SiO_2/ZrO_2复合溶胶稳定性的研究

以正硅酸乙酯(TEOS)、无水乙醇(EtOH)、水和氧氯化锆(ZrOCl2·8H2O)为原料,盐酸(HCl)为催化剂,四乙基溴化铵(TEAB)为添加剂,采用溶胶-凝胶工艺制备SiO2/ZrO2复合溶胶。正交试验和单因素综合分析了乙醇、氧氯化锆、TEAB、pH、水解反应温度对复合溶胶凝胶时间的影响。总结出了稳定性良好的SiO2/ZrO2复合溶胶的制备工艺及以上各因素对复合溶胶稳定性的影响趋势。结果表明:在室温、pH为0.7条件下,实验最优配比是:TEOS∶EtOH∶H2O∶ZrOCl2·8H2O∶TEAB=0.7∶40∶6∶0.3∶0.07;复合溶胶的凝胶时间随着乙醇、TEAB的增加而延长,随着氧氯化锆、水解反应温度的增加而缩短,随着pH的增加先延长后缩短。     

SiO_2/ZrO_2复合溶胶稳定性影响因素的研究

以氧氯化锆(ZrOCl_2·8H_2O)和正硅酸乙酯(TEOS)为前驱体,四乙基溴化铵(TEAB)和N,N-二甲基甲酰胺(DMF)为模板剂,采用溶胶-凝胶法制备SiO_2/ZrO_2复合溶胶。通过正交试验和单因素试验考察陈化温度、模板剂、锆含量和乙醇对SiO_2/ZrO_2复合溶胶稳定性的影响。结果表明:陈化温度对溶胶稳定性影响较大,溶胶稳定性随着陈化温度的升高显著下降;其次是锆含量,溶胶稳定性随锆含量的增加先降低后缓慢上升,最低点处n(ZrOCl_2·8H_2O)∶n(ZrOCl_2·8H_2O+TEOS)=0.15。     

溶胶-凝胶法制备SiO2溶胶正交试验的灰色关联分析

采用灰色关联矩阵分析理论,阐述了制备SiO2溶胶正交试验的灰色关联分析方法,给出了其算法并编制了相关的程序.对溶胶主要制备因素HNO\-3∶TEOS\,H\-2O∶TEOS和E\-tOH∶T EOS(摩尔比)对溶胶胶凝时间的影响程度进行了研究,对实际的科研工作具有指导意义.     

碱催化多孔二氧化硅薄膜的制备和性能表征

以水为介质,NH3·H2O为催化剂,丙三醇(C3H5(OH)3和聚乙烯醇(PVA)为添加剂,正硅酸乙脂(TEOS)溶胶 凝胶工艺可制备纳米多孔二氧化硅薄膜。体系的H2O/TEOS>15,TEOS的水解 聚合过程可通过添加剂效应,pH效应等控制。碱催化会使二氧化硅的溶解度增大,也能使二氧化硅胶粒带负电荷,抑制了二氧化硅胶粒之间的聚合长大,而丙三醇与TEOS的水解中间Si(OR)4-x(OH)x结合,抑制其与二氧化硅胶粒的聚合。聚乙烯醇(PVA)能使二氧化硅溶胶具有网状结构,使二氧化硅溶胶易于成膜。该工艺制备的多孔二氧化硅薄膜具有纳米多孔结构。其Vicker硬度在600～800N/mm2,热导率<0.2W·m-1K-1。     

pH值及含水量对自蔓燃制备TiO_2光催化性能的影响

为了考察pH值及含水量对溶胶-凝胶自蔓燃法制备TiO2粉体光催化性能的影响,以TiO(NO3)2为前驱体,在原料、燃烧剂和燃烧助剂的物质的量比为n(TiCl4)∶n(C6H8O7)∶n(NH4NO3)=1∶1∶3,以及煅烧温度550℃不变的情况下,改变溶胶pH值和含水量,制备TiO2粉体,利用X射线衍射和扫描电镜进行结构表征,通过降解亚甲基蓝验证光催化性能。结果表明:该条件下制备的TiO2粉体具有松散、多孔的特性,晶型为锐钛矿。在pH值为7、含水质量分数为50%的条件下,TiO2的光催化活性最高。     

