Polyaniline/layered zirconium phosphate nanocomposites: secondary-like doped polyaniline obtained by the layer-by-layer technique

In the present work, nanocomposites of polyaniline (PANI) and layered alpha-Zr(HPO4)2 x H2O (alpha-ZrP) were prepared using two different approaches: (i) the in situ aniline polymerization in the presence of the layered inorganic material and (ii) the layer-by-layer (LBL) assembly using an aqueous solution of the polycation emeraldine salt (ES-PANI) and a dispersion of exfoliated negative slabs of alpha-ZrP. These materials were characterized spectroscopically using mainly resonance Raman scattering at four exciting radiations and electronic absorption in the UV-VIS-NIR region. Structural and textural characterizations were carried out using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The polymer obtained by the in situ aniline polymerization is located primarily in the external surface of the inorganic material although aniline monomers were intercalated between alpha-ZrP interlayer regions before oxidative polymerization. Through resonance Raman spectroscopy, it was observed that the formed polymer has semiquinone units (ES-PANI) and also azo bonds (-N=N-), showing that this method results in a polymer with a different structure from the usual "head-to-tail" ES-PANI. The LBL assembly of pre-formed ES-PANI and exfoliated alpha-ZrP particles produces homogeneous films with reproducible deposition from layer to layer, up to 20 bilayers. Resonance Raman (lambda0 = 632.8 nm) spectrum of PANI/ZrP LBL film shows an enhancement in the intensity of the polaronic band at 1333 cm(-1) (upsilonC-N*+) and the decrease of the band intensity at 1485 cm(-1) compared to bulk ES-PANI. Its UV-VIS-NIR spectrum presents an absorption tail in the NIR region assigned to delocalized free charge carrier. These spectroscopic features are characteristic of highly conductive secondary doped PANI suggesting that polymeric chains in PANI/ZrP LBL film have a more extended conformation than in bulk ES-PANI.     

Layer-by-layer self-assembly of polyimide precursor/layered double hydroxide ultrathin films

The layer-by-layer (LBL) self-assembly has been extensively used as a simple and effective method for the preparation of polyelectrolyte multilayer films. In this work, we utilized this unique method to prepare polyimide precursor/layered double hydroxide (LDH) ultrathin films. Well-crystallized Co-Al-CO₃ LDH and subsequent anion exchanged Co-Al-NO₃ LDH were prepared and characterized by scanning electron microscopy and X-ray diffraction (XRD). By vigorous shaking of the as-prepared Co-Al-NO₃ LDH, positively charged and exfoliated LDH nanosheets were obtained. Atomic force microscopy and XRD investigations indicated the delamination of LDH nanosheets. The precursor of polyimide, poly(amic acid) tertiary amine salt (PAS) was prepared by the polycondensation of dianhydride and diamine, and subsequent amine salt formation. By using the LBL method, heterogeneous ultrathin films of PAS and LDH were prepared. The formation of the ordered nanostructured assemblies was confirmed by the progressive enhancement of UV absorbance and the XRD results.     

Conductive and photovoltaic properties of multilayered ultrathin films designed by layer-by-layer assembly of titanium oxides

Titania-based ultrathin films were fabricated by layer-by-layer (LbL) assembly of titanium (IV) bis(ammonium lactato) dihydroxide (TALH) and polyelectrolytes. The thickness of the titania monolayer in the LbL films was 4-5 nm, which was consistent with the particle size of TALH in water. The conductivity and the electron mobility of the LbL films reached 10^− 8 S cm^− 1 and 10^− 5 cm² V^− 1 s^− 1, respectively. These results suggest that there exist percolation paths for the electron transport in the LbL film. Furthermore, it is demonstrated that photovoltaic properties of the LbL film can serve as an effective electron-transporting and accepting layer.     

溶胶凝胶法制备磷酸锆钠陶瓷材料

以Zr(NO3)4.5H2O、NH4H2PO4和NaNO3为原材料,采用溶胶凝胶法合成了磷酸锆钠(NaZr2(PO4)3)陶瓷粉体,采用TG-DTA,XRD和SEM测试方法对粉体性能进行了表征,研究了烧结温度和pH值等反应条件对粉体合成的影响.结果表明,要获纯的磷酸锆钠粉体,合成温度需控制在800～1 000℃之间,其中最合适合成温度为900℃左右.前驱体pH值对合成温度基本没有影响,但会影响产物微观形貌.当合成温度为900℃,pH值为9时可以制备出团聚较少、颗粒均匀、分散性较好且平均粒径为100nm的磷酸锆钠粉体.     

