Jeffamine聚醚胺改性合成介孔及超微孔氧化硅微球

通过对Jeffamine ED2003进行硬脂酸接枝,获得了一种在水溶液中能够进行自组装的新型聚醚酰胺高分子表面活性剂,命名为ED2003-fa-18.以ED2003-fa-18聚醚酰胺高分子表面活性剂为模板,以正硅酸乙酯(TEOS)为无机硅源,在酸性条件下水热合成了介孔及超微孔氧化硅微球.利用粉末X射线衍射(XRD)、N₂物理吸附、红外光谱(IR)、核磁共振波谱(¹H NMR)、扫描电镜(SEM)和透射电镜(TEM)等方法对合成样品进行了表征.研究结果表明,通过改变合成体系中表面活性剂的浓度,可控合成出了有序的介孔及超微孔氧化硅材料.当ED2003-fa-18的浓度为1wt%时,合成的材料为介孔氧化硅,样品的最可几孔径约为2.2 nm.当ED2003-fa-18的浓度从3wt%增加到7wt%时,样品的最可几孔径从1.98 nm减小到1.94 nm,得到的样品为超微孔氧化硅材料.样品的比表面积在500 m²·g^-1左右,孔体积在0.3 cm³·g^-1左右.由SEM照片可知,所合成的介孔及超微孔氧化硅材料均为由20~30 nm的球形纳米颗粒进一步团聚形成的2~4 μm的紧密堆积的实心微球.     

对苯二甲酸-锌配合物孔结构的研究

以硝酸锌和对苯二甲酸为反应物,N,N′-二甲基甲酰胺(DMF)为溶剂,用溶剂热法合成出结构稳定的对苯二甲酸-锌配位化合物(MOF-L)。并采用XRD、TG、低温N₂吸附等测试手段对合成的MOF-L进行了表征。结果表明,样品的孔径分布均呈双峰型,孔结构主要由孔径小于1 nm的微孔和少量1.5～2.0 nm的超微孔组成,且小于0.7 nm的极微孔丰富;其表面在极微孔和超微孔范围存在两种吸附位。300 ℃煅烧的样品,Langmuir比表面积和单点总孔容分别为1 243 m²·g^-1和0.46 cm³·g^-1,在77 K、1.0 bar时的储氢容量为1.3wt%。400 ℃煅烧后,骨架扭曲坍塌,Langmuir比表面积、总孔容及储氢容量分别下降为1 113 m²·g^-1、0.43 cm³·g^-1和0.8wt%。     

功能化有序介孔碳对重金属离子Cu(II)、Cr(VI)的选择性吸附行为

以三嵌段共聚物F127为模板剂, 酚醛树脂为碳源, 正硅酸乙酯为硅源, 三组分共组装合成介孔碳?氧化 硅纳米复合物, 再经HF去除氧化硅, 得到有序介孔碳(OMC). X射线衍射(XRD)、透射电子显微镜(TEM)、低温 N2吸脱附(BET)等测试表明, 所得样品具有高度有序的介孔结构, 比表面积和孔容分别为1330 m²·g^-1和2.13 cm³·g^-1, 平均孔径6.4 nm. 对其先氧化、后氯化、再胺化, 得到不同胺基接枝量的胺化介孔碳(C-NH₂(m), m为加入的乙二胺的质量(g)). 傅里叶变换红外(FT-IR)光谱表征结果证实, 胺基官能团成功接枝到有序介孔碳表面.TEM测试表明介孔碳的有序孔道结构得到了较好的保持. 以有序介孔碳、胺化介孔碳作吸附剂对Cu(II)、Cr(VI)进行选择性吸附研究. 结果表明: 功能化修饰前, 样品对Cu(II)、Cr(VI)饱和吸附量分别为213.33、241.55 mg·g^-1; 修饰后饱和吸附量可分别达到495.05、68.21 mg·g^-1. 功能化介孔碳表现了较强的选择性吸附Cu(II)的能力.     

