柠檬酸/PVA抗菌薄膜性能的研究

目的研究柠檬酸添加量对聚乙烯醇薄膜性能的影响。方法将柠檬酸颗粒溶解到质量分数为10%的PVA母液中,通过流延法制备柠檬酸/PVA抗菌薄膜。结果添加柠檬酸可降低薄膜吸水性和溶解性,随着柠檬酸质量分数的增加,透湿系数减小。观察扫描电镜表明,柠檬酸在聚乙烯醇中溶解均匀。以大肠杆菌和金黄色葡萄球菌为指标的抗菌性能测试表明,柠檬酸对大肠杆菌和金黄色葡萄球菌均有较强的抑制作用。结论柠檬酸的添加可降低PVA薄膜的吸水性、溶解性和水蒸气透过系数,并使薄膜具有抗菌性。     

微晶纤维素改性对聚乙烯醇薄膜性能的影响

目的研究不同添加量的微晶纤维素(MCC)对聚乙烯醇(PVA)薄膜性能的影响。方法通过共混溶液流延法制备得到MCC质量分数不同(0%,1%,2%,3%,4%)的PVA薄膜,测定分析MCC含量不同对PVA薄膜的颜色、光学性能、力学性能、阻隔性能、热稳定性和表面微观形态的影响。结果随着MCC含量的增加,PVA薄膜的透光率和断裂伸长率显著降低,雾度和抗拉强度显著增加,与纯PVA薄膜相比,MCC质量分数为4%的PVA薄膜的抗拉强度增加了64.8%,断裂伸长率降低了14.7%,水蒸气透过系数显著降低。当MCC质量分数从0%增加到3%时,薄膜的氧气透过系数由2.145×10~(-16) cm~3·cm/(cm~2·s·Pa)降低到1.393×10~(-16) cm~3·cm/(cm~2·s·Pa),但当MCC质量分数为4%时,薄膜的氧气透过系数略有增加。MCC的加入使得薄膜的热稳定性提高,初始分解温度略有升高,当MCC质量分数为4%时,薄膜表面和横截断面局部区域可以观察到少量的大颗粒出现团聚现象。结论 MCC的加入提高了PVA薄膜的力学性能、疏水性、阻隔性、热稳定性,控制好其加入量可以有效改善PVA薄膜的性能。     

AgNWs-TPU/PVDF柔性薄膜电容传感器的制备和性能

用醇还原法制备长径比约为800的银纳米线(AgNWs)并分散成网状结构,用溶液流延法使用聚偏氟乙烯(PVDF)和不同质量分数的聚氨酯(TPU)制备柔韧性PVDF/TPU复合薄膜,然后将AgNWs网固定在PVDF/TPU柔性薄膜的表面作为电容的极板制备出柔性薄膜电容式传感器。用扫描电子显微镜(SEM)、紫外-可见光谱和X射线衍射(XRD)等手段表征了AgNWs的结构,使用电子强力拉伸仪、方块电阻仪、三电极系统和LCR数字电桥检测了柔性薄膜电容式传感器的性能。结果表明：网状结构的AgNWs电容单侧极板上的方阻为15.635 mΩ/sq;TPU与PVDF质量比为2∶8的薄膜其断裂伸长率为91.2%,韧性最好,其比电容为375 μF/g;随着传感器弯曲角度的增大其输出电容值随之增大,输出电容值与弯曲角度在一定范围内呈线性关系,弯曲角度为180°时输出最大电容为436 μF。     

银纳米线透明导电薄膜的制备及其性能优化

随着柔性光电子技术的不断发展,传统的脆性氧化铟锡(ITO)透明导电薄膜材料已不能满足应用要求。银纳米线(Ag nanowires, AgNWs)透明导电薄膜因具有优异的导电性、透光性和机械性能,在柔性光电子器件中将具有广阔的应用前景。首先总结了AgNWs透明导电薄膜的成膜工艺方法,包括迈耶尔棒涂法、喷涂法、卷对卷涂布法、真空抽滤法和印刷法等。然后,从提高AgNWs透明导电薄膜的光电性能、稳定性、机械性能和与基材的附着力4个方面出发,介绍了各种性能优化处理工艺。最后,展望了AgNWs透明导电薄膜制备及性能优化的未来发展方向。     