Multilayer films by spraying on spinning surface — Best of both worlds

The layer-by-layer buildup of poly(styrene sulfonate), poly(diallyldimethyl ammonium) and/or TiO₂-nanoparticles was carried out using an automated system which allowed spraying the polyion solutions on a spinning substrate. The different spraying and spinning arrangements were studied. The films were prepared by varying ionic strength, electrolyte species (NaBr and NaF) and spraying time. The results were compared to the films prepared by using the traditional dipping method. Depending on the electrolyte and the ionic strength the thickness of the films prepared with spraying on spinning substrate was thinner than or equal to the dipped films. It was found that addition of salt on spraying solutions is necessary in order to prepare thin films with a good quality. Spraying on spinning substrate generated evenly occupied smooth surfaces. The benefits of the automated method are attributed to the noticeably lower solution consumption and to the fact that the film deposition process could be accelerated by a factor of 100 comparing to the traditional dipping method.     

Enhanced hydrated properties of α-tricalcium phosphate bone cement mediated by loading magnesium substituted octacalcium phosphate

A novel Mg-containing α-tricalcium phosphate (α-TCP) bone cement with excellent wetting compressive strength and suitable setting time has been developed in this work. Mg-substituted octacalcium phosphate (Mg-OCP) crystals with the special morphology was prepared by homogeneous precipitation method, and used to modify the α-TCP bone cement. Mg²⁺ was successfully introduced into OCP structure, and the filaments/sheet-like morphologies of OCP were obtained by changing the Mg²⁺ concentration. As added in the α-TCP cement matrix, the effects of Mg-OCP on the wetting compressive strength, setting time and microstructure of the cement system were studied. The addition of Mg-OCP shortened the setting time of cement pastes with the minimum setting time of 15 min, and enhanced the wetting compressive strength of the hydrated cement products with the highest wetting compressive strength of 36.86 MPa. This work highlights the special morphologies of Mg-OCP induced by Mg²⁺ substitution, which made an effect on the hydration reaction of α-TCP cement; Furthermore, Mg-OCP was supposed to improve the condensation capacities and mechanical properties of α-TCP cement system as a novel cement admixture.     

Influence of bias voltage on the optical and structural properties of nc-Si:H films grown by layer-by-layer (LBL) deposition technique

The effects of applying a positive bias of 25 to 100 V on the optical, structural and photoluminescence (PL) properties of hydrogenated nanocrystalline silicon (nc-Si:H) films produced by layer-by-layer (LBL) deposition technique has been studied. Optical characterization of the films has been obtained from UV-VIS-NIR spectroscopy measurements. Structural characterization has been performed using X-ray diffraction, micro-Raman spectroscopy and field emission scanning electron microscope (FESEM). PL spectroscopy technique has been used to investigate the PL properties of the films. In general, the films formed shows a mixed phase of silicon (Si) nanocrystallites embedded within an amorphous phase of the Si matrix. The crystalline volume fraction and grain size of the Si nanocrystallites have been shown to be strongly dependent on the applied bias voltage. High applied bias voltage enhances the growth rate of the films but reduces the refractive index and the optical energy gap of the films. Higher crystalline volume fraction of the films prepared at low bias voltages exhibits room temperature PL at around 1.8 eV (700 nm).     

纳米金磁颗粒的组装法制备及其核酸分离性能

以丙烯酰胺为单体,采用原位聚合法制备了Fe3O4/聚丙烯酰胺纳米磁粒(Fe3O4/PAM);利用胺基与金的相互作用,借助自组装法在Fe3O4/PAM表面组装金胶体制备了草莓型纳米金磁颗粒(Fe3O4/PAM/Au);用TEM、VSM、UV-vis对其进行了表征,并考察了表面修饰核酸探针的金磁颗粒对核酸靶分子的分离能力。结果表明,Fe3O4/PAM/Au粒子的粒径为36～56nm,具有超顺磁性,饱和磁化强度为31.2emu/g,分散在磷酸盐缓冲液中的Fe3O4/PAM/Au完全磁分离的时间为6min。修饰核酸探针的Fe3O4/PAM/Au粒子可以借助核酸杂交作用分离核酸靶分子,分离能力为118pmol/mg。     

