电化学制备亚微米氧化铝有序多孔膜方法研究

采用电化学阳极氧化法制备亚微米氧化铝有序多孔膜 ,研究了铝电极预处理过程、扩孔时间、阳极氧化时间和阳极氧化电压对亚微米氧化铝有序多孔膜孔径、孔密度以及孔排列有序性的影响规律 ,并且建立了一个理想模型来探讨亚微米氧化铝多孔膜的生长过程     

电化学制备亚微米氧化铝有序多孔膜方法研究

采用电化学阳极氧化法制备亚微米氧化铝有序多孔膜,研究了铝电极预处理过程、扩孔时间、阳极氧化时间和阳极氧化电压对亚微米氧化铝有序多孔膜孔径、孔密度以及孔排列有序性的影响规律,并且建立了一个理想模型来探讨亚微米氧化铝多孔膜的生长过程.     

电化学制备亚微米氧化铝有序多孔膜方法研究

采用电化学阳极氧化法制备亚微米氧化铝有序多孔膜，研究了铝电极预处理过程、扩孔时间、阳极氧化时间和阳极氧化电压对亚微米氧化铝有序多孔膜孔径、孔密度以及孔排列有序性的影响规律，并且建立了一个理想模型来探讨亚微米氧化铝多孔膜的生长过程。     

氧化铝、氧化钛多孔膜的阳极氧化制备与微结构比较

采用阳极氧化法分别获得了纳米结构的氧化铝多孔膜和氧化钛多孔膜。对多孔膜的微结构、形貌、晶相等进行了检测与分析;系统研究了阳极氧化电压对纳米孔孔径的影响,分析了金属箔片退火、两步阳极氧化对纳米孔有序度和孔径均匀性的影响;对阳极氧化过程中出现的新颖的上下双层和内外双层多孔膜形貌进行了分析和讨论。初步获得了纳米多孔膜的形成机理,阳极氧化铝、氧化钛纳米多孔膜在制备、微结构等方面存在许多共同点。     

基于选区激光熔化工艺的低弹性模量多孔材料的研究

依据人体骨骼结构的特点及力学性能要求,基于选区激光熔化工艺使用Ti6Al4V粉末,结合密质骨和松质骨的特点开发低弹性模量的多孔材料。通过与密质骨等密度原则确定的44.92%的孔隙率,并仿制松质骨的多孔结构建立模型,研究了不同能量密度(50 J/mm²、51.8 J/mm²)、不同孔径大小(500μm、1 000μm、1 500μm)对多孔材料相关性能的影响。研究表明,基于前述条件制备的体相多孔材料,成形性较好,孔径均匀可控,孔道贯通,外形尺寸可控;试样的孔隙率随孔径的增大而增大,小孔径下500μm的试样更接近设计的孔隙率参数;随着试样孔径的增大,孔径与抗拉强度成正相关关系,但弹性模量逐渐减小;试样实体部分成形质量较好,拉伸测试断口表明基本不存在裂纹等应力缺陷;各试样均不同程度地出现了熔化后的凝固缩孔,为粉末熔化凝固自然特性;多孔结构均能实现低弹性模量的设计要求,51.8 J/mm²能量密度下成形的试样在孔径500μm下的抗拉强度为70 MPa,弹性模量为18 GPa,更接近人体密质骨的性能。     

多孔阳极氧化铝模板的制备

以多孔阳极氧化铝膜为模板制备纳米结构材料具有独特的优越性,得到了广泛的关注。介绍了多孔阳极氧化铝膜的形成机理、结构类型和在草酸溶液中制备多孔氧化铝模板的工艺。在本实验中,使用高纯铝片(99.99%)和0.3 mol/L浓度的草酸,利用电化学二次阳极氧化法制备出多孔阳极氧化铝模板,用SEM对其形貌进行了观测,得到的模板孔径在50～70 nm,孔间距约为100 nm。     

