聚酰胺酸盐路线制备聚酰亚胺/二氧化硅杂化薄膜的微观结构与性能研究

采用聚酰胺酸成盐的方法合成了聚酰亚胺及聚酰亚胺/二氧化硅杂化薄膜,考察了三乙胺对聚酰亚胺薄膜耐水性的影响,重点研究了聚酰胺酸盐条件下,二氧化硅含量对聚酰亚胺/二氧化硅杂化薄膜的微观形态和力学性能、热稳定性的影响.结果表明:分别在无水和有水条件下,通过聚酰胺酸盐得到的聚酰亚胺薄膜均保持了良好的力学性能.采用上述条件下制备的杂化薄膜,在较高二氧化硅含量下得到的杂化薄膜具有良好的透明性,SEM结果显示其二氧化硅粒子尺寸均为纳米级.此外,这些杂化薄膜还具有良好的力学性能和热性能.     

聚酰亚胺微球掺杂纳米二氧化硅的制备及表征

以4,4’-二氨基二苯醚和均苯四甲酸二酐作为单体,采用非水乳液体系,加入纳米二氧化硅,制备聚酰亚胺微球.本文研究了纳米二氧化硅对聚酰亚胺热性能以及球形形貌、粒径大小的影响.通过红外分析(IR)、热重(TGA)、示差扫描(DSC)、电镜(SEM)、粒度等手段对其进行表征.表征结果显示当纳米SiO2的加入量为0.2g时,此时改性后的聚酰亚胺微球球形形貌良好,粒子表面光滑,呈单分散性,粒径为28.4μm,且失重率为5％时,其在氧气气氛下分解温度高达508℃,呈现高耐热性.     

无机纳米聚酰亚胺复合膜的结构与性能

聚酰亚胺(PI)作为一种功能材料,已广泛用于航空航天和微电子领域。然而聚酰亚胺的耐电晕性差限制其在高温和精密状态下的应用。有机-无机纳米复合和超声辐射可提高材料的耐电晕性。笔者利用超声辐射制备无机纳米二氧化硅/聚酰亚胺复合膜。升温8h,温度至573.15K,得到平均厚度为20~30靘的膜。通过高压实验仪器检测聚酰亚胺复合膜的耐电晕性;通过红外光谱测定聚酰胺酸(PAA)转化为聚酰亚胺的亚胺化程度;通过原子力显微镜表征纳米微粒的特征,包括微粒尺寸、分布、形状和分散性。实验表明,比普通的搅拌方式,超声辐射可使聚酰亚胺膜中的纳米微粒得到更有效的分散,经过纳米二氧化硅杂化的聚酰亚胺复合膜比普通聚酰亚胺膜具有更高的耐电晕性。     

热镀锌钢板纳米二氧化硅改性有机-无机复合膜

研究了热镀锌钢板纳米SiO2改性有机-无机复合膜,研究了不同的纳米SiO2的加入形式对膜层耐蚀性的影响,探讨了该复合膜中钒酸盐的缓蚀作用,该复合膜层具有良好的成膜性能和耐蚀性能.     

原位聚合沉积制备聚苯胺/聚酰亚胺/聚苯胺复合膜

以聚酰亚胺(PI)膜为基体,采用分散聚合原位沉积方法制得聚苯胺/聚酰亚胺/聚苯胺(PANI/PL/PANI)三层复合膜.复合膜表面PANI层外观质量优异,电导率达10~0S/cm.实验结果表明:加入高浓度空间稳定剂(聚乙烯吡咯烷酮,PVP)、调整氧化剂(过硫酸铵,APS)和介质酸(盐酸)的用量可制得表面质量和电导率高的复合膜.较适宜的反应条件为稳定剂质量浓度4%,APS与苯胺(An)的物质的量比为2:4,盐酸浓度为0.5 mol/L.     