高度有序介孔氧化硅材料SBA-15：高浓度氨基官能化及氨基及氨基团的可利用性

采用简单的方法合成高浓度氨基修饰的高度有序氧化硅材料并深入研究氨基官能化材料的孔结构以及氨基的存在状态和可利用性。结果表明,氨基基团共价连接到SBA-15的孔表面,即使初始合成体系中的APTES（氨丙基三乙氧基硅烷）浓度高达30mol%时材料依然保持高度的有序性。合成体系中APTES浓度为20％的样品还保持良好的介孔结构,比表面积为680 m²·g^-1,孔容为0.89 cm³·g^-1,此介孔结构中的氨基官能团对镍离子表现出很强的亲和力,Ni²⁺的吸附量高达1.88 mmol·g^-1,相比之下未官能化的SBA-15对Ni²⁺没有吸附作用。当初始合成体系中APTES的浓度进一步增大到30％时,修饰到介孔氧化硅材料的氨基含量也随之增大,但由于材料的孔隙度急剧降低,这些氨基的可利用性也降低。     

锂硫电池正极用硫/介孔碳复合材料的制备及电化学性能

制备了以十二烷基硫酸钠(SDS)为模板的介孔碳,并将介孔碳和单质硫采用熔融渗透法复合制得硫/介孔碳复合材料。SEM、TEM和BET结果显示介孔碳成直径约为500 nm的大小均一的球体,存在孔径为2 nm的微孔;单质硫充分填充在介孔碳的微孔中。以硫/介孔碳复合物作为锂硫电池正极材料时显示出高的电化学性能。初始放电容量高达1519 mAh·g^-1,在200 mA·g^-1的电流密度下充放电200个循环后依然能保持在835 mAh·g^-1。硫/介孔碳复合材料的高倍率性能和优异的循环稳定性,源于介孔碳良好的导电性及其孔结构的固硫作用。     

表面氨基高密度化介孔氧化硅的合成及其高效去除酸性橙7

以月桂酸为阴离子表面活性剂,3-胺丙基三乙氧基硅烷(APTES)为共结构导向剂,合成了高含量氨基功能化介孔氧化硅材料(AFMS)。以AFMS为吸附剂对溶液中酸性橙7(AO7)进行吸附,对影响AO7吸附效率的相关因素进行了详细研究,结果表明,溶液pH值及温度影响较大。吸附动力学表明,本研究中合成的AFMS对AO7的吸附速率极快。Sips吸附模型对吸附等温线模拟效果最好,从中可知AO7在样品D(由3.0 mL正硅酸乙酯及1.4 mL APTES合成)上的最大吸附量为1.26 mmol·g^-1,远远高于相关文献报道的值。此外,通过吸-脱附循环实验证明,样品D具有良好的稳定性。     

立方介孔相含钕氧化硅的合成与表征

以十六烷基三甲基溴化铵为结构导向剂，通过水热法合成了具有立方结构的含钕Nd-MCM-48介孔分子筛材料。XRD和TEM测试表明当n_Nd/n_Si<0.05时可以获得典型的长程有序介孔立方结构相，随n_Nd/n_Si比的增加，晶胞参数的增大和红外吸收光谱(FT-IR)的变化为Nd进入介孔分子筛骨架中提供了有力证据。N₂吸附-脱附实验给出了其BET表面积为1 195 m²·g^-1，BJH平均孔径为3.6 nm。紫外-可见漫反射光谱(UV-Vis)证明钕氧形成一种八面体结构。X射线光电子能谱(XPS)进一步证明钕主要以三价形式存在于立方介孔分子筛骨架中。     

疏水介孔二氧化硅膜的制备与表征

用甲基三乙氧基硅烷(MTES)代替部分正硅酸乙酯(TEOS)作为前驱体，以聚乙烯醚-聚丙烯醚-聚乙烯醚三嵌段共聚物(P123)作有机模板剂，通过共水解缩聚反应制备了甲基修饰的介孔SiO₂膜。利用N₂吸附、FTIR、²⁹Si MAS NMR以及接触角测量仪对膜的孔结构和疏水性进行了表征。结果表明，修饰后的膜材料具有良好的介孔结构，最可几孔径为4.65 nm，孔体积为0.69 cm³·g^-1，比表面积为938.4 m²·g^-1；同时疏水性明显提高，当n_MTES/n_TEOS达到1.0时，其对水的接触角达到109°± 1.1°。气体渗透实验表明气体通过膜孔的扩散由努森机制所控制。     

