银纳米线电极微结构对柔性压力传感器灵敏度的影响

新型柔性压力传感器具有类似人体皮肤的可拉伸性以及对外力的感知特性,可被用于仿生电子皮肤及各种可穿戴电子设备,近年来引起了学术界和产业界的广泛关注。开发具有优异的传感灵敏度且制作工艺简单、节能、成本低廉的柔性压力传感器具有重要的科学与实际意义。本文以银纳米线(AgNWs)为电极材料,聚二甲基硅氧烷(PDMS)为柔性基底,分别采用PDMS相纸原位固化和抽滤转移固化2种方式制备银纳米线/PDMS复合电极,以聚酰亚胺薄膜(PI)为介电层,将两电极面对面层压封装,得到电容式柔性压力传感器。利用激光共聚焦显微镜和扫描电镜比较了2种制作工艺得到的电极微结构,并研究了上述电极微结构结构对传感器灵敏度的影响。研究结果表明,电极表面银纳米线的蓬松程度及粗糙度能显著影响器件灵敏度。电极表面银纳米线处于较密实状态、粗糙度为0.4μm的传感器灵敏度约为0.43kPa-1;当电极表面银纳米线较为蓬松且粗糙度增大为0.7μm时,传感器灵敏度增大到0.65kPa-1。本文制作的柔性压力传感器具有高灵敏度、低成本的特点,可用于诸如脉搏、心率,发声震动,细微压力变化监控等方面。     

铜纳米棒和纳米线水热还原制备的条件选择

用CuSO4·5H2O和NaOH为原料,一种六元脂肪族醇为还原剂,X射线衍射(XRD)和扫描电镜(SEM)为主要表征手段,研究了不同水热条件下铜的还原。结果表明,水热条件变化时,可以得到形貌各异的氧化亚铜和金属铜。其中,当n(OH-)∶n(Cu2+)∶n(醇)=4∶1∶1,,水热温度为180℃、反应时间为20h时,得到产物经XRD分析确定为金属铜,SEM照片显示,在产物中有纳米棒和纳米线形成,纳米棒的直径在100～500nm不等,长径比在50以上,而纳米线比纳米棒更细,蜿蜒曲折,柔韧性较好。     

Nanoenergetic Composites of CuO Nanorods,Nanowires, and Al‐Nanoparticles

This paper reports on the synthesis of the nanoenergetic composites containing CuO nanorods and nanowires, and Al‐nanoparticles. Nanorods and nanowires were synthesized using poly(ethylene glycol) templating method and combined with Al‐nanoparticles using ultrasonic mixing and self‐assembly methods. Poly(4‐vinylpyridine) was used for the self‐assembly of Al‐nanoparticles around the nanorods. At the optimized values of equivalence ratio, sonication time, and Al‐particle size, the combustion wave speed of 1650 m s⁻¹ was obtained for the nanorods‐based energetics. For the composite of nanowires and Al‐nanoparticles the speed was increased to 1900 m s⁻¹. The maximum combustion wave speed of 2400 m s⁻¹ was achieved for the self‐assembled composite, which is the highest known so far among the nanoenergetic materials. It is possible that in the self‐assembled composites, the interfacial contact between the oxidizer and fuel is higher and resistance to overall diffusional process is lower, thus enhancing the performance.     

Multilayer Actuator Composed of PZN–PZT and PZN–PZT/Ag Fabricated by Co-Extrusion Process

