(PTMO+PDMS)/SiO_2杂化材料的制备与表征

以羟基封端的聚二甲基硅氧烷(PDMS)、正硅酸乙酯(TEOS)为主要原料,加入一定质量的功能化聚四氢呋喃(PTMO),通过溶胶-凝胶法制备出均匀透明的(PTMO+PDMS)/Si O2杂化材料。采用红外吸收光谱、紫外-可见光透过光谱以及扫描电子显微镜对制备的材料进行了表征。结果表明,所制得的杂化材料以化学键相结合,两相分散均匀,可见光区透光率高,相容性好。     

Sol-gel synthesis of hybrid materials

Sol-gel chemistry allows the synthesis of hybrid organic-inorganic materials. Organic molecules can be used as complexing ligands to provide a chemical control over hydrolysis and condensation reactions, leading to the formation of stable suspensions of nanoparticles. They can also be trapped within the sol-gel matrix in order to provide some optical properties such as photochromism. When chemically bound to the oxide network via Si-C bonds they lead to hybrid nanocomposites that offer new possibilities in the field of materials science. Even biospecies, such as enzymes or antibodies, can be trapped within sol-gel matrices in order to make bio-sensors or bio-catalysts.     

有机/纳米二氧化钛杂化材料的合成与表征

采用溶胶 -凝胶聚合法 ,制备了稳定的纳米二氧化钛 /有机聚合物改性的杂化材料。研究了不同的反应方法对该杂化材料的粒子形状、溶液稳定性和光折射率的影响。红外光谱和透射电镜分析表明 :该材料是由内部的Si -O -Ti键和表面有机聚合物组成的 ,并且有纳米尺寸的结构。该杂化材料在甲苯 /丁醇组成的混合溶剂中具有良好的稳定性     

Synthesis and properties of a novel isomeric polyimide/SiO2 hybrid material

A novel isomeric polyimide/SiO₂ hybrid material was successfully prepared through sol–gel technique, and its structure, thermal properties and nano-indenter properties were investigated. First, 3-[(4-phenylethynyl)phthalimide]propyl triethoxysilane (PEIPTES) was successfully synthesized, its structure was characterized by elemental analysis, FT-IR and ¹³C NMR. The researches on solubility and thermal properties of PEIPTES show that it can be used for modifying nano-SiO₂ precursor. Nano-SiO₂ precursor was synthesized by tetraethoxysilane (TEOS) through sol–gel technique. Then the PEIPTES solution and the nano-SiO₂ precursor were mixed for 6 h to let the PEIPTES molecules react with the nano-SiO₂ precursor, and modified nano-SiO₂ precursor was obtained. The modified reaction was confirmed by the analyses of FT-IR. At last, isomeric polyimide/SiO₂ hybrid material was produced by using isomeric polyimide resin solution and the modified nano-SiO₂ precursor after heat treatment process. The structure analysis by SEM indicated that SiO₂ particles dispersed in isomeric polyimide matrix homogeneously with nanoscale. Thermogravimetric analyzer, dynamic mechanical thermal analyzer and nano-indenter XP was employed to detect the properties of the materials, the results demonstrated that isomeric polyimide/SiO₂ hybrid material has much better thermal properties and nano-indenter properties than those of isomeric polyimide. It is confirmed that PEIPTES acts as a bridge between the SiO₂ particles and the isomeric polyimide matrix in the hybrid material, because the ethoxyl of PEIPTES could participate in the hydrolyzation and condensation to form chemical bond with SiO₂ particles and its phenylethynyl group could take part in the cross-curing reaction of isomeric polyimide.     

