共查询到20条相似文献，搜索用时 15 毫秒
1.
Here, the creation of new supramolecular functional materials based on the reconstruction of three‐dimensional interconnecting self‐organized nanofiber networks by a surfactant is reported. The system under investigation is N‐lauroyl‐L ‐glutamic acid di‐n‐butylamide in propylene glycol. The architecture of networks is implemented in terms of surfactants, e.g. sorbitan monolaurate. The elastic performance of the soft functional material is either weakened or strengthened (up to 300% for the current system) by reconstructing the topology of a fiber network. A topology transition of gel fiber network from spherulite‐like to comb‐like to spherulite‐like is performed with the introduction of this surfactant. The Span 20 molecules are selectively adsorbed on the side surfaces of the crystalline fibers and promote the nucleation of side branches, giving rise to the transformation of the network architecture from spherulite‐like topology to comb‐like topology. At high surfactant concentrations, the occurrence of micelles may provide an increasing number of nucleation centers for spherulitic growth, leading to the reformation of spherulite‐like topology. An analysis on fiber network topology supports and verifies a perfect agreement between the topological behavior and the rheological behavior of the functional materials. The approach identified in this study opens up a completely new avenue in designing and producing self‐supporting supramolecular functional materials with designated macroscopic properties. 相似文献
2.
This article gives an overview of the current progress of a class of supramolecular soft materials consisting of fiber networks and the trapped liquid. After discussing the up‐to‐date knowledge on the types of fiber networks and the correlation to the rheological properties, the gelation mechanism turns out to be one of the key subjects for this review. In this concern, the following two aspects will be focused upon: the single fiber network formation and the multi‐domain fiber network formation of this type of material. Concerning the fiber network formation, taking place via nucleation, and the nucleation‐mediated growth and branching mechanism, the theoretical basis of crystallographic mismatch nucleation that governs fiber branching and formation of three‐dimensional fiber networks is presented. In connection to the multi‐domain fiber network formation, which is governed by the primary nucleation and the subsequent formation of single fiber networks from nucleation centers, the control of the primary nucleation rate will be considered. Based on the understanding on the the gelation mechanism, the engineering strategies of soft functional materials of this type will be systematically discussed. These include the control of the nucleation and branching‐controlled fiber network formation in terms of tuning the thermodynamic driving force of the gelling system and introducing suitable additives, as well as introducing ultrasound. Finally, a summary and the outlook of future research on the basis of the nucleation‐growth‐controlled fiber network formation are given. 相似文献
3.
4.
Da Wan Kim Sangyul Baik Hyeongho Min Sungwoo Chun Heon Joon Lee Ki Hyun Kim Jun Young Lee Changhyun Pang 《Advanced functional materials》2019,29(13)
Amphibian adhesion systems can enhance adhesion forces on wet or rough surfaces via hexagonal architectures, enabling omnidirectional peel resistance and drainage against wet and rough surfaces, often under flowing water. In addition, an octopus has versatile suction cups with convex cup structures located inside the suction chambers for strong adhesion in various dry and wet conditions. Highly air‐permeable, water‐drainable, and reusable skin patches with enhanced pulling adhesion and omnidirectional peel resistance, inspired by the microchannel network in the toe pads of tree frogs and convex cups in the suckers of octopi, are presented. By investigating various geometric parameters of microchannels on the adhesive surface, a simple model to maximize peeling strength via a time‐dependent zig‐zag profile and an arresting effect against crack propagation is first developed. Octopus‐like convex cups are employed on the top surfaces of the hexagonal structures to improve adhesion on skin in sweaty and even flowing water conditions. The amount of reduced graphene oxide nanoplatelets coated on the frog and octopus‐inspired hierarchical architectures is controlled to utilize the patches as flexible electrodes which can monitor electrocardiography signals without delamination from wet skin under motion. 相似文献
5.
6.
Michael D. Kempe Arrelaine A. Dameron Matthew O. Reese 《Progress in Photovoltaics: Research and Applications》2014,22(11):1159-1171
Many thin film photovoltaic (PV) technologies can be sensitive to corrosion induced by the presence of water vapor in the packaging materials. Typically impermeable front and backsheets are used in conjunction with an edge‐seal around the perimeter to prevent water vapor ingress. These edge‐seal materials are often made of a polyisobutylene resin filled with desiccant, which dramatically increases the time for moisture to reach sensitive module components. While edge‐seals can prevent moisture ingress, even the lowest diffusivity transparent encapsulant materials are insufficient for the lifetime of a module. To evaluate the performance of edge‐seal and encapsulant materials in a manner that simulates their function in a PV module, an optical method was devised where ingress is detected by reaction of a Ca film with water. Using this method, we have exposed test samples to heat and humidity allowing quantitative comparison of different edge‐seal and encapsulant materials. Next, we use measurements of polymer diffusivity and solubility to evaluate the ability to model this moisture ingress. Here, we find good agreement between these two methods highlighting the much greater ability of polyisobutylene materials to keep moisture out as compared with typical encapsulant materials used in the PV industry. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
7.