A multilayer ceramic actuator composed of piezoelectrically active Pb(Zn_1/3Nb_2/3)_0.2–Pb(Zr_0.5Ti_0.5)O_0.8 (PZN–PZT) layers and electrically conducting PZN–PZT/Ag layers was fabricated by the co-extrusion process. For the piezoelectric layers, PZN–PZT, which is sinterable at a low temperature (900°C), was used. For the conducting layers, a PZN–PZT/Ag composite, made by mixing silver particles with the PZN–PZT matrix, was employed. For the co-extrusion process, piezoelectric and conducting feedrods were made by mixing the PZN–PZT and PZN–PZT/Ag, respectively, with a thermoplastic polymer. The initial feedrods, which were composed of five 3 mm-thick PZN–PZT layers, two 1.5 mm-thick PZN–PZT layers, and six 1 mm-thick PZN–PZT/Ag layers, were co-extruded through a 24 mm × 2 mm reduction die at 105°C to produce continuous multilayered green sheets. The sheets were stacked, warm pressed, and sintered at 900°C for 4 h after binder burnout. The sintered multilayer actuator showed distinct layers without any reaction products or cracks at the interface. The thicknesses of the piezoelectric and conducting layers were about 200 and 70 μm, respectively. The displacement of the multilayer actuator, composed of 40 piezoelectric layers (with a total height of 10.8 mm), was about 10 μm at an applied voltage of 500 V.     

Synthesis and Characterization of Nanocomposite Powders Composed of Hydroxyapatite Nanoparticles and Wollastonite Nanowires

In the present study, the hydroxyapatite/wollastonite [Ca₁₀(PO₄)₆(OH)₂/CaSiO₃, HAp/CS] nanocomposite powders with different weight ratio were synthesized by a two-step chemical precipitation method under the aid of hydrothermal treatment. The products were characterized by X-ray diffraction, field-emission transmission electron microscopy, and X-ray fluorescence spectrometer. The results showed that the powders were composed of particle-like HAp and wire-like CS powders. The diameter of the HAp and CS were about 30–100 and 20–80 nm, respectively. The length of the CS nanowires was up to several micrometers.     

PVP导向ZnO纳米线、纳米棒的可控溶剂热合成及其生长机理研究

本文采用强碱性的溶剂热法,通过调控反应温度、时间、反应物投料比、特别是添加剂等影响因素,可控合成了两种不同形貌的一维ZnO纳米材料.利用透射电镜(TEM)和扫描电镜(SEM)研究了不同影响因素对ZnO产物形貌的影响.着重分析了添加剂聚乙烯吡咯烷酮(PVP)与纳米ZnO或其生长基元的络合作用,及其对纳米ZnO形貌的控制作用,并总结出强碱性溶剂热合成中反应温度、体系压强和pH值对ZnO产物形貌的作用机理.     

纳米Ag/TiO2复合材料的抗菌性能

采用Sol gel法制备掺杂不同质量分数银的纳米Ag/TiO2复合材料,研究了其对抗菌性能的影响。结果表明,银掺杂后的复合材料和应用其整理的纺织品不需紫外光照射就具有较强的抗菌性能,对大肠杆菌和金黄葡萄球菌的透明抑菌圈达到13～17mm。复合材料中银的掺杂能抑制粒径的长大,促进TiO2从锐钛型向金红石相的转移,但其质量分数对复合材料的抗菌性能影响不大。n(Ti)∶n(Ag)=20∶1时,复合材料的抗菌性能最佳,透明抑菌圈达到17mm。     

Synthesis of Ceramic Nanocomposite Powders with in situ Formation of Nanowires/Nanobelts

A significant challenge in synthesizing nanowire/nanobelt-reinforced ceramic nanocomposites is to uniformly disperse these reinforcements. Here, we report the synthesis of amorphous silicon carbonitride powders containing in situ- formed single-crystal Si₃N₄ nanowires and nanobelts via the catalyst-assisted pyrolysis of a polymeric precursor. The nanowires/nanobelts are uniformly dispersed within the powder matrix. The ratio of nanomaterials to powder can be controlled by tailoring the experimental conditions. The novel powders could be useful for fabricating nanowire/nanobelt-reinforced ceramic nanocomposites.     

Flexible Polymer/Clay Nanocomposite Films as Oxygen Supply Materials

PIB/MMT nanocomposite films containing UHP are fabricated and characterized for potential applications in wounded‐skin oxygen delivery and/or tooth cleaning. The UHP acts as a source of oxygen, whereas MMT creates a pathway for water molecules penetrating the film in order to generate a controlled release of H₂O₂ molecules. Most UHP particles are uniformly dispersed throughout the entire thickness of the films. DMA measurements indicate that the material retains most of its structural characteristics when exposed to water. SEM measurements show that no interface exists between individually spread multilayers. SAXS measurements indicate that the clay platelets are predominantly exfoliated and randomly oriented within the film. Controlled release of H₂O₂ is found over a period of ≈90–100 min.

