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聚合物水化分子的微观结构研究 总被引:6,自引:0,他引:6
在聚合物水化分子微观结构研究中,必需使用冷冻升华方法制样才能基本保持样品的聚合物分子形态与原水化状态一致。风干制样方法会导致聚合物分子链卷缩,样品干缩成块,无法保留水化分子的原貌。放大倍数小于2000X的显微图像适于研究聚合物水化分子构成的骨架全貌;而放大倍数大于10000X后,更适于观察聚合物水化分子骨架的局部形态。聚合物分子在溶液中形成非均匀网络骨架,存在较粗的主干和较细的分枝。这种网络骨架既对水分子形成支撑,又吸附和包裹大量水分子产生形变阻力。大部分网络骨架不是由单个聚舍物分子构成,而是由聚合物分子聚集体形成。溶液中的盐份富集在聚合物分子的带电基团附近并形成浓度梯度分布。 相似文献
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本文通过扫描电镜对加入聚合物水泥水化试体各龄期水化产物形态的观察,研究了二种类型的聚合物乳液(不含羧基的、及含羧基的)对硅酸盐水泥水化硬化的影响。结果表明,聚醋酸乙烯酯乳液(PVAc)在水泥试体中能成膜,并吸附包裹水泥颗粒及其水化产物,但不影响纤维状水化物等结晶的形成;而聚丙烯酸聚酯乳液(PAE)则因含有羧基。要参与水泥的水化反应,并影响纤维状水化物等结晶的形成。二种聚合物乳液都能改善其强度等性能,但作用机理是不同的。 相似文献
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CS—Ⅰ型低温工作台 总被引:2,自引:2,他引:0
本文简单地介绍了CS—Ⅰ型电镜低温工作台的用途及技术规格。该系统可以使样品速冻,并在送样、制备及观察过程中保持真空和低温,最大程度地阻止样品形成冰晶,以便在电镜内观察到接近于自然状态的含水样品。CS—Ⅰ型低温工作台特别适宜于观察生物及其他的含水试样,可配于多种型号的扫描电镜。 相似文献
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由于干态聚合物电解质目前还不能满足聚合物锂离子电池的应用要求,人们致力于开发含液体增塑剂的聚合物电解质,包括凝胶型和微孔型两类体系。本文综述了含液聚合物电解质的最新进展,重点论述了各种新体系和新方法。 相似文献
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Yeon Sik Choi Jahyun Koo Young Joong Lee Geumbee Lee Raudel Avila Hanze Ying Jonathan Reeder Leonhard Hambitzer Kyungtaek Im Jungwon Kim Kyung‐Mi Lee Jianjun Cheng Yonggang Huang Seung‐Kyun Kang John A. Rogers 《Advanced functional materials》2020,30(31)
Bioresorbable electronic systems represent an emerging class of technology of interest due to their ability to dissolve, chemically degrade, disintegrate, and/or otherwise physically disappear harmlessly in biological environments, as the basis for temporary implants that avoid the need for secondary surgical extraction procedures. Polyanhydride‐based polymers can serve as hydrophobic encapsulation layers for such systems, as a subset of the broader field of transient electronics, where biodegradation eventually occurs by chain scission. Systematic experimental studies that involve immersion in phosphate‐buffered saline solution at various pH values and/or temperatures demonstrate that dissolution occurs through a surface erosion mechanism, with little swelling. The mechanical properties of this polymer are well suited for use in soft, flexible devices, where integration can occur through a mold‐based photopolymerization technique. Studies of the dependence of the polymer properties on monomer compositions and the rates of permeation on coating thicknesses reveal some of the underlying effects. Simple demonstrations illustrate the ability to sustain operation of underlying biodegradable electronic systems for durations between a few hours to a week during complete immersion in aqueous solutions that approximate physiological conditions. Systematic chemical, physical, and in vivo biological studies in animal models reveal no signs of toxicity or other adverse biological responses. 相似文献
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合成一种σ π共轭聚合物 poly(disilanylene 2 ,2′ bipyridine 5 ,5′ diyl)ruthenium (PDSBpy Ru) ,双光束耦合(2BC)、四波混频 (DFWM)及场致双折射实验等证明了该有机物的光导及光折变特性。由于铷化合物的金属与配位体间 (MLCT)电荷转移特性 ,使得该聚合物的光折变特性得以增强。实验测得双光束耦合增益系数为 30cm-1 ,四波混频实验测得光栅衍射率约为 1 0 %。 相似文献
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We present the optical properties and the temperature dependence of the resistivity of the pyrolyzed polyimide Pyraliin® which is electrically conducting. Our results indicate that the pyrolyzed material can be described as consisting of carbonized islands in an insulating matrix. 相似文献
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Narayanaswamy Kamatham Olzhas A. Ibraikulov Pablo Durand Jing Wang Olivier Boyron Benoît Heinrich Thomas Heiser Patrick Lévêque Nicolas Leclerc Stéphane Méry 《Advanced functional materials》2021,31(6):2007734
Herein reported is the impact of the functionalization of four different semiconducting polymer structures by a linear siloxane-terminated side-chains. The latter is tetrasiloxane (Si4) or trisiloxane (Si3) chains, substituted at their extremity to a pentylene linker. The polymer structure is based on 5,6-difluorobenzothiadiazole comonomer (PF2), a diketopyrrolopyrrole unit (PDPP-TT), a naphtalediimide unit (PNDI-T2), and a poly[bis(thiophen-2-yl)thieno[3,2,b]thiophene (PBTTT). The properties of these siloxane-functionalized polymers are scrutinized and compared with the ones of their alkyl-substituted polymer analogues. The impact of the alkyl-to-siloxane chain substitution clearly depends on the molecular section of the side chains. When a branched 2-octyldodecyl chain (C20) is replaced by a Si4 chain of same molecular section, the greatest impact is the strong increase of the π-stacking overlap of the polymer backbones. This effect leads to a significative enhancement of the charge mobility values of the polymers. As in-plane and out-of-plane mobility are increased simultaneously, this π-overlap enhancement effect happens to be preponderant over the polymer orientation variations. When a linear tetradecyl chain (C14) is replaced by a linear Si3 chain of twice larger molecular section, the polymer structure is profoundly affected. While PBTTT-C14 is crystalline and purely edge-on, PBTTT-Si3 is mesomorphic and shows a mixed