耐溶剂聚酰亚胺/陶瓷复合膜的制备及性能表征

采用3,3',4,4'-二苯酮四羧酸二酐(BTDA)、4,4'-二氨基二苯基甲烷(MDA)和4,4'-二氨基联苯(Bz)按一定比例共聚合成了一类新的共聚型聚酰亚胺(PI-BTDA/MDA/Bz),通过调整MDA和Bz的比例制备了4种具有不同化学结构的聚酰亚胺均质膜,测试了这些聚酰亚胺均质膜对水的接触角和在N,N-二甲基甲酰胺中的溶胀性。实验结果表明:BTDA、MDA、Bz的摩尔比为5:4:1时,所得的聚酰亚胺均质膜亲水性最好,且耐溶剂性能最优。以此比例的聚酰胺酸为铸膜液,0.2mm孔径的Al₂O₃陶瓷膜片为支撑体,制备了聚酰亚胺复合膜,并考察了进料温度和进料浓度对复合膜分离性能的影响。     

聚酰亚胺/二氧化硅复合薄膜电学性能的研究

用均苯四甲酸二酐(PMDA)与4,4'-二氨基二苯醚(ODA)为单体,以N,N-二甲基乙酰胺(DMAC)为溶剂,通过超声机械共混法制备聚酰亚胺/二氧化硅(PI/SiO2)复合薄膜,采用红外光谱(FTIR)、扫描电镜(SEM)分别对PI复合薄膜的结构和表面形貌进行了研究表征,通过concept 80宽带介电谱测试系统对复合薄膜电学性能进行了研究。结果表明:在一定的频率下,不同无机纳米粒子含量的复合薄膜中,介电常数和介电损耗角正切随无机纳米质量分数的增加而增大。     

磷钨酸/二氧化硅/磺化聚醚醚酮复合膜的制备、表征与性能

以二氧化硅和磷钨酸改性磺化聚醚醚酮制得一种新型磺化聚醚醚酮复合膜。复合膜中杂多酸仍然保持着Keggin型PW12O430-阴离子的特征结构,二氧化硅和磷钨酸以无定形状态均匀分散于复合膜中。磷钨酸/二氧化硅/磺化聚醚醚酮复合膜的阻醇性能优于Nafion115;质子导电性能随着温度的提高有所增加。复合膜在磷钨酸中具有良好的稳定性。     

聚酰亚胺/带电二氧化硅杂化膜的结构与性能研究

将咪唑基团接枝在二氧化硅纳米颗粒表面上,并在酸性条件下对苯并咪唑基团质子化后,使得二氧化硅纳米颗粒带正电荷,由于同种电荷强烈的静电斥力,以达到二氧化硅纳米颗粒在聚酰亚胺基体中均匀分散,并对二氧化硅纳米颗粒接枝苯并咪唑基团前后进行红外吸收光谱分析和紫外可见光光谱分析,结果证明咪唑基团接枝在二氧化硅表面,最后对制备的纳米复...     

二氧化硅复合膜的制备及其渗透汽化性能

采用溶胶–凝胶法配制了掺杂Zr4+以及未掺杂的2种有机硅态溶胶,以浸渍提拉的方式在已修饰的α-Al₂O₃载体上逐层涂布2种溶胶,并经过煅烧固化制备了二氧化硅复合膜。采用扫描电子显微镜对制备过程中的每一膜层表面形态结构进行表征。将二氧化硅复合膜应用于渗透汽化脱水,考察了不同温度以及不同进料含水率下的渗透汽化性能,并探究了强酸性环境(pH=2)对其性能的影响。实验结果表明:二氧化硅复合膜在75℃对85%(质量分数)异丙醇溶液渗透汽化脱水,其通量可达1 kg/(m²·h),渗透液含水率(质量分数)最高可到99.4%;在不同温度和含水率的条件下,二氧化硅复合膜都能保持良好的分离性能,具有良好的水热稳定性;长时间在强酸性环境(pH=2)中仍能保持稳定的分离性能,具有极强的耐酸性能。     