     

Novel Insights into Inkjet Printed Silver Nanowires Flexible Transparent Conductive Films

Silver nanowire (AgNWs) inks for inkjet printing were prepared and the effects of the solvent system, wetting agent, AgNWs suspension on the viscosity, surface tension, contact angle between ink droplet and poly(ethylene) terephthalate (PET) surface, and pH value of AgNWs ink were discussed. Further, AgNWs flexible transparent conductive films were fabricated by using inkjet printing process on the PET substrate, and the effects of the number printing layer, heat treatment temperature, drop frequency, and number of nozzle on the microstructures and photoelectric properties of AgNWs films were investigated in detail. The experimental results demonstrated that the 14-layer AgNWs printed film heated at 60 °C and 70 °C had an average sheet resistance of 13 Ω∙sq⁻¹ and 23 Ω∙sq⁻¹ and average transparency of 81.9% and 83.1%, respectively, and displayed good photoelectric performance when the inkjet printing parameters were set to the voltage of 20 V, number of nozzles of 16, drop frequency of 7000 Hz, droplet spacing of 15 μm, PET substrate temperatures of 40 °C and nozzles of 35 °C during printing, and heat treatment at 60 °C for 20 min. The accumulation and overflow of AgNWs at the edges of the linear pattern were observed, which resulted in a decrease in printing accuracy. We successfully printed the heart-shaped pattern and then demonstrated that it could work well. This showed that the well-defined pattern with good photoelectric properties can be obtained by using an inkjet printing process with silver nanowires ink as inkjet material.     

Synthesis of Polyaniline Nanowires and Nanorods in the Presence of NaF under an Electric Field and Their Characterization

In this work, polyaniline nanowires and nanorods are synthesized through adjusting and controlling the concentration of D‐camphor‐10‐sulfonic acid (CSA) and NaF salt under the application of an electric field. The morphologies and structures of as‐synthesized polyaniline (PANI) are characterized through various methods, including transmission electron microscopy, UV–vis, Fouier transform infrared spectroscopy, and X‐ray diffraction. The results demonstrate that the introduction of an electric field can improve the crystallinity of PANI, and PANI nanowires/nanorods are fabricated through changing the amount of NaF or CSA in the presence of the electric field. Besides, the ¹H NMR experiments are executed to investigate the structures of final products.     

湿化学法制备氧化铜纳米棒

湿化学技术在工业上有着广泛的应用，而纳米材料也已成为科学研究的热点。本文报道了用湿化学技术制备氧化铜纲米棒。通过透射电镜(TEM)观察和X—射线粉末衍射(XRD)表征：所得氧化铜产品具有单斜晶形氧化铜纳米棒，其直径在20～90nm，长约500-1000nm长径比约为30。     

Ag/PAMAM树形分子纳米复合材料对PTFE膜性能的影响

以第4.0代端氨基聚酰胺-胺型树形分子(G4.0-NH2PAMAM)为模板制备Ag/PAMAM纳米复合材料(Ag·DENPs), 利用了Ag·DENPs与聚四氟乙烯(PTFE)膜表面的氢键作用,通过超声沉积的方法制备出了PTFE-Ag/PAMAM复合膜.通过研究沉积时间对Ag·DENPs在PTFE膜表面沉积量的影响,得到饱和沉积时间是60min,沉积量约为2.32mg.通过UV-vis光谱和SEM对其化学组成和微观形貌进行了表征.复合膜的水接触角为105.3°,较纯PTFE膜降低了23.6°,显著改善PTFE膜表面亲水性.复合膜对水和牛血清白蛋白的通量比纯PTFE膜低,但傅立叶变换衰减全反射红外光谱(FRR)为88.2%,比纯PTFE膜的35.4%高出了52.8%,且对大肠杆菌及金黄色葡萄球菌具有抑菌作用.表明Ag·DENPs的引入可以改善PTFE的抗污染性及抑菌性.     