Preparation of nanosheet by exfoliation of layered iron phenyl phosphate under ultrasonic irradiation

Synthetic layered iron phenyl phosphate (Fe(OH)(C₆H₅PO₄H)_1.6(H₂PO₄)_0.4·5.1H₂O: FePP), which is composed of a multilayer alternating bilayer of phenyl groups of the phosphates and amorphous iron phosphate phase, was exfoliated in ethanol under ultrasonic irradiation. The exfoliation of FePP was recognized at 10-10,000 ppm of FePP concentration. No reaggregation and reprecipitation of the nanosheets took place for at least 6 months of standing at room temperature. The UV-vis measurements indicated that the nanosheet dispersing solution possessed a UV absorption property which would be due to the charge transfer transition of Fe-O. The FePP nanosheet-doped silica gel with UV absorption property could be prepared by sol-gel process. The Beer's plot and EDX elemental mapping analysis for Fe and P revealed that the nanosheets are homogeneously dispersed in the silica gels.     

Effects of organic chain length of layered zirconium phosphonate on the structure and properties of castor oil-based polyurethane nanocomposites

Three novel organic–inorganic hybrid molecules, layered zirconium phosphates or phosphonates, were synthesized. To study the effects of organic chain length of them on the structure and properties of polymer nanocomposites, the polyurethane/α-zirconium phosphate (PU/ZrP), polyurethane/zirconium 2-aminoethylphosphonate (PU/ZrAEP) and polyurethane/zirconium 2-(2-(2-(2-aminoethylamino)ethylamino)ethylamino) ethylphosphonate (PU/Zr(AE)₄P) nanocomposites were prepared, and characterized by Fourier Transform Infrared (FT-IR) spectroscopy, wide-angle X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and tensile testing. It was revealed that morphological, mechanical, and thermal properties of these nanocomposites were strongly dependent on the organic chain length of the layered zirconium phosphonates. The results showed that the fillers with longer chain length exhibited better dispersion in the PU matrix. As expected, the mechanical properties and water resistance were improved with the increasing of organic chain length of fillers, which attributed to better interfacial adhesion between fillers and PU matrix.     

水热法制备ITO薄膜的研究

以铟锡氯化物为原料,采用水热法在玻璃基片上制备了氧化铟锡(ITO)薄膜,并利用X射线衍射(XRD)、能谱分析(EDS)、扫描电子显微镜(SEM)等手段对薄膜的相结构、化学组成及形貌进行了表征,研究了水热温度和时间等条件对ITO薄膜光吸收特性的影响.结果表明,水热法制备的ITO薄膜呈体心立方多晶结构且均匀、致密.薄膜在可见光区透射比可达98.2%,具备低成本大规模制备ITO薄膜的潜力.     

Preparation and properties of ZnO thin films deposited by sol-gel technique

Zinc oxide (ZnO) thin films were deposited on (100) Si substrates by sol-gel technique. Zinc acetate was used as the precursor material. The effect of different annealing atmospheres and annealing temperatures on composition, structural and optical properties of ZnO thin films was investigated by using Fourier transform infrared spectroscopy, X-ray diffraction, atomic force microscopy and photoluminescence (PL), respectively. At an annealing temperature of 400°C in N₂ for 2 h, dried gel films were propitious to undergo structural relaxation and grow ZnO grains. ZnO thin film annealed at 400°C in N₂ for 2 h exhibited the optimal structure and PL property, and the grain size and the lattice constants of the film were calculated (41.6 nm, a = 3.253 ? and c = 5.210 ?). Moreover, a green emission around 495 nm was observed in the PL spectra owing to the oxygen vacancies located at the surface of ZnO grains. With increasing annealing temperature, both the amount of the grown ZnO and the specific surface area of the grains decrease, which jointly weaken the green emission. Translated from Journal of Lanzhou University (Natural Science), 2006, 42(1): 67–71 [译自: 兰州大学学报 (自然科学版)]     