Crystallization behavior of PA6/SiO2 organic–inorganic hybrid material

Poly 2-hydroxy propylmethacrylate-methyl methacrylate/SiO₂ (PHPMA-MMA/SiO₂), an active composite was used to synthesize polyamide-6/SiO₂ (PA6/SiO₂) organic–inorganic hybrid materials via blending method. X-ray diffraction analysis (XRD) results showed that the addition of PHPMA-MMA/SiO₂ composite induced PA6 to transit from α to γ crystal form. The nonisothermal crystallization kinetics of PA6 and PA6/SiO₂ hybrid materials was investigated by differential scanning calorimetry (DSC). Jeziorny method derived from Avrami analysis and a method developed by Liu were employed to describe the nonisothermal crystallization process of PA6 and PA6/SiO₂ hybrid materials. Based on our experimental data, if the relative degree of crystallinity was approximately 60% or more, the Jeziorny method was not valid to describe the nonisothermal crystallization process, while Liu method was successful to describe the whole nonisothermal crystallization process. When X(t) was below about 60%, the crystallization rates of PA6 and PA6/SiO₂ hybrid materials were very approximate, but when X(t) was approximately 60% or more, the crystallization rate of PA6 was quicker than that of PA6/SiO₂ hybrid materials. Moreover, the addition of PHPMA-MMA/SiO₂ composite decreased the crystallization activation energy ΔE calculated by Kissinger equation because of the γ transition.     

Sol-gel synthesis and characterization of nanostructured TiO2/gamma-Al2O3 composite membranes

Nanostructured TiO2/gamma-Al2O3 composite membranes with various compositions were prepared by sol-gel method. The structural and textural properties of the composite membranes could be modified by the mixing ratio of boehmite sol and titania sol, and calcination temperature. The existence of alumina in the composite membranes retarded anatase-to-rutile phase transformation, resulting in stabilization of textural properties. Defect-free composite membranes were confirmed by gas permeation test.     

Effect of TiO2 morphology on in vitro bioactivity of polycaprolactone/TiO2 nanocomposites

TiO₂ nanostructures with different morphologies (spherical, tube, leaf-like and flower-like particles) were synthesized via a facile hydrothermal process. Polycaprolactone (PCL)/10 vol.% TiO₂ nanocomposites were prepared by solvent casting methods. In vitro bioactivity of the nanocomposite films was examined by immersion in the simulated body fluid (SBF) for up to 28 days. It was found that the morphology of titania nanostructures significantly influence the in vitro bioactivity of PCL/TiO₂ nanocomposites. This observation was attributed to the amount of anatase phase and the specific surface area of the TiO₂ nanostructures, which provide high surface exposure to SBF.     

无定形介孔SiO_2纳米粉体的仿生合成及表征(英文)

以酵母细胞为模板,采用共沉淀法制备了具有介孔结构的无定形SiO2纳米粉体。采用X射线衍射(XRD)测试出合成的材料为无定形结构,通过氮气吸附-脱附测试证明样品中含有介孔结构,并且样品的比表面积为443.18m2/g,BJH吸附平均孔径为6.24nm。样品的介孔结构也通过TEM得到证实。采用红光光谱测试分析了样品的化学键的键链情况。最后对其合成机理进行了分析,并画出了合成机理的简单模拟图。     

Sol-gel synthesis and characterization of the photocatalyst BaCo1/3Nb2/3O3

The photocatalyst BaCo_1/3Nb_2/3O₃ has been synthesized at 750°C by using a sol-gel process, and the surface area is 19.70 m²/g. While the surface area of the powder synthesized by using a solid state reaction process is 2.2 m²/g. It was characterized by X-ray diffraction, scanning electron microscopy(SEM), UV-vis diffuse reflectance spectroscopy, Raman scattering spectroscopy and the measurement of the photocatalytic activity in evolving H₂ from CH₃OH/H₂O solution with the Pt co-catalyst under visible light irradiation. From the SEM image, BaCo_1/3Nb_2/3O₃ powder calcined at 750°C is dispersive, and the average particle size is about 30 nm. Raman scattering spectrum at room temperature shows that, due to the different ionic radius of the Co²⁺ and Nb⁵⁺ ions, BaCo_1/3Nb_2/3O₃ may has a distorted perovskite structure. Under visible light irradiation (λ > 420 nm), the formation rate of H₂ evolution from CH₃OH/H₂O solution with the 0.5 wt% Pt co-catalyst is about 18.1 μmol/h·gcat. for the photocatalyst BaCo_1/3Nb_2/3O₃, much higher than that of BaCo_1/3Nb_2/3O₃ powder synthesized by the solid state reaction process.     