汉麻杆基活性炭表面织构与储氢性能的研究

以天然汉麻杆为原料,采用KOH化学活化的方法改变活化时间制备出了高比表面积活性炭,并且对其表面进行硝酸氧化处理,研究活性炭表面化学状态对其吸附性能的影响。采用77 K低温氮气吸附和FTIR对样品进行了表征,并在77 K、100 kPa的条件下测定样品的氢气吸附等温线。结果表明,所有样品具有较高的比表面积(2 435.93～3 240.95 m²·g^-1)和总孔容(1.3～1.98 cm³·g^-1),且随活化时间的延长而增加,3.5 h达到最大值,之后由于骨架坍塌有所减小。所有样品的孔径分布较为一致呈多峰型分布,主要以小于2 nm的微孔为主,同时含有少量的中孔和大孔。活化3.5 h样品的吸氢量最大,达到3.28wt%。研究发现,吸氢量受比表面积和孔容等参数影响较大,77 K下不仅小于2 nm的微孔对活性炭吸氢行为贡献较大,中孔也有十分重要的影响。样品经硝酸氧化处理后,BET比表面积和总孔容均在一定程度上减小,而氢气吸附量也有所降低。     

高比表面CexZr1-xO2复合氧化物的制备及表征

分别采用共沉淀法和阴离子表面活性剂模板法制备了Ce_xZr_1-xO₂复合氧化物。采用XRD、AFM、FTIR以及N₂吸附-脱附等方法对样品进行了表征。结果表明，共沉淀法合成的样品在500 ℃煅烧2 h后，生成了立方相Ce_0.75Zr_0.25O₂和四方相Ce_0.5Zr_0.5O₂固溶体，比表面积为62.1 m²·g^-1，孔体积为0.097 cm³·g^-1；以阴离子表面活性剂十二烷基苯磺酸钠(SDBS)为模板剂，乙二胺为助模板剂合成的样品在500 ℃煅烧2 h后，生成了纯四方相Ce_0.5Zr_0.5O₂固溶体，比表面积为180 m²·g^-1，孔体积为0.182 cm³·g^-1。结果表明，以阴离子表面活性剂SDBS为模板剂，可以合成高比表面积且具有介孔结构的Ce_0.5Zr_0.5O₂复合氧化物；加入乙二胺作为助模板剂可明显的提高比表面积和孔体积。     

Sol-Gel Particulate Float Process to Make Vitreous Silica Bodies

Particulate sol-gel technology uses larger particles than that of alkoxide-derived gels and provides larger pore sizes in the gelled object. This allows relatively rapid drying and fabrication of large rods or tubular shapes. However, the formation of more complex or flat shapes, which require extensive surface contact with a mold, is more difficult. The shrinkage during drying, with the significantly greater stress of surface friction due to adhesion, frequently leads to cracking.We have demonstrated a solution to this problem by floating the gel on the surface of a dense liquid. Dry silica panels up to 28 × 40 × 0.7 cm³ were prepared in this way. The use of patterning molds allowed the fabrication of more sophisticated shapes. These bodies were sintered to transparent vitreous silica articles of near net dimensions.     

Pentacyanoferrates(II) on the surface of organomodified silica gel: The matrix effect

Pentacyanoferrate(II) absorbed on a silica gel surface previously modified with 3-aminopropyl and 3-imidazolylpropyl groups were characterized by¹³C MAS/NMR, FT-IR, Mössbauer spectroscopy, and cyclic voltammetry. FT-IR and¹³C MAS/NMR data indicated that the pentacyanoferrate(II) complex is bonded to the surface by the nitrogen atom of the functional group. The differences in the isomeric shifts, the quandrupole splittings and the midpoint potentials of the adsorbed complexes in comparison with the model complexes were attributed to the matrix polar effect—i.e., the interaction of the complex with polar groups on the silica surface.     

不同酸对介孔二氧化硅球表面形貌和介相结构的影响

在室温、不同酸性条件下合成出微米级球形介孔二氧化硅材料，通过XRD、SEM以及氮气吸附等手段对介孔二氧化硅材料进行了表征。用TEM跟踪不同反应时间介孔二氧化硅球的形成，对这些球颗粒的合成机理进行了讨论，同时探讨了不同酸性条件下介孔二氧化硅表面形貌和介相结构的变化。     

Alginate Microspheres Loaded with Animal Cells and Coated by a Siliceous Layer

Animal cells or cell aggregates are suspended in Na-alginate solution and extruded under a flow of air saturated with silicon alcoxides. The immediate formation of a sol-gel siliceous membrane on the microdrop surface allows the reaction with Ca²⁺⁺, leading to solid Ca-alginate, and yields homogeneous, stable microcapsules 200 m in diameter. The cell function of the encapsulated biomass were tested in specific protein production, which is not affected by the siliceous membrane protection of Ca-alginate microcapsules. This fact, and the observed increase in mechanical stability and chemical durability, indicate that valuable features of silica encapsulation are added to those proper to Ca-alginate.     