纳米TiO2/SiO2复合催化剂的制备与表征

以钛酸四丁酯、正硅酸乙酯作为前驱体,冰醋酸作为水解抑制剂,用溶胶-凝胶法制备了纳米TiO2/SiO2复合物.讨论了加水量、稳定剂、催化剂、乙醇用量、反应温度等工艺因素对制备过程的影响.用X射线衍射、红外光谱、比表面积仪等测试手段对纳米TiO2/SiO2复合粒子进行了表征.结果表明,用溶胶-凝胶法制备TiO2/SO2复合光催化粒子,整个反应采用滴加方式;各反应组分用量为n(TEOS+TBOT) :n(EtOH) :n(HCl) :n(H2O)=1 :16 :0.06 :4,n(TBOT) :n(HAc)=1 :0.6;反应温度为室温.制备得到的纳米TiO2/SiO2复合粒子主要以锐钛矿型存在;SiO进入TiO2晶体结构中,两者以化学键相结合;TiO2/SiO2复合粒子的比表面积要比纯TiO2粒子的比表面积大得多,当xTi :xsi=3时,TiO2/SiO2复合粒子比表面积达389.11 m2/g.     

TiO2-SiO2纳米多孔材料常压干燥制备

以廉价的TiCl4和工业水玻璃为原料,通过溶胶-凝胶法制得了TiO2-SiO2复合湿凝胶,用三甲基氯硅(TMCS)/乙醇(EtOH)/己烷(Hexane)溶液对湿凝胶进行改性,再经常压干燥制备了TiO2-SiO2纳米多孔材料.利用扫描电子显微镜(SEM)、红外吸收光谱(FTIR)和N2吸附/解吸法对纳米多孔材料的形貌和性质进行了分析.结果表明,所制备的TiO2-SiO2纳米多孔材料为轻质块状固体,具有连续多孔结构,密度为0.14～O.25g/cm3,孔隙率为88.6%～93.6%,比表面积为716.8～802.7m2/g.吸附和光催化降解罗丹明B的结果表明,n(Ti):n(Si)=1:3的样品吸附率最高,20h时达到86%,n(Ti):n(Si)=1:2的样品光催化降解率最高,10h时可达到94%.     

γ-氯丙基三乙氧基硅烷对SiO_2-AgCl复合溶胶凝胶薄膜性能的影响

以正硅酸乙酯(TEOS)为前驱体经γ-氯丙基三乙氧基硅烷(CPTES)改性后制备硅溶胶,与以醇盐硝酸银(AgNO3)为前驱体制备的AgCl溶胶共混后形成复合溶胶,采用浸渍提拉法涂覆于PET基片表面形成SiO2-AgCl复合薄膜,采用SEM、FTIR、机械折叠、接触角测试、烘干质量法、贴膜法研究硅烷偶联剂含量对溶胶-凝胶成膜过程、成膜特性等的影响。结果表明,当摩尔比n(CPTES)∶n(TEOS)=1时可获得表面光滑膜厚均匀,具有良好膜基结合力、疏水性能、耐水性能及抗菌性能的SiO2-AgCl复合薄膜。     

溶胶-凝胶法超疏水含氟硅聚氨酯丙烯酸酯/SiO2杂化涂层的制备

以正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES)为前驱体,在含氟硅聚氨酯丙烯酸酯(FSiPUA)复合乳液中采用溶胶-凝胶法制备了超疏水杂化涂层。考察了MTES/TEOS的摩尔比和FSiPUA复合乳液用量等对涂层表面粗糙度、疏水性、成膜性等表面性能的影响。通过扫描电镜和接触角仪表征了涂层的微观结构及疏水性,利用马尔文粒度分析仪和傅里叶红外光谱仪分析了二氧化硅(SiO2)的平均粒径和化学结构。结果表明,随着MTES/TEOS摩尔比增加,杂化涂层的表面粗糙度逐渐下降,疏水性先增大后减小;随着FSiPUA复合乳液用量增加,涂层的成膜性逐渐变好;当(TEOS+MTES)∶C2H5OH∶NH3·H2O∶AMP-95的摩尔比为1∶6.67∶1.83∶0.24,MTES/TEOS摩尔比值为5,FSiPUA复合乳液用量为20%时,涂层具有超疏水特性,其水接触角(WCA)和滚动角(SA)分别为161.5°和2.8°,涂层表面对水滴具有优异的不粘附性。     

SiO_2气凝胶的常压干燥制备与性能表征

本实验以正硅酸乙酯(TEOS)为硅源,甲基三乙氧基硅烷(MTES)为共前驱体,超纯水(H_2O)为反应剂,无水乙醇(EtOH)为溶剂,盐酸(HCl)和氨水(NH_3·H_2O)为催化剂,采用酸碱两步催化二次改性常压干燥制备了超疏水性SiO_2气凝胶。利用N_2吸附-脱附测试、傅里叶变换红外光谱(FTIR)、X射线衍射(XRD)、扫描电镜(SEM)和接触角测定等手段对气凝胶的结构和性能进行表征,系统研究了水的用量、无水乙醇的用量以及溶胶的pH值对气凝胶性能的影响。结果表明:当TEOS、MTES、EtOH、H_2O物质的量比为1∶0.3∶14∶6时制备的气凝胶性能最好,其热导率为0.021 2 W/(m·K),比表面积为920 m~2/g,孔径主要分布在2～20 nm,密度为0.109 g/cm~3,孔隙率为95.05%,接触角为158.7°。     