以SDS为原料并作模板合成水溶纳米棒

通过引入Ca^2＋、NO3^-、Cl^-和十六烷基三甲基溴化胺,成功地合成了水溶性的Na2SO4纳米棒。XRD结果表明,实验制得的Na2SO4纳米棒纯度较高;SEM结果表明不同的外加物质对Na2SO4晶体的生长有显著影响。     

New Preparation Method for PZT Films Using Electrochemical Reduction

PZT perovskite films on stainless steel were prepared by electrochemical reduction in solutions containing TiO²⁺, ZrO²⁺, and Pb²⁺ ions. Heat treatment at temperatures higher than about 500°C was necessary for crystallization, because the as-deposited oxide films were amorphous. The deposited oxides consisted of a mixture of hydroxides and oxide produced by an increase of pH due to some electrochemical reduction reactions of NO₃⁻, H⁺, and H₂O on the electrode surface. The composition of the PZT films was easily controlled by the composition in solution during the electrolysis. The mechanism of the PZT precursor deposition is discussed.     

自牺牲模板法制备CdSe负载的CdS纳米线及其表征

以六方相CdS纳米线为前驱物，在不同浓度的Na2SeSO3溶液中，采用水热合成法制备了负载量可控的CdSe沉积的CdS纳米线复合材料。采用XRD、SEM、TEM、UV-Vis、PL和FTIR对该复合材料的物相、组成、形貌及光学性能进行了详细表征。结果表明，CdSe呈纤锌矿型六方相结构的纳米层形态沉积在CdS表面，其负载量受Na2SeSO3溶液浓度、反应温度和反应时间控制；与CdS纳米线相比，纳米复合材料的可见光吸收范围明显扩大，覆盖了可见光的大部分区域，而其中的CdS纳米线荧光因CdSe的存在出现淬灭现象，同样，也未观察到CdSe的荧光。文章详细讨论了相关的光学性质以及纳米复合物的反应机理。     

自牺牲模板法制备CdSe负载的CdS纳米线及其表征

以六方相CdS纳米线为前驱物,在不同浓度的Na2SeSO3水溶液中,采用水热合成法制备了负载量可控的CdSe沉积的CdS纳米线复合材料。采用XRD、SEM、TEM、UV-vis、PL和FTIR对该复合材料的物相、组成、形貌及光学性能进行了详细表征。结果表明,CdSe呈纤锌矿型六方相结构的纳米层形态沉积在CdS表面,其负载量受Na2SeSO3水溶液浓度、反应温度和反应时间控制;与CdS纳米线相比,纳米复合材料的可见光吸收范围明显扩大,覆盖了可见光的大部分区域,而其中的CdS纳米线荧光因CdSe的存在出现猝灭现象,同样,也未观察到CdSe的荧光。该文详细讨论了相关的光学性质以及纳米复合物的反应机理。     

Thermochemical Reactions Between PZT and Ag/Pd Powders: Relevance to Cofiring of Multilayer Actuators

Mixtures of Ag_{1− x} Pd _x ( x =0.2, 0.3) and doped PZT ceramic powders have been heat treated in air and the resulting phase content has been analyzed by X-ray diffraction and transmission electron microscopy. Beginning around 400°C, a phase similar to PbPdO₂ is formed on the surface of the Ag_{1− x} Pd _x particles and subsequently decomposes at temperatures <700°C. Consequently, the remaining Ag_{1− x} Pd _x powder becomes significantly silver-rich while the reaction progresses. After decomposition the Pd appears to realloy and the initial Ag_{1− x} Pd _x composition is recovered. We show that the reaction is all but eliminated in a nitrogen atmosphere. The occurrence of this reaction was also investigated in PZT multilayer actuators cofired with Ag_0.7Pd_0.3 electrodes. Transmission electron microscope analysis revealed the presence of distinct crystallites at the electrode–ceramic interface, most likely nucleated from a PbO liquid phase arising from the decomposition of PbPdO₂.