氧化钒薄膜的制备技术及特性研究

采用直流反应磁控溅射法，通过精确控制反应溅射电压优化了氧化钒薄膜的制备工艺。对制备的氧化钒薄膜，利用四探针测试仪检测了薄膜的方阻和方阻温度系数，用X射线光电子能谱（XPS）仪和原子力显微镜（AFM）对薄膜的钒氧原子比和薄膜的微观形貌分别进行了分析和表征。实验结果表明，利用精确控制反应溅射电压法生长出的氧化钒薄膜的性能得到了进一步的提高。     

氧化钒薄膜的制备技术及特性研究

采用直流反应磁控溅射法,通过精确控制反应溅射电压优化了氧化钒薄膜的制备工艺.对制备的氧化钒薄膜,利用四探针测试仪检测了薄膜的方阻和方阻温度系数,用X射线光电子能谱(XPS)仪和原子力显微镜(AFM)对薄膜的钒氧原子比和薄膜的微观形貌分别进行了分析和表征.实验结果表明,利用精确控制反应溅射电压法生长出的氧化钒薄膜的性能得到了进一步的提高.     

还原氧化石墨烯基纳米银线透明导电薄膜研究进展

透明导电薄膜已广泛应用于印刷电子领域,传统的透明导电薄膜氧化铟锡（ITO）因其高脆性低柔韧性而不能满足高速发展的柔性电子行业;纳米银线（AgNWs）和石墨烯均具有良好光学性能、导电性能以及机械性能,使其能成为制备透明导电薄膜的理想材料。综述了近年来还原氧化石墨烯（rGO）基AgNWs透明导电薄膜的研究进展。介绍了柔性导电薄膜的关键参数及rGO/AgNWs透明导电薄膜的成膜工艺;归纳了影响rGO/AgNWs透明导电薄膜光电性能的主要因素和相关研究;阐述了rGO/AgNWs透明导电薄膜在印刷电子领域的应用现状,并展望了rGO/AgNWs透明导电薄膜的未来发展趋势。     

聚乙烯醇/纳米银薄膜的制备及其对黄骨鱼保鲜效果的研究

目的研究聚乙烯醇(PVA)/纳米银薄膜的抑菌性能,探索食品保鲜包装新方法。方法以PVA和水为基本原料,戊二醛为改性剂,用溶液流延法制备含有不同质量分数(1%,2%,3%)纳米银的PVA薄膜,分别表征其力学性能和耐水性能。将鱼肉用薄膜包裹,在4℃下贮藏,每隔3 d取样测定菌落数并进行感官分析。结果 PVA/纳米银薄膜对鱼肉有明显的抑菌作用,当纳米银添加质量分数为1%时,薄膜的拉伸强度为19.41 MPa,断裂伸长率为49%,力学性能良好;吸水率为32.2%,润湿角为55.1°,疏水性较好;与空白组相比,鱼肉货架期延长了4 d左右。结论质量分数为1%的纳米银能够增强薄膜的抑菌效果、有效维持鱼肉的感官品质,因此,在冷链运输中有很好的应用前景。     

均匀设计法优化聚乙烯醇/甲基纤维素薄膜吸湿性的研究

为优化薄膜的制备工艺,采用均匀设计法,对聚乙烯醇(PVA)/甲基纤维素(MC)薄膜吸湿性进行了研究。试验以PVA/MC的体积比、甘油含量、pH、戊二醛浓度为考察因素,以吸湿率为考察指标,建立了4因素7水平均匀设计试验,应用SPSS软件对数据进行了多元一次回归分析。结果表明:影响薄膜吸湿性的因素主次顺序为戊二醛浓度甘油含量体积比pH;当PVA与MC体积比为2:1,甘油含量为0.11mL/(100mL),pH为3.06,交联剂浓度为2.26×10-4 mol/L时,制得的薄膜吸湿率为2.68,抗张强度为42.17MPa,伸长率为48.2%,性能较优。     