Pulsed electrodeposition of p-type CuInSe2 thin films

CuInSe₂ thin films have been electrodeposited on conductive glass using cyclic pulse electrodeposition. One cycle consists of consequtively applying potentials E₁ and E₂, each during 10 s and a total of 90 cycles are applied. E₁ is chosen between −0.7 and −0.9 V_SCE while E₂ is fixed at −0.1 V_SCE. The films are annealed in argon and then etched in KCN solution to eliminate remnant secondary phases. The material is characterized employing grazing incident X-rays diffraction, Raman spectroscopy, scanning electron microscopy and energy dispersive scanning spectroscopy. The presence of secondary phases seems to be reduced when compared to films prepared at fixed potentials. The films are crystalline and the overall quality improves by annealing in Ar. Photoelectrochemical tests, Mott–Schottky plots and I–V curves confirm p-type conduction. The diffusion regime imposed by the potential pulses could be responsible for the different morphology and composition of samples prepared with pulsed and potentiostatic electrodeposition.     

SiO2载体对Cu/SiO2催化剂的影响

分别以硅溶胶、气相SiO2、介孔SBA-15分子筛为载体,采用共沉淀法制备了Cu/SiO2催化剂,含活性组分Cu质量分数为25%。运用BET、XRD、H2-TPR、NH3-TPD等对催化剂进行表征。结果表明:以硅溶胶和气相SiO2为载体制得催化剂的Cu物种分散性较差,以SBA-15为载体制得催化剂的Cu物种以高度分散的形式存在,且具有较大的比表面积,较低的还原温度和较大的酸量。     

Properties of adsorbed oxygen on Au/SiO2

Oxygen adsorption on silica-supported gold catalyst from NO₂ and O₂ exposures were investigated by temperature-programmed desorption spectroscopy under a vacuum condition. NO₂ and O₂ exposures of the surface of the catalyst at room temperature gave adsorbed oxygen in atomic state. Adsorbed oxygen penetrated beneath the gold with lower activation energy for NO₂ exposure than for O₂ exposure. Adsorbed oxygen in oxidic state which was desorbed above 600 K altered the surface properties of gold and resulted in the decrease of activation energy for oxygen to penetrate beneath the gold surface.     

Role of SiO2 in synthesis of SiO2-supported CeO2 composites

Pure and SiO₂-supported CeO₂ samples were prepared by Ce(NO₃)₃ decomposition, precipitation, and sol–gel methods in an attempt to study the role of SiO₂ in the synthesis of these materials. During synthesis process, SiO₂ support uniformly adsorbed cerium ions in aqueous solution, preventing nucleation and crystal growth of CeO₂ during the subsequent water evaporation and calcination steps. Uniform adsorption and inhibition were enhanced by NH₄⁺ and, to a larger extent, C₅H₇O₅COO^-. Despite the dispersion of cerium ions on SiO₂ reduced the temperature at which CeO₂ was formed, crystal size and crystallinity of CeO₂ in composites were significantly lower than that of pure CeO₂ sample prepared by the same synthesis method and at the same temperature. Composites were quite stable upon increasing the temperature from 400 to 800?°C. Visible light absorption, reduction, and photocatalytic activity characteristics of CeO₂ were improved upon dispersion on SiO₂. This work can help synthetize supported oxides with high activity and thermal stability.     

超细二氧化硅纤维/橡胶复合材料的结构与性能研究

通过静电纺丝技术制备了直径为300~500 nm的超细二氧化硅纤维,制备的纤维进一步研磨和超声处理得到二氧化硅短纤维,然后将其填充到胎面胶中,分析了不同取向的二氧化硅纤维对胎面胶物理机械性能与动态力学性能的影响。结果表明：二氧化硅纤维在胎面胶基体中有着良好的分散,可以明显提高复合材料的100%定伸模量。在动态性能上,当纤维取向方向与分子链方向一致时,其60~80oC损耗因子最小。当纤维取向方向与分子链方向垂直时,0~-20oC损耗因子最大。因此该二氧化硅纤维作为一种新型增强填料在胎面胶上有着良好的应用前景。     