Pechini法制备TiO_2薄膜及其在染料敏化太阳电池中的应用

用Pechini法在FTO导电玻璃上制备不同厚度的TiO2薄膜,并组装成染料敏化太阳能电池。XRD结果表明,在450℃退火1h得到了主相为锐钛矿的TiO2。SEM结果表明,TiO2薄膜表面疏松多孔,粒径均匀,厚度在6~15μm。紫外-可见光谱分析表明,TiO2薄膜染料的吸附量随薄膜厚度的增加而增加。光电性能研究表明,在0.005W/cm2的弱光照下,膜1(厚6μm)和膜2(厚15μm)光阳极的光电转换效率分别为6.85%和11.83%;在0.1 W/cm2的模拟标准太阳光照下,膜1和膜2光阳极的光电转换效率分别为1.72%和2.39%。     

新型声表面波湿度传感器

为解决目前常用电容式湿度传感器存在的误差较大和一致性较差的问题,提出了采用常压化学气相淀积(APCVD)法制备的多孔SiO2膜作为吸湿材料的乐甫波声表面波(SAW)传感器感知湿度。基片采用42.75°旋转Y轴切割石英材料,乐甫波传播方向为[0°,132.75°,90°],SiO2湿敏膜厚度为0.5μm。实验结果表明:此湿度传感器灵敏度约为62 kHz/RH%,在相对湿度为50%时,最大湿滞约3%。测得的湿敏特性和迟滞特性表明,乐甫波声表面波湿度传感器线性度较好,实验证实该湿度传感器具有很好的应用前景。     

多孔氧化铝模板的制备及性质研究

多孔氧化铝由于具有规则的纳米多孔结构,是制备各种纳米材料的良好模板,因此,研究多孔氧化铝的制备和物理性质具有重要的意义.采用阳极氧化方法制备了多孔氧化铝有序孔洞阵列,通过场发射扫描电镜(SEM)和X射线衍射(XRD)观测了样品的表面、截面的形貌和晶态结构,分析了样品的透射光谱性质.结果表明,制备的多孔氧化铝模板的孔洞分布有序,孔径大小均匀,严格垂直底面;模板具有非晶态结构,在可见光和红外波长范围内具有较高的透射性能.     

用氧化多孔硅方法制备厚的Si02膜及其微观分析

用氧化多孔硅的方法来制备厚的SiO2成本低,省时.氧化硅膜的厚度,表面粗糙度和组分这三个参数,对波导器件的性能有重要影响,扫描电子显微镜(SEM)、原子力显微镜(AFM)和俄歇分析得到：氧化的多孔硅的膜厚已达21.2μm;表面粗糙度在1nm以内,Si和O的组分比为1:1.906.这些结果表明,用氧化多孔硅方法制备的厚SiO2膜满足低损耗光波导器件的要求.     

Hierarchical Directed Self‐Assembly of Diblock Copolymers for Modified Pattern Symmetry

Block copolymer lithography exploiting diblock copolymer thin films is promising for scalable manufacture of device‐oriented nanostructures. Nonetheless, its intrinsic limitation in the degree of freedom for pattern symmetry within hexagonal dot or parallel line array greatly diminishes the potential application fields. Here, we report multi‐level hierarchical self‐assembled nanopatterning of diblock copolymers for modified pattern symmetry. Sequential hierarchical integration of two layers of diblock copolymer films with judiciously chosen molecular weights and chemical composition creates nanopatterned morphology with modified pattern symmetry, including sparse linear cylinder or lamellar arrays. Internal structure of the hierarchically patterned morphology is characterized by grazing‐incidence small‐angle X‐ray scattering throughout the film thickness. Pattern transfer of the modified nanopattern generates linear metal nanodot array with uniform size and regular spacing as a typical example of functional nanopatterned structures.     

Nanoporous Low‐κ Polyimide Films via Poly(amic acid)s with Grafted Poly(ethylene glycol) Side Chains from a Reversible Addition–Fragmentation Chain‐Transfer‐Mediated Process