PU/AgNWs/PDMS弹性导电复合材料的制备及性能研究

通过在预拉伸、经多巴胺改性处理的聚氨酯(PU)薄膜表面喷涂银纳米线(AgNWs),再用聚二甲硅氧烷(PDMS)固化处理得到了性能优良的PU/AgNWs/PDMS弹性导体。研究了PU/AgNWs/PDMS弹性导体在拉伸、弯曲形变下的电学性能。结果表明:经多巴胺改性处理的PU薄膜对AgNWs的吸附性能增强。所制备的PU/AgNWs/PDMS弹性导体在未形变下的电阻约为0.91Ω,1000次拉伸试验后导体在0%~20%拉伸形变范围内电阻变化很小(6%)。PU/AgNWs/PDMS弹性导体经过1000次的弯曲循环后电阻值未增加。     

A parametric study on synthesis of Ag nanowires with high aspect ratio

In this study, the effect of the experimental parameters of the polyol process on the aspect ratio of silver nanowires (AgNWs) was investigated. The one-factor-at-a-time method was adopted to analyze the effect of various parameters, such as the amount of reducing agent, seeds and the ratio of PVP/Ag, on the growth of AgNWs. The optimal parameters were determined to obtain a high aspect ratio of AgNWs. Synthesized AgNWs were analyzed by SEM, TEM, and XRD, and the four-point probe method was applied to measure the average aspect ratio, morphology, crystal direction, crystalline structure, and the electrically property of its sheet resistance. From the result of the morphology measurement, a high aspect ratio of 74.85 can be fabricated, where the average diameter and length were about ~55 and 4117 nm, respectively. Regarding electrical property, the sheet resistance of AgNWs with a high aspect ratio is about ~16.34 kΩ/sq with the film thickness of 142.1 nm. However, when the film thickness was increased to 1.123 µm, the resistance decreased to 3.012 Ω/sq.     

Transparent stretchable composite conductor based on silver nanowires with hybrid structure

Transparent stretchable conductors as the core parts of the next-generation devices have attracted a great deal of attentions and achieved progress in a variety of practical applications. However, the current challenge is still to fabricate highly transparent stretchable conductors which can maintain stable resistance even under severe deformation. Here, we propose for the first time a facile, low-cost and scalable method for fabricating silver nanowires (AgNWs)–polyurethane acrylate (PUA)–polyvinyl alcohol (PVA)–silver nanowires (AgNWs) composite films with PVA and AgNWs coated on AgNWs–PUA films. The films were stretched and released after spraying water. After the sprayed water dried, we could observe the resistance could only increase by 21 % under tensile strain up to 20 %. In addition, the composite remains perfectly stable after 500 bending cycles. Our strategy is also suitable for the fabrication of other functional composites with high stretchability.     

Highly conductive interwoven carbon nanotube and silver nanowire transparent electrodes

Abstract

Electrodes fabricated using commercially available silver nanowires (AgNWs) and single walled carbon nanotubes (SWCNTs) produced sheet resistances in the range 4–24 Ω □^?1 with specular transparencies up to 82 %. Increasing the aqueous dispersibility of SWCNTs decreased the bundle size present in the film resulting in improved SWCNT surface dispersion in the films without compromising transparency or sheet resistance. In addition to providing conduction pathways between the AgNW network, the SWCNTs also provide structural support, creating stable self-supporting films. Entanglement of the AgNWs and SWCNTs was demonstrated to occur in solution prior to deposition by monitoring the transverse plasmon resonance mode of the AgNWs during processing. The interwoven AgNW/SWCNT structures show potential for use in optoelectronic applications as transparent electrodes and as an ITO replacement.     