定子片精密冲模在设计和工艺制造上的不适当，以致造成阴阳模粘接结构发自下而上这重新确定应用环氧型结构胶，粘接工艺和修改冲模粘接结构，完好地修复冲模，冲制出的定子片性能达到技术要求。 相似文献
8.
《Progress in Photovoltaics: Research and Applications》2018,26(2):93-101
Often photovoltaic modules are constructed with materials that are sensitive to water. This is most often the case with thin film technologies, including perovskite cells, where the active layers are a few microns thick and can be sensitive to moisture, liquid water or both. When moisture or liquid water can ingress, a small amount of water can lead to corrosion and depending on the resulting reactions, a larger local detrimental effect is possible. To prevent moisture from contacting photovoltaic components, impermeable frontsheets and backsheets are used with a polyisobutylene (PIB)‐based edge seal material around the perimeter. Here, we evaluate the ability of a PIB‐based edge seal using a molecular sieve desiccant to keep moisture out for the expected module lifetime. Moisture ingress is evaluated using test coupons where the edge seal is placed between 2 pieces of glass, one of which has a metallic calcium film on it, and monitoring the moisture ingress distance as a function of time. We expose samples to different temperature and humidity conditions to create permeation models useful for extrapolation to field use. This extrapolation indicates that this PIB material is capable of keeping moisture out of a module for the desired lifetime. 相似文献
9.
Seth Allen Cazzell Bradley Duncan Richard Kingsborough Niels Holten-Andersen 《Advanced functional materials》2021,31(15):2009118
Rapid damping of interfaces experiencing vibrations is critical to the performance of many complex mechanical systems ranging from airplanes to human bodies. Current synthetic materials utilized in vibration damping are limited by either their damping frequency range, tunability, or environmental stability. Here, it is shown how single metal ion cross-linked hydrogels exhibit tunable damping across a large frequency range and multiple metal ion hydrogels exhibit broadband damping within a single material. Additionally, an enhanced resistance to freezing and dehydration is shown with the use of glycerol as a cosolvent. It is expected that material design principles presented here will help advance the development of programmable damping materials better able to meet the demands of sustained operation under broad environmental conditions. 相似文献
10.
对于小尺寸的空间遥感相机轻型探测器,为避免机械固定引入的装配应力对探测器感光面面形造成的影响,设计了一种轻型探测器粘接方法,计算胶层厚度减小粘接应力,保证粘接后的结构强度。首先,根据探测器组件工作环境选用合适的粘接剂为GHJ-01光学环氧胶和GD414硅橡胶,然后,通过无热粘接方程确定粘接胶层厚度为0.2 mm,并进行粘接面积计算,结合胶层参数制定了六种粘接方案;通过对探测器组件进行有限元仿真分析,计算了关键单元的变形情况,得到在温升工况下,探测器感光面面形变化低于0.001 2 mm的三种粘接方案;在经过随机振动和高低温热循环试验后,使用光学拼接仪和三坐标测量仪检测探测器拼接精度变化,对比试验结果得到最优粘接方案。最终检测结果表明,使用GD414硅橡胶粘接探测器底面和侧面,GHJ-01光学环氧胶顶部点胶的方案能够保证探测器组件在温升和力学振动条件下,保持面形精度优于0.000 7 mm,直线精度优于0.001 mm。对于小尺寸轻型探测器,最终优选的粘接方案能够满足粘接结构强度,符合探测器组件拼接精度要求。
相似文献11.
Chan Wang Yiran Hu Ying Liu Yizhu Shan Xuecheng Qu Jiangtao Xue Tianyiyi He Sijing Cheng Hong Zhou Weixin Liu Zi Hao Guo Wei Hua Zhuo Liu Zhou Li Chengkuo Lee 《Advanced functional materials》2023,33(38):2303696
The reliable function in vivo of self-powered implantable bioelectric devices (iBEDs) requires biocompatible, seamless, effective interactions with biological tissues. Herein, an implantable tissue-adhesive piezoelectric soft sensor (TPSS), in which the piezoelectric sensor converts biomechanical signals into electrical signals, and the adhesive hydrogel (AH) strengthens this conversion by seamlessly adhering the sensor on the wet and curvilinear surface, is proposed. The optimized AH exhibits strong adhesion to various organic or inorganic surfaces, including six commonly used engineering materials and three biological tissues. As a pressure sensor, TPSS proves good in vitro electrical performance with a high output of 8.3 V, long-term stability of over 6000 cycles, and high energy power density of 186.9 µW m−2. In a large animal experiment, TPSS seamlessly adheres to the right-side internal carotid artery of a Yorkshire pig to monitor blood pressure during a surgical operation. Compared to commercial sensors that work by inserting into tissues, TPSS does not cause any damage and can be peeled off after service. The integration of adhesive hydrogel and self-powered pressure sensors enables biocompatible, seamless, and more efficient interactions between the biological system and iBEDs, which also contributes to next-generation implantable bioelectronics with features of battery-free, intelligent, and accurate. 相似文献
12.