低温水浴制备ZnO纳米晶薄膜的研究

首先在低温下制备了粒径小于10nm的ZnO纳米晶,然后采用旋口法制备了ZnO纳米晶薄膜,XRD分析ZnO晶相是纤锌矿结构;SEN与AFM表明,纳米晶薄膜在300℃退火后薄膜的厚度明显地减小到130nm（未退火200nm）,粒径明显增大,表面粗糙度减少到3．27nm（未退火4．89nm）;紫外-可见吸收和透射比光谱表明,随着退火温度的增加,吸收边发生了红移,吸收肩更明显,薄膜具有高的透射率（75—85％）,随着温度增加薄膜方阻增大,300℃以下退火方阻增加很小（小于8．5Ω／sq）,400℃以上退火方阻大幅增加（大于21．1n／sq）,假定存在最优退火温度点（300℃）。     

Characterization of chemically sprayed CdO films on borate and phosphate glass substrates produced by melt-quenching technique

The properties of substrates used to deposit thin films are an important parameter in thin film production. Instead of using a commercial substrate, in this work, borate and phosphate glasses have been obtained by classic melt-quenching technique to be used as substrates for CdO films. Also, a microscope glass substrate has been used to compare the coating properties by other glass substrates. All films have been produced by Ultrasonic Spray Pyrolysis technique. The substrate temperature has been selected as 275 ± 5 °C. Thicknesses and some optical parameters such as refractive index and extinction coefficient have been determined by spectroscopic ellipsometry. Absorbance and transmittance spectra have been taken by UV/VIS spectrophotometer. Four-probe method has been used to determine the electrical resistivity values of the films. XRD investigations have shown that type of the substrate dramatically affects the characteristics of CdO films. CdO film deposited on phosphate glass substrate has the best structural quality. Atomic Force Microscope has been used to investigate the surface properties and roughness values of the films.     

Sol-Gel法制备PLZT系铁电薄膜

介绍了Sol-Gel法，并对近年来Sol-Gel法制备PLZT系铁电薄膜材料的有关研究进行了分析和总结，详细介绍了Sol-Gel法制备PLZT系铁电薄膜材料的各种原料及工艺流程。     

静电自组装制备含苝衍生物的纳米层状复合膜

采用静电自组装方法制备了稳定的含苝衍生物纳米层状复合膜．用石英晶体微天平(QCM)对静电自组装过程进行了原位监控，发现组装次数与QCM频率变化呈线性关系，通过静电吸附得到的多层累积薄膜具有层状结构，X射线光电子能谱图上出现苝衍生物的特征峰表明组装的薄膜中含有苝衍生物．原子力显微镜表征结果表明，复合膜在一定程度上规整并且均匀的覆盖在电极表面，但存在分子团聚现象，将苝衍生物小分子溶解在聚电解质溶液中作混合浸渍液，提高了组装薄膜的稳定性．     

Influence of sintering temperatures on hardness and Young''s modulus of tricalcium phosphate bioceramic by nanoindentation technique

Nanoindentation experiments on tricalcium phosphate (TCP) bioceramic sintered at different temperatures were performed with a Berkovich indenter for determining hardness and elastic modulus from load and displacement data. The hardness and Young's modulus increased with the increase of sintering temperature up to 1300 °C, but the Young's modulus decreased with the further increase of sintering temperatures at 1400 and 1500 °C. X-ray diffraction (XRD) results showed that the transformation β→-TCP happened when the sintering temperature reached around 1400 °C, which contributed to the decreases of modulus at 1400 and 1500 °C. Scanning electron microscopy (SEM) results showed that the sintering effect was improved with the increase in sintering temperature.     

YSZ薄膜Sol-Gel法制备及其结构分析

本文应用Sol－Gel方法制备了YSZ薄膜,研究了工艺条件对薄膜微观结构的影响.实验发现：基片的选择和清洁、样品的凝胶化速度、热处理过程中的升降温速率等是影响薄膜开裂的几个主要因素．XRD和SEM分析结果表明：应用Sol－Gel方法制备的YSZ薄膜,热处理温度须达800℃以上才能完全排除其中的酸根、有机基因和碳元素,且形成完整的立方相结构．薄膜经500℃、1h热处理后,其表面呈明显的海绵状结构．随着烧结温度的升高,薄膜表面变得致密,气孔明显减少,至1050℃时,薄膜表面光滑、无裂纹、无针孔、圆球形的小颗粒均匀分布．薄膜与衬底的结合紧密,薄膜厚度均匀,膜厚约为1.0μm.