Testing the polarity and adsorptivity of nondeactivated GC capillary surfaces

Split injection of 1-pentanol headspace on to raw or treated fused silica tubing yields information on the characteristics of its surface (silanol concentration, polarity, adsorptivity). Fused silica tubing from three sources was compared. The effect of various leaching and etching procedures used for column preparation was studied, as was the stability of uncoated fused silica precolumns towards water and some organic solvents.     

Synthesis and Catalytic Applications of Sulfonic Acid Group–Functionalized Nano- and Microsilica Structures

Sulfonic acid group–functionalized nano- and microsilica with different sizes and shapes were synthesized. Silica nanospheres with an average size of 225 nm, silica microtubes, and fine silica gel were prepared and functionalized by sulfonic acid. Their catalytic activity was investigated in the three-component Biginelli reaction for the synthesis of dihydropyrimidinones.     

Preparation of octadecyl modified column gels using heat-treated silicas and their retention behaviour in high-performance liquid chromatography

Summary The effect of silanol groups on three types of octadecylmodified column gels using heat-treated silicas by calcination has been studied by high-performance liquid chromatography. After heat-treating at 180°C, 500°C and 950°C, the silicas treated with octadecyldimethylchlorosilane were used for the measurement of physical and chemical analysis. From elemental carbon analysis data, the reactive silanol group concentrations, _OH(s), were determined to be 2.0 in the 180°C treated silica, 2.1 in the 500°C treated silica and 1.6 in the 950°C treated silica, respectively (original silica: mean pore diameter 116 Å, specific surface area 298 m²/g, pore volume 1.22 ml/g, particle size 5.0 m). The separation factors, , of pyridine versus phenol were measured to be 0.79 on 180°C treated silica, 0.91 on 500°C treated silica and 1.98 on 950°C treated silica, using acetonitrile-water mixtures as the eluent. And then, on the basis of the physico-chemical and chromatographic data, the three types of octadecyl modified column gels using heat-treated silicas by calcination have been compared.     

硅氧聚合度对细胞毒性的影响

本文采用家兔肺泡巨噬细胞(AM)存活率和细胞过氧化脂质(LPO)值为测定指标,研究了硅氧的聚合度对其细胞毒性的影响。结果表明:各种聚合度的硅氧都有一定的细胞毒性,聚合度愈大,细胞毒性也愈大。胶体SiO_2的粒径增大,其细胞毒性降低。十硅酸盐及粒径小于5nm的硅溶胶的细胞毒性大于α-石英。聚合度小于6的低聚硅酸及其盐、粒径18nm以上的硅溶胶以及硅胶H的毒性皆小于α-石英。本实验细胞存活率降低和过氧化脂质值升高的趋势基本一致,这表明硅氧可能主要与细胞表面膜作用,膜上磷脂等表面活性物质被氧化和变性,从而导致细胞损伤。     

电解质诱导聚集初级粒子制备介孔SiO_2材料

在无模板剂的条件下,通过在Stber合成过程中引入外加电解质成功地制备了具有介孔结构的SiO2粒子.实验结果表明,通过电解质的加入可以诱导Stber过程中初级SiO2粒子的聚集,从而得到了具有介孔结构和较强表面吸附能力的SiO2粒子.     

Thermal and Temporal Aging of Two Step Acid-Base Catalyzed Silica Gels in Water/Ethanol Solutions

Dissolution and reprecipitation of silica during aging in water improve the wet gels mechanical stiffness and strength, and hence shrinkage during supercritical drying is reduced. We have investigated how the strength and stiffness of a 2-step TEOS acid-base catalyzed wet gel can be improved by aging in a solution of water/ethanol (20–40 vol%) at various temperatures (20–70°C) and time (2 h and 24 h) and how this influences the aerogels properties. The linear shrinkage during supercritical drying was reduced from 29% to 2% by introducing the aging step in the 20 vol% water/ethanol solution for 24 h at 60°C.We have also in previous works introduced the idea of preparing ambient pressure dried silica aerogels by increasing the wet gels stiffness by aging in a TEOS solution until shrinkage during drying is almost eliminated. The gels aged in the water/ethanol solutions were further aged in a TEOS/ethanol solution and the effect of the increasing water content in the pore liquid was studied. A xerogel density of 0.20 g/cm³ is reported for gels with a shear modulus (G) of 30 MPa.