Transparent and flexible cellulose nanofibers/silver nanowires/acrylic resin composite electrode

In this study, we report a novel, eco-friendly and simple method to fabricate cellulose nanofibers (CNFs)/silver nanowires (AgNWs)/acrylic resin (AR) composite electrode. CNFs with average diameter of 15 nm were disintegrated only by one time-pass grinding. Aqueous dispersion of AgNWs was embedded onto the surface of CNFs film by simple vacuum filtration. The final composite electrode was obtained by impregnating CNFs/AgNWs film to AR with the assist of adhesive tape. This electrode with AgNWs density of 134 mg/m² showed low sheet resistance (4 Ω/sq), and high light transmittance (85%) which was 6% lower than that of neat AR. The coefficient of thermal expansion of the composite electrode was as low as 25.32 ppm K⁻¹. The tensile strength and Young’s modulus of CNFs/AgNWs/AR composite film were 35.71 MPa and 1.63 GPa, which were about 8 and 5.8 times larger than neat AR film, respectively.     

Electrical properties optimization of silver nanowires supported on polyethylene terephthalate

ABSTRACT

The aim of this study is the enhancement of the electrical properties of thin films obtained from silver nanowires (AgNWs) deposited on a flexible polyethylene terephthalate (PET) support. First, AgNWs were obtained by the “polyol” liquid phase synthesis method in the presence of chloride ions. After purification, the AgNWs were successively deposited on a flexible support of PET by doctor blade method. To improve the adhesion of the AgNWs coating to the substrate, thin films of polymethyl methacrylate (PMMA) were interposed between the layer of AgNWs and PET substrate. The properties of the thin films have been studied depending on the number of AgNWs layers and heat treatment procedure. Characterization of pure AgNWs as well as of AgNWs/PMMA/PET structures has been carried out by x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray analysis, transmission electron microscopy, UV–Vis spectroscopy, and scanning probe microscopy. The sheet resistance of the transparent conducting films was determined by four point probe measurement. Best results in terms of homogenous conductance across the film and optical transmittance have been obtained for samples prepared by deposition of four successive layers of AgNWs. Further heat treatment improved the conductivity of AgNWs on the PMMA/PET substrate. For these films, the sheet resistance decreased from 41.25 to 29.55 Ω/sq after 40 min of heat treatment in air at 150°C.     

Electrospray deposition of silver nanowire films for transparent electrodes

Silver nanowire (AgNWs) films were fabricated as transparent electrodes by electrostatic spray deposition (ESD) at atmospheric pressure and room temperature. The effects of solution concentration, spray flow rate, applied high voltage, and annealing temperature were characterized to obtain uniform films. AgNWs thin film was produced with ca. 20 Ω/[square] sheet resistance and 83% transparency in the visible range. Morphologies, optical and electrical properties, and stabilities of the films were investigated in this work. A maximum ratio of DC to optical conductivity of 288 was achieved in a 120 nm thick AgNW thin film. Chemical stability was evaluated in various solvents and we found that solvents had little effect on conductivity.     

Improved Optical Sintering Efficiency at the Contacts of Silver Nanowires Encapsulated by a Graphene Layer

Graphene/silver nanowire (AgNWs) stacked electrodes, i.e., graphene/AgNWs, are fabricated on a glass substrate by air‐spray coating of AgNWs followed by subsequent encapsulation via a wet transfer of single‐layer graphene (SLG) and multilayer graphene (MLG, reference specimen) sheets. Here, graphene is introduced to improve the optical sintering efficiency of a xenon flash lamp by controlling optical transparency and light absorbing yield in stacked graphene/AgNW electrodes, facilitating the fusion at contacts of AgNWs. Intense pulsed light (IPL) sintering induced ultrafast (<20 ms) welding of AgNW junctions encapsulated by graphene, resulting in approximately a four‐fold reduction in the sheet resistance of IPL‐treated graphene/AgNWs compared to that of IPL‐treated AgNWs. The role of graphene in IPL‐treated graphene/AgNWs is further investigated as a passivation layer against thermal oxidation and sulfurization. This work demonstrates that optical sintering is an efficient way to provide fast welding of Ag wire‐to‐wire junctions in stacked electrodes of graphene/AgNWs, leading to enhanced conductivity as well as superior long‐term stability under oxygen and sulfur atmospheres.     