单因素对单分散二氧化硅微球制备的影响

以氨水为催化剂、正硅酸乙酯为硅源、醇为溶剂,采用改进的溶胶-凝胶工艺制备单分散SiO2微球,通过扫描电镜、激光粒度分析仪着重研究了正硅酸乙酯添加方式、反应温度、溶剂类型等单因素对SiO2的颗粒大小和形貌的影响.结果表明,正硅酸水解对醇溶剂是有选择性的,乙醇作为溶剂合成SiO2的单分散性和球形度最好.连续滴定和分步滴定更有利于单分散SiO2微球的形成.水解温度升高,生成的颗粒粒径将运渐增大,最佳反应温度为常温25℃或恒温水浴25～35℃.     

P(AM PS+AM)/SiO_2高吸水性杂化材料的制备及性能

研究了以2-丙烯酰胺基-2-甲基丙磺酸(AM PS)和丙烯酰胺(AM)共聚物为有机相,通过正硅酸乙酯(TEO S)引入S iO2无机相,采用溶胶-凝胶法制得了P(AM PS+AM)/S iO2高吸水性杂化材料,并着重研究了不同用量的TEO S对材料结构和性能的影响。采用傅立叶红外(FT-IR)、扫描电镜(SEM)等检测方法对材料进行了表征,同时对材料的透光性、吸液性能、热稳定性等进行了评价。结果表明,TEO S用量为5%(相对单体质量百分含量)左右制得的高吸水性杂化材料较为理想。     

Synthesis of shape-stabilized paraffin/silicon dioxide composites as phase change material for thermal energy storage

The shape-stabilized paraffin/silicon dioxide (SiO₂) composite phase change materials (PCM) were prepared by using sol–gel methods. Paraffin was used as the PCM, and silicon dioxide was acted as the supporting material. Fourier transformation infrared spectroscope (FT-IR) and scanning electronic microscope were used to determine the FT-IR spectra and microstructure of shape-stabilized paraffin/silicon dioxide composite PCM, respectively. The thermal properties and thermal stability were investigated by a differential scanning calorimeter and a thermogravimetric analysis, respectively. The SEM analysis showed that the paraffin was well dispersed into the porous network of silicon dioxide. DSC analysis indicated that the mass content of paraffin in silicon dioxide was up to 92.1%, and paraffin/silicon dioxide composites had solidifying temperature of 57.07 °C, solidifying latent heat of 59.66 kJ/kg, melting temperature of 58.10 °C, and melting latent heat of 139.59 kJ/kg.     

Comparative study of the porosity induced by CTAB and Tween as silica templates

In this study doped-silicon polymers were synthesized using the non-ionic surfactant Tween 80 as template. The obtained material was compared with silicates doped with the cationic surfactant CTAB. Both materials were synthesized by sol–gel process with tetraethoxysilane (TEOS) as silicon source. In the synthesis procedure reported herein the main difference to previous reports is that the obtained solids were dried smoothly at 55 °C avoiding surfactant calcination. The aim of this work is to obtain new biomaterials appropriate to be used for encapsulation devices in which the surfactant kept within the silica network has two roles: (1) to improve the mechanical resistance in drying–swelling processes preventing crack formation, (2) to hold and protect the encapsulated molecules keeping intact their bioactivity during TEOS polymerization. Structural features such as pore size and surface topology were studied by means of N₂ adsorption, X-ray diffraction and AFM microscopy. The influence of surfactant net charge and molecular shape on the materials obtained is discussed.     

SiO2/TiO2复合气凝胶的孔道结构研究

为了在常压干燥下制备高比表面积且具有多级孔道结构的SiO2/TiO2复合气凝胶,以正硅酸乙酯、钛酸丁酯为原料,利用低聚体聚合将分相平行引入到溶胶凝胶过程中,获得SiO2/TiO2醇凝胶,并通过溶剂替换技术实现气凝胶的常压干燥制备.不同硅钛比气凝胶的内部结构研究表明:合成的气凝胶是由纳米SiO2和TiO2颗粒分散复合而成的介孔块体,其中Ti—O—Ti、Si—O—Si和Ti—O—Si键相互交织.气凝胶的结构变化是分相与溶胶凝胶过程相互竞争的结果.Si含量能显著改善气凝胶的结构,当n(Ti)∶n(Si)为3∶1时,比表面积高达712.2 m2/g,平均孔径为3.36 nm;当n(Ti)∶n(Si)为1.5∶1时,复合气凝胶具有明显双连续孔道,比表面积高,同时孔状结构清晰.     