Thermally‐initiated living radical graft polymerization of poly(ethylene glycol) methyl ether methacrylate (PEGMA) with ozone‐pretreated poly[N,N′‐(1,4‐phenylene)‐3,3′,4,4′‐benzophenonetetra‐carboxylic amic acid] (PAmA) via a reversible addition–fragmentation chain‐transfer (RAFT)‐mediated process was carried out. The chemical compositions and structures of the copolymers were characterized by nuclear magnetic resonance (NMR) spectroscopy, thermogravimetric analysis (TGA), X‐ray photoelectron spectroscopy (XPS), and molecular weight measurements. The “living” character of the grafted PEGMA side chains was ascertained in the subsequent extension of the PEGMA side chains. Nanoporous low‐dielectric‐constant (low‐κ) polyimide (PI) films were prepared by thermal imidization of the PAmA graft copolymers under reduced argon pressure, followed by thermal decomposition of the side chains in air. The nanoporous PI films obtained from the RAFT‐mediated graft copolymers had well‐preserved PI backbones, porosity in the range of 5–17 %, and pore size in the range of 30–50 nm. The pores were smaller and the pore‐size distribution more uniform than those of the corresponding nanoporous PI films obtained via graft copolymers from conventional free‐radical processes. Dielectric constants approaching 2 were obtained for the nanoporous PI films prepared from the RAFT‐mediated graft copolymers.     

Synthesis of Amphiphilic Copolymers of Poly(ethylene oxide) and Poly(ϵ‐caprolactone) with Different Architectures,and Their Role in the Preparation of Stealthy Nanoparticles

Well‐defined copolymers of biocompatible poly(?‐caprolactone) (PCL) and poly(ethylene oxide) (PEO) are synthesized by two methods. Graft copolymers with a gradient structure are prepared by ring‐opening copolymerization of ?‐caprolactone (?CL) with a PEO macromonomer of the ?CL‐type. The ?CL polymerization is initiated by a PEO macroinitiator to prepare diblock copolymers. These amphiphilic copolymers are used as stabilizers for biodegradable poly(D,L ‐lactide) (PLA) nanoparticles prepared by a nanoprecipitation technique. The effect of the copolymer characteristic features (architecture, composition, and amount) on the nanoparticle formation and structure is investigated. The average size, size distribution, and stability of aqueous suspensions of the nanoparticles is measured by dynamic light scattering. For comparison, an amphiphilic random copolymer, poly(methyl methacrylate‐co‐methacrylic acid) (P(MMA‐co‐MA)), is synthesized. The stealthiness of the nanoparticles is analyzed in relation to the copolymer used as stabilizer. For this purpose, the activation of the complement system by nanoparticles is investigated in vitro using human serum. This activation is much less important whenever the nanoparticles are stabilized by a PEO‐containing copolymer rather than by the P(MMA‐co‐MA) amphiphile. The graft copolymers with a gradient structure and the diblock copolymers with similar macromolecular characteristics (molecular weight and hydrophilicity) are compared on the basis of their capacity to coat PLA nanoparticles and to make them stealthy.     

湿度和频率对湿敏元件电学特性的影响

在印有梳状电极的石英玻璃表面涂覆氧化钛纳米薄膜制备湿敏元件,研究不同湿度、不同频率下的电学特性。结果表明,随着湿度的增大,湿敏元件的电阻值、阻抗值减小,电容增大;当湿度一定时,电阻值、电容值都随频率的增大而减小;工作频率为0.01 kHz、相对湿度高于40%时,具有较好的湿敏特性。实验说明湿敏元件中不仅电子、离子浓度发生变化,材料的极化也发生了变化。     

Ferritin–Polymer Conjugates: Grafting Chemistry and Integration into Nanoscale Assemblies

Controlled free radical polymerization chemistry is used to graft polymer chains to the corona of horse spleen ferritin (HSF) nanocages. Specifically, poly(methacryloyloxyethyl phosphorylcholine) (polyMPC) and poly(PEG methacrylate) (polyPEGMA) chains are grafted onto the nanocages by atom transfer radical polymerization (ATRP), in which the molecular weight of the polymer grafts is controlled by the monomer‐to‐initiator feed ratio. PolyMPC and polyPEGMA‐grafted ferritin show a generally suppressed inclusion into diblock copolymer films relative to native ferritin, and the polymer coating is seen to mask the ferritin nanocages from antibody recognition. The solubility of polyPEGMA‐coated ferritin in organic solvents enables its processing with polystyrene‐block‐poly(ethylene oxide) copolymers, and selective integration into the PEO domains of microphase‐separated copolymer structures.     

