhance the enzymatic hydrolysis of Avicel. In addition, C₁₆TAB could enhance enzymatic hydrolysis efficiency of corncob at high solid content from 35.0 to 56.3 %; C₁₆TAB could reduce about 60 % of the cellulase loading in the enzymatic hydrolysis of corncob to obtain the same glucose yield. Effect of C₁₆TAB on the enzymatic hydrolysis of typical pretreated softwood and hardwood was also investigated. This study laid the foundation for using C_nTAB to recover cellulase, and provided the design direction for cellulase with higher activity and better stability by adjusting its hydrophilicity and chargeability.     

Study of host–guest interaction between ß-cyclodextrin and alkyltrimethylammonium bromides in water

Cyclodextrins were found to play important roles in self-assembly systems of surfactants. The interactions between host molecule ß-cyclodextrin (CD) and model cationic surfactants, alkyltrimethylammonium bromides with different alkyl chain length: dodecyl-(C₁₂TAB), tetradecyl-(C₁₄TAB) and hexadecyl-(C₁₆TAB) are studied by means of conductivity measurements at 313.2 K. The data obtained indicate that inclusion complexes (CD:S⁺) had formed, and apparent critical micelle concentration (CMC*) is equivalent to the combined concentrations of surfactant monomers complexed with the CD and that of a free dissolved monomer in equilibrium with the micellized surfactant without CD. Inclusion complexes were characterized by an equilibrium binding constant K ₁₁, which value increases as the length of alkyl chains, and consequently the hydrophobicity, increases. From mathematical model the concentrations of the uncomplexed cyclodextrin, uncomplexed surfactant ion, and inclusion complex in the submicellar, as well as in the micellar range were calculated. The competition between the micellization and complexation processes leads to the existence of a significant concentration of free CD in equilibrium with the micellar aggregates. The percentage of uncomplexed cyclodextrin in equilibrium with the micelles is independent on cyclodextrin concentration for a particular ternary system and is 31, 37, and 34 % for C₁₂TAB/water/ß-CD, C₁₄TAB/water/ß-CD and C₁₆TAB/water/ß-CD, respectively. By using standard Gibbs free energy for micellization and surfactant complexation by CD, we can explain the observed behavior.     

Intercalation Study of Low‐Molecular‐Weight Hyperbranched Polyethyleneimine into Graphite Oxide

We report for the first time the intercalation of low‐molecular‐weight hyperbranched polyethyleneimine (PEI) into graphite oxide (GO) for the facile, bulk synthesis of novel graphene‐based hybrid (GO‐PEI) materials exhibiting tailored interlayer galleries. The size of the intercalant as well as the loading in GO were systematically investigated to determine their contribution to the basal spacing of the resulting materials. Powder X‐ray diffraction measurements demonstrated the generation of constrained hybrid systems along the c axis that exhibit considerably increased interlayer distances compared with the starting, pristine GO. The results of X‐ray photoelectron and FTIR studies are consistent with a “grafting‐to” process of the intercalated PEI with the oxygen functional groups present along the GO framework. Furthermore, it was found that a great number of the nitrogen‐containing groups in PEI still remain available within the newly formed, confined micro‐environment of intercalated GO galleries. The increased surface area of the GO‐PEI hybrids in conjunction with the remaining available active groups of intercalated PEI render the synthesised hybrids very attractive candidates as nanostructured adsorbents.     

药物-无机复合材料姜黄素嵌入镁铝水滑石的合成、表征及缓释性能的研究

采用共沉淀和离子交换方法将药物姜黄素(Cur)嵌入到Mg-Al-LDHs层间,制备了一种新型的药物-无机复合材料,借助XRD,FTIR和TG-DTA等手段对样品进行了表征。结果表明,Cur阴离子以平行或者单层、沿其短轴方向垂直嵌入到层间;与主体层板通过氢键与静电作用形成超分子结构;该超分子结构姜黄素-水滑石复合材料与姜黄素相比,其热稳定性、耐酸性及缓释性能均有大幅度提高,缓释实验数据符合Bhaskar方程和一级动力学方程模型。