TEOS-PEG无机-有机杂化复合材料的研究

阐述了溶胶凝胶法合成ＴＥＯＳＰＥＧ（正硅酸乙酯聚乙二醇）无机有机杂化复合材料的基本原理,且成功地合成出该材料,同时进行了红外表征及热分析,探索了ＴＥＯＳＰＥＧ凝胶比表面积、折射率及结构的影响因素。ＴＥＯＳＰＥＧ无机有机杂化复合材料具有优良的物化性能及光学性能,可广泛用作各种特殊用途的光学元件。     

Effect of film thickness and annealing on optical properties of TiO2 thin films and electrical characterization of MOS capacitors

Titanium dioxide (TiO₂) thin films were deposited on glass and silicon (100) substrates by the sol–gel method. The influence of film thickness and annealing temperature on optical transmittance/reflectance of TiO₂ films was studied. TiO₂ films were used to fabricate metal–oxide–semiconductor capacitors. The capacitance–voltage (C–V), dissipation–voltage (D–V) and current–voltage (I–V) characteristics were studied at different annealing temperatures and the dielectric constant, current density and resistivity were estimated. The loss tangent (dissipation) increased with increase of annealing temperature.     

SiO_2-TiO_2-ZrO_2溶胶低温固化涂层的组织结构及耐盐雾腐蚀性能

SiO2-TiO2-ZrO2溶胶高温固化制备的涂层无光泽。以正硅酸乙酯(TEOS)、钛酸丁酯(TBT)和氧氯化锆(ZrOCl2.8H2O)等为原料制备SiO2-TiO2-ZrO2溶胶,研究了其不同温度固化后的粉末的分子结构、物相及热性能,并分析了溶胶低温(100℃)固化处理所得涂层的表面形貌、透过率及耐盐雾腐蚀性。结果表明:100～800℃固化,TEOS与TBT水解完全,经缩合反应形成Ti-O-Si键,Zr4+可能存在于Ti-O-Si的网络结构间隙中;低温(100℃)固化所得干凝胶为非晶态,热稳定性好;低温(100℃)固化制得的涂层无色透明、有光泽,可保持基底原色,表面均匀、无开裂,能对基材起到良好的防腐蚀作用。     

二氧化硅微球的制备与形成机理

在酯-醇-水-碱体系中以正硅酸乙酯为硅源、氨水为催化剂、乙醇为溶剂,采用改进的溶胶-凝胶法合成了二氧化硅球形颗粒。采用红外光谱、BET吸附曲线、扫描电镜等手段重点研究了正硅酸乙酯加料方式对二氧化硅粒径和形貌的影响。分析表明,采用正硅酸乙酯分步滴定法能提高二氧化硅微球的球形度、窄分布、单分散与致密性。同时,在反应温度25℃、正硅酸乙酯浓度0.12mol/L、氨浓度为15.0mol/L、去离子水浓度0.90mol/L、无水乙醇浓度2.35mol/L、pH值为9～12的条件下,获得了直径约200～250nm、粒径一致性约为0.5、分布偏差约为7.5%的球形二氧化硅单分散颗粒;研究和讨论了二氧化硅微球的形成机理。     

Facile synthesis and morphology control of zeolite MCM-22 via a two-step sol–gel route with tetraethyl orthosilicate as silica source

MCM-22 zeolite was synthesized via a two-step sol–gel route (low pH sol–gel reaction followed by high pH crystallization) under static hydrothermal conditions using tetraethyl orthosilicate (TEOS) as silica source. Various parameters that significantly influence the synthesis results during both the hydrolysis reaction of TEOS in acid media and the hydrothermal reaction in base media were investigated in detail. The produced samples were characterized by XRD, ICP, and SEM techniques. It is found that pure MCM-22 with high crystallinity can be obtained via the novel two-step sol–gel route in a broad window of reaction conditions. The increase of temperature and pH value for the hydrolysis of TEOS favors the shortening of crystallization time and decreasing of MCM-22 particle size. Moreover, by adjusting the hydrothermal reaction parameters, such as increasing the crystallization temperature, increasing the alkalinity of the synthesis gel mixture, and decreasing the SiO₂/Al₂O₃ ratio, the crystallization is accelerated substantially. Also, rose-like or lamellar-like morphologies of MCM-22 particles with different sizes can be achieved by changing these reaction parameters. Using this two-step sol–gel route, MCM-22 is able to be well produced in a wide range of the SiO₂/Al₂O₃ ratio from 20 to 100.