硅酸盐氧基磷灰石的溶胶凝胶法制备与表征

为了提高电导率,以溶胶-凝胶法制备了硅酸盐氧基磷灰石.通过TG-DTA、XRD和IR分析,研究了从凝胶转变为硅酸盐氧基磷灰石过程中凝胶焙烧温度的影响.结果表明,制备Sr2La8(SiO4)6O2、La9.33(SiO4)6O2和La10(SiO4)6O3时凝胶的焙烧温度分别为850、950℃和950℃;间隙氧可能诱发晶体结构扭曲,晶胞体积变大.通过IR和XRD分析,证实了在La9.33(SiO4)6O2和La10(SiO4)6O3磷灰石中间隙氧的存在.     

C/C复合材料的非晶SiO_2涂层制备及其生物活性

以正硅酸乙酯(TEOS)为前驱体,N_2为载气,在C/C复合材料表面通过低压化学气相沉积(LPCVD)得到非晶SiO_2涂层。研究了沉积温度对涂层成分、涂层形貌和沉积速率的影响。通过XRD、XPS、FTIR、SEM和EDS等测试手段,对涂层的成分、微观形貌以及模拟体液浸泡后材料的生物活性进行了表征和分析。实验结果表明:涂层的主要物相为非晶SiO_2;模拟体液浸泡至35天,样品表面生成类骨羟基磷灰石,与未涂层的C/C复合材料相比,表明非晶SiO_2涂层具有良好的生物活性。随着沉积温度的增加,沉积速率增大,涂层包覆更加完整;SiO_2颗粒由不规则形状转变为规则的球形,最后转变成多边形。     

光敏性杂化SiO2波导薄膜的制备、表征及应用

利用有机/无机杂化方法制备了光敏性溶胶-凝胶（sol-gel）SiO2材料，在预生长了18μm厚的SiO2上包层的硅基片上旋涂成膜。经前烘、紫外曝光、后烘的薄膜在5μm×5μm的扫描范围内的表面粗糙度只有0．266nm，表面起伏度只有0．336nm。利用紫外光直写技术，制作出条形波导器件。SEM照片表明波导端面形状较好，侧壁陡直。对1×4多模干涉型分束器进行初步的通光测试，观察到分光效果较好的近场输出图像。     

Sol-gel synthesis and characterization of barium titanate powders

A simple aqueous sol-gel route has been refined to prepare yttrium-doped barium titanate powders. Thermal decomposition of the fabricated gel was studied by means of DTA/TGA measurements. The precursor gel was intermediate calcined at 600 °C, and the final synthesis products were characterized by IR spectroscopy, X-ray powder diffraction and scanning electron microscopy. The barium titanate obtained from the calcination of the gel at 1300 °C was a tetragonal phase, and showed a positive temperature coefficient of resistivity (PTCR) effect which depends on sample cooling rate during the final heat treatment.     

Sol-gel synthesis, characterization and impedance studies of lithium borosilicate glass

Densified xerogels of lithium borosilicate (LBS) were synthesized through sol-gel process by varying modifier to formers (m/f) ratios. XRD and FTIR spectra were recorded for dried LBS gel samples heat-treated at different temperatures and the gel to glass to crystalline changes were studied. Also, all LBS samples were characterized by XRD, FTIR and DSC techniques. Impedance measurements were made on all LBS samples at different temperatures and the impedance data were analyzed using Boukamp equivalent circuit software. Conductivity of each m/f ratios of LBS samples were calculated from the analyzed impedance data and 20% Li₂O-80% [0.2 B₂O₃ + 0.8 SiO₂] composition showed the best conductivity σ = 8.83 (±0.02) × 10⁻⁸ Scm⁻¹ at 443 K. The activation energy (E_a) is obtained from the temperature dependent of conductivity data fitted to Arrhenius equation and it is found to be 0.64 eV (±0.02). The observed variation of conductivity with m/f ratios of LBS samples was explained using weak electrolyte model.     

聚酰亚胺/二氧化硅杂化材料取向稳定性的研究

以5,5'-(六氟异丙基)-二-(2-氨基苯酚)(6FHP)和4,4'-(六氟异丙基)-苯二酸酐(6FDA)或均苯四甲酸酐(PMDA)为单体,合成了含氟聚酰亚胺.采用溶胶-凝胶法得到了不同无机组分含量的热稳定性高的杂化材料,测定了它们的电光系数,其电光系数γ33在测试持续500min后保持其初始值的95%以上,说明材料可用于电光器件化.通过测定膜的极化前后的紫外-可见光谱,得到了取向发色团的序参数Ф(0.27～0.38),经60h序参数几乎不变.通过一维刚性气体模型研究了材料的宏观二阶非线性光学系数χ(2),结果表明材料的极化效率较高,设计合理,有较好的取向稳定性.     