Preparation and characterization of TiO2–SiO2 nano-composite thin films

TiO₂ nanocrystalline particles dispersed in SiO₂ have been prepared by the sol-gel method using titanium- and silicon-alkoxides as precursors. Nano-composite thin films were formed on the glass substrates by dip-coating technique and heat treated at temperatures up to 500 °C for 1 h. The size of the TiO₂ nanocrystalline particles in the TiO₂–SiO₂ solution ranged from 5 to 8 nm. The crystalline structure of TiO₂ powders was identified as the anatase phase. As the content of SiO₂ increased, the anatase phase tended to be stabilized to higher temperature. TEM results revealed the presence of spherical TiO₂ particles dispersed in a disk-shaped glassy matrix. Photocatalytic activity of the TiO₂–SiO₂ (1:1) thin films showed decomposition of 95% of methylene blue solution in 2 h and a contact angle of 10°. The photocatalytic decomposition of methylene blue increased and the contact angle decreased with the content of TiO₂ phase. TiO₂–SiO₂ with the molar ratio of 1:1 showed a reasonable combination of adhesion, film strength, and the photocatalytic activity.     

锌掺杂多孔SiO_2/TiO_2薄膜制备及光催化性能研究

锌掺杂多孔SiO2/TiO2(多孔Zn-SiO2/TiO2)复合薄膜自清洁玻璃以含聚乙二醇的钛醇盐和硅醇盐的复合溶胶前驱体通过浸渍提拉法制备。结果表明,在TiO2薄膜中添加SiO2可抑制TiO2晶粒长大,并提高TiO2薄膜的亲水性;随着聚乙二醇添加量的增加,锌掺杂多孔SiO2/TiO2薄膜的孔隙增多,表面积增大;经500℃煅烧的多孔Zn-SiO2/TiO2复合薄膜中,TiO2主要为催化效率高的锐钛矿相;多孔Zn-SiO2/TiO2复合薄膜表观光催化降解速率明显高于未掺锌多孔SiO2/TiO2薄膜。     

Protective properties of SiO2 with SiO2 and Al2O3 nanoparticles sol-gel coatings deposited on FeCrAl alloys

Five layer SiO₂ coatings containing SiO₂ or Al₂O₃ nanopowders were deposited on FeCrAl alloy support by sol-gel method. Studies of protective properties of the coatings were carried out during high temperature cyclic oxidation. Changes in surface topography, structure and chemical composition of the surface layer of FeCrAl alloy were investigated. It has been shown that the type of nanofillers present in the SiO₂ coating (about 2.5?wt%) affects morphology of Al₂O₃ growing scale and determines the heat resistance of FeCrAl alloy. The lowest relative mass change (approx. 1.3%) after 10 oxidation cycles in air at 900?°C (one cycle = 12?h) was measured for the samples with coatings containing hydrophilic nanosilica (Aerosil 380) as filler. The protective efficiency of the coatings in the process of high-temperature oxidation is from 66% to 85%. The thickness of the formed scale and the value of the parabolic rate constant depend on the type of nanopowder in the coating.     

二氧化硅超细短纤维/氯丁橡胶复合材料的结构与性能

利用静电纺丝技术制备二氧化硅超细短纤维(n-SF),采用偶联剂KH-570对其进行改性,再制备改性n-SF(n-MSF)/氯丁橡胶(CR)复合材料,并对复合材料的结构和性能进行研究。结果表明:n-MSF在CR基体中分散均匀,与CR界面结合良好;加入适量的n-MSF,复合材料的定伸应力、撕裂强度及抗溶胀能力明显提高,动态力学性能有所改善。     

Properties of SiO2 thin films prepared by anodic oxidation under UV illumination and rapid photothermal processing

Anodic oxidation under ultraviolet (UV) illumination and rapid photothermal processing technique used for high quality oxide preparation in terms of device surface passivation and gate or tunnel dielectrics are reported. A number of samples of SiO₂ thin films were prepared using this technique. It is shown that anodic oxidation under UV illumination followed by rapid photothermal processing (450 °C, 15 s) in the inert ambient yields the best optimization of the SiO₂ thin films properties. Avoiding high temperature process should result in a better performance of the semiconductor devices. Anodic oxidation under UV illumination at low temperature and post-oxidation photothermal processing can be a possible alternative to the furnace growth silicon oxide; not only because of the low temperature process, but also because this technology essential improves the oxides properties.