Advanced Printing Transfer of Assembled Silver Nanowire Network into Elastomer for Constructing Stretchable Conductors

Excellent electrical performance of assemblies of 1D silver nanowires (AgNWs) has been demonstrated in the past years. Up to now, however, there are limited approaches to realize simultaneously deterministic assembly with dense arrangement of AgNWs and desired functional layouts. Herein, an assembly strategy from compressed air-modulated alignment of AgNWs to heterogeneous integration of stretchable sensing devices through printing transfer is proposed. In this process, a convective flow induced by compressed air brings the AgNWs to the air–droplet interface, where the AgNWs are assembled with excellent alignment and packing due to the surface flow, van der Waals, and capillary interactions. Compared with those random AgNWs networks, the oriented, densely packed AgNWs exhibit a lower and uniform electrical sheet resistance. To incorporate the AgNWs to an elastomer substrate, direct ink writing is employed to transfer the assembled AgNW network to the printed silicone elastomer with desirable patterns. Excellent electrical property is demonstrated including a wide electrical response range from 10% to 120% strain, and high electrical repeatability. An antibacterial property is confirmed, notifying additional benefit as wearable sensors. The printing transfer of preassembled AgNW networks to the printed elastomer patterns provides a facile strategy to construct stretchable electronic devices.     

Low haze transparent electrodes and highly conducting air dried films with ultra-long silver nanowires synthesized by one-step polyol method

Transparent electrodes made of silver nanowires （AgNWs） exhibit higher flexibility when compared to those made of tin doped indium oxide （ITO） and are expected to be applied in plastic electronics. However, these transparent electrodes composed of AgNWs show high haze because the wires cause strong light scattering in the visible range. Reduction of the wire diameter has been proposed as a way to weaken light scattering, although there have seldom been any studies focusing on the haze because of the difficulty involved in controlling the wire diameter. In this report, we show that the haze can be easily reduced by increasing the length of AgNWs with a large diameter. Ultra-long （u-long） AgNWs with lengths in the range of 20-100 μm and a maximum length of 230 μm have been successfully synthesized by adjusting the reaction temperature and the stirring speed of a one-step polyol process. Compared to typical AgNWs （with diameter and length of 70 nm and 10 μm, respectively） and ITO, a transparent electrode consisting of u-long AgNWs 91 nm in diameter demonstrated a low haze of 3.4%-1.6% and a low sheet resistance of 24-109 Ω/sq. at a transmittance of 94%-97%. Even when fabricated at room temperature without any post-treatment, the electrodes composed of u-long AgNWs achieved a sheet resistance of 19 Ω/sq, at a transmittance of 80%, which is six orders of magnitude lower than that of typical AgNWs.     

Flexible conductor fabrication via silver nanowire deposition on a polydopamine-modified pre-strained substrate

We fabricated a flexible conductor by depositing silver nanowires (AgNWs) on the surface of pre-strained polydopamine-modified polyurethane (PU) film. The polydopamine layer on the PU film created a highly hydrophilic surface that enhanced AgNWs adhesion to the PU film. When the pre-strained film was released, the PU film surfaces formed a uniformly buckled conductive layer. After embedding this substrate in polydimethylsiloxane (PDMS), a PU/AgNWs/PDMS flexible conductor was obtained. This flexible conductor can adapt to stretching (up to 20 % strain) and bending (3 mm bending radius) with slight changes in resistance, which was maintained at ~0.95 Ω after 1000 cycle tests. The resistance of the flexible conductor was 5.4 Ω under mechanical elongation of up to ~50 %, further demonstrating its obvious stretchable characteristics. Wavy AgNWs film-based stretchable conductors fabricated using a simple buckling approach could play an important role in the future development of flexible electronics.