新型PMMA/SiO_2/DR1非线性光学杂化材料的制备及表征

通过溶胶-凝胶法将硅烷染料DR1ASD、含硅氧烷PMMA和TEOS在酸催化条件下共水解-缩合制备了新型非线性光学杂化材料PMMA/SiO2/DR1,并运用FT-IR、SEM、UV-vis、DSC/TG和UV-vis等测试方法对其结构和性能进行表征.测试结果表明:杂化材料中有机相和无机相之间通过共价键结合,无相分离出现;杂化材料的玻璃化转变温度(Tg)和热分解温度(Td)分别达到165℃和405℃;电晕极化后杂化材料具有较高的生色团取向有序度(Φ=0.238),并表现出良好的取向稳定性,80℃条件下3h后依然有初始值的79%.     

SiO2-Al2O3干凝胶的制备与性能研究

采用二步酸碱催化溶胶-凝胶和常压干燥法,制备了低密度多孔xSiO2-(1-x)Al2O3干凝胶,其中摩尔比x分别取0.9、0.8、0.7和0.6.SiO2凝胶按照n(正硅酸乙酯(TEOS)):n(H2O):n(无水乙醇):n(HCl):n(氨水)=1: 4:7:7.5×10-4:0.0375制备,主要作为二元复合氧化物的网络骨架.Al2O3由廉价的Al(NO3)3·9H2O与NH4OH反应制得.采用BET、XRD、IR、SEM和TEM等实验手段,对xSiO2-(1-x)Al2O3干凝胶在300、600、900、1200℃4个热处理温度下的组织结构进行了对比和分析.结果表明,最终的二元干凝胶是由纳米颗粒组成的非晶网络与Al2O3晶体共同构成的纳米多孔结构,具有高的比表面积和窄的孔径分布.该复合干凝胶中,Al2O3进入SiO2骨架中,形成一定数量的Si-O-Al键,并随着Al含量的增加而增多.其中的Al2O3随着温度的升高,经历γ-AlOOH、γ-Al2O3,最终完全转化成α-Al2O3,SiO2则始终以非晶态形式存在.由于干凝胶中Al2O3的存在,大大提高了材料的热稳定性.     

溶胶—凝胶法制备TiO2—SiO2复合薄膜的研究

采用溶胶－凝胶方法在单晶Ｓｉ基片上制备了ＴｉＯ２－ＳｉＯ２复合薄膜，研究了溶剂、ｐＨ值对先体溶液成胶时间的作用，溶液的浓度、甩胶时的旋转速度、涂覆层数以及热处理温度对薄膜厚度、光学性能的影响。薄膜的折射率随温度增大，其主要贡献来自于薄膜中结构的变化。并测量了薄膜的Ｉ－Ｖ、Ｃ－ｆ特性，由于薄膜中的热击穿效应而使得ＴｉＯ２含量较高的薄膜２的Ｉ－Ｖ呈非线性变化。     

PDMS/SiO2杂化材料的合成与性能研究

采用草酸作为催化剂,通过溶胶-凝胶(Sol-Gel)反应制得了透明的块状聚二甲基硅氧烷/SiO2有机-无机杂化材料,并采用FTIR、TG等方法对所制备的杂化材料进行了分析表征,考核了杂化材料的硬度.结果表明:所制备的杂化材料中的硬度随PDMS用量、分子量以及H2O/TEOS的摩尔比的增加而降低,其热重损失率随PDMS用量的增加而下降.     

溶胶-凝胶法制备SiO2薄膜的工艺研究

以正硅酸乙酯为前驱体、乙醇为溶剂,通过酸催化,采用溶胶-凝胶法制备SiO2薄膜,通过正交实验确定最佳工艺方案,并讨论影响SiO2薄膜结构和性质的主要因素,研究了最佳配方siO2薄膜的表面形貌、光学性能和力学性能等.结果表明,影响光学性能的主要因素是正硅酸乙酯和水;影响显微硬度的主要因素是乙醇;膜层结构为非晶态;薄膜具有增透效果并可提高试样的抗弯强度.