基于纳米多孔薄膜的对称平面光波导湿度传感器

通过在对称平面玻璃光波导上下表面各制备一层纳米多孔TiO2薄膜,形成了一种简单新颖的光学湿度传感器。其原理为,导波光在平面对称光波导中的传播损失依赖于纳米多孔Ti02薄膜的平均折射率,后者依赖于薄膜内部的水分子吸附量,而薄膜的水分子吸附量随着周围相对湿度的变化而变化,通过实时测量导波光传播损失的变化就能够感知外围的相对...     

Determining Protein Size Using an Electrochemically Machined Pore Gradient in Silicon

Porous silicon films displaying a distribution of pore dimensions can be generated by electrochemically etching silicon in aqueous ethanolic HF using an asymmetric electrode configuration. The median pore size and breadth of the size‐distribution in the film can be set by adjusting the HF concentration, current density, and position of the counter electrode relative to the silicon electrode. Films with pore sizes in the range of a few nanometers are used as size‐exclusion matrices to perform an on‐chip determination of macromolecule dimensions. The test molecule used in this study is bovine serum albumin (BSA). Optical reflectivity spectra of the thin porous Si films display distinctive shifts in the Fabry–Perot fringes in regions of the film where the pore dimensions are larger than a critical size, interpreted to be the characteristic dimensions of the protein. Gating of the protein in and out of the porous films is demonstrated by adjustment of the solution pH below and above the pI (isoelectric point) value, respectively.     

Morphological Control of Nanoporous Films by the Use of Functionalized Cyclodextrins as Porogens

Porous cyclic silsesquioxane (CSSQ) thin films containing nanopores (～ 2 nm) with low dielectric constant (k < 2.2), have been prepared by using various kinds of cyclodextrin (CD) derivatives as porogenic materials. The pore structure, including average pore size and interconnectivity, can be controlled by changing the functional groups of the cyclodextrin derivatives. The pore structure is found to be strongly related to the affinity of the functional groups between CD molecules. The electrical and mechanical properties of the porous thin films were monitored in order to determine the relationship between the pore structure and film properties. The mechanical properties of porous low‐k thin films (total porosity ～ 30 %) prepared with CD derivatives are found to be correlated with the pore interconnection length. The longer the deduced interconnection length in the thin film, the worse the mechanical properties (such as hardness and modulus) of the thin film, even though the porogen‐induced pore diameters are very small (～ 2 nm).     

溅射制作埋嵌电阻的TaN薄膜电阻率的控制

文章介绍的是由射频（RF）溅射反应沉淀制备的TaN薄膜,以及在各种N2/Ar气流比例和工作压力下测试其电阻率变化。从X射线衍射（X-RD）图像和四点探针测试仪测试的TaNx薄膜方块电阻来看。研究发现,TaNx薄膜电阻率发生突变的原因主要是由于N2分压的作用而使TaNx薄膜晶体结构发生了变化。当六边形结构的TaN薄膜变成面心立方行结构时,薄膜电阻从16Ω/sq增加到1396Ω/sq。但是,在晶体结构不变和一定的工作压力范围内,我们能把TaN薄膜的电阻率控制在69Ω/sq到875Ω/sq范围内。在扫描电子显微镜（SEM）成像中,晶粒尺寸随着工作压力的增加将会有所减小。     

The Influence of Film Thickness on the Transparency and Conductivity of Al-Doped ZnO Thin Films Fabricated by Ion-Beam Sputtering

To evaluate the influence of film thickness on the structural, electrical, and optical properties of Al-doped ZnO (AZO) films, a set of polycrystalline AZO samples with different thickness were deposited on glass substrates by ion-beam sputtering deposition (IBSD). X-ray diffraction (XRD), atomic force microscopy (AFM), energy-dispersive x-ray spectroscopy (EDS), four-point probe measurements, and spectrophotometry were used to characterize the films. XRD showed that all the AZO films had preferred c-axis orientation. The ZnO (110) peak appeared, and the intensity increased, with increasing thickness. All the samples exhibited compressive intrinsic stresses. AFM showed that the grain size along with the root-mean-square (RMS) roughness increased with increasing thickness. The decrease of resistivity is due to the corresponding change in grain size, surface morphology, and chemical composition. The average optical transmittance of the AZO films was over 80%, and a sharp fundamental absorption edge with red-shifting was observed in the visible region. The optical band gap decreased from 3.95 eV to 3.80 eV when the AZO film thickness increased from 100 nm to 500 nm.