Frank M. L. van der Goes Gerard C. M. Meijer 《Analog Integrated Circuits and Signal Processing》1997,14(3):249-260
This paper presents a new universal transducer interface.This interface, which is read out by a microcontroller, servicesthe following sensor elements: capacitors, platinum resistors,thermistors, resistive bridges and potentiometers. The A/D conversionis based on a first-order oscillator. A combination of classicaland some new measurement techniques has been applied on a singlechip to obtain high accuracy, good long-term stability and areduction of the effects of interference and parasitic elements.The circuit has been fabricated in a 0.7 µm CMOSprocess. The main test results are: an accuracy of 10–15bits and a resolution up to 16 bits while the measurement timeis in the range 1–100ms. These results hold over the temperaturerange –20°C to 80°C. Calibrationof the electronic part is not required. The number of externalcomponents has been kept to a minimum. 相似文献
13.
Michael D. Kempe Dhananjay Panchagade Matthew O. Reese Arrelaine A. Dameron 《Progress in Photovoltaics: Research and Applications》2015,23(5):570-581
Photovoltaic devices are often sensitive to moisture and must be packaged in such a way as to limit moisture ingress for 25 years or more. Typically, this is accomplished through the use of impermeable front and backsheets (e.g., glass sheets or metal foils). However, this will still allow moisture ingress between the sheets from the edges. Attempts to hermetically seal with a glass frit or similarly welded bonds at the edge have had problems with costs and mechanical strength. Because of this, low diffusivity polyisobutylene materials filled with desiccant are typically used. Although it is well known that these materials will substantially delay moisture ingress, correlating that to outdoor exposure has been difficult. Here, we use moisture ingress measurements at different temperatures and relative humidities to find fit parameters for a moisture ingress model for an edge‐seal material. Then, using meteorological data, a finite element model is used to predict the moisture ingress profiles for hypothetical modules deployed in different climates and mounting conditions, assuming no change in properties of the edge‐seal as a function of aging. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
14.
要达到可靠的粘结效果，除了良好的粘结剂外，还需化工艺参数，如涂敷机器的参数设定、胶粘剂尺寸、固化曲线等。文中对贴片胶的造反贴片工艺以及ＳＭＴ中相关问题作了全面的介绍 。 相似文献
15.
16.
在变送器生产过程中，长期存在硅油渗漏造成变送器输出连续下降的问题。生产厂家分析渗漏的原因，选用了乐泰厌氧胶取代了以往用聚四氯四氟胶带密封和氩弧焊接，使变送器的粘接和密封工艺得到了改进和完善。 相似文献
17.
介绍了国内的3种机卡分离方案,并通过分析清华大学UTI标准的完善过程,总结机卡分离方案设计中存在的实际问题和解决方案.最后对未来的机卡分离技术进行了展望. 相似文献
18.
该设计为一种全自动智能新型风扇,通过热释电红外传感器,亦称为热红外传感器,是一种能检测人体发射的红外线的新型高灵敏度红外探测元件。它能以非接触形式检测出人体辐射的红外线能量的变化,并将其转换成电压信号输出。将输出的电压信号加以放大,便可驱动风扇电源开关控制系统,而且风扇具有灵敏的温度感测和显示功能,当它打开关闭风扇开关时,系统单片机作为控制平台对风扇转速进行控制。 相似文献
19.
有线电视网络的发展进入了数字时代,原先的模拟接收电视方式正在向新一代数字化接收过渡,由此新型交互式多媒体电视接收系统应运而生,数字电视机顶盒成为一个交互式数字电视系统中必不可少的重要组成部分,它在模拟电视和今天主流的数字电视二者间起连接的桥梁的作用。 相似文献
20.
Solder paste is the strategic material for the electronic card assembly process, based on the surface mounting technology.
The paste is a concentrated suspension (50% of volume) of metallic powder in an organic continuous phase and its screening
on the printed circuit board is the first operation of the assembly. The result of the screening depends strongly on the rheological
characteristics of the solder paste but, nevertheless the research activity on this material is so far very poor. In this
paper, an analytical procedure for the rheological characterization is given and the most important rheological parameters,
affecting the screening performance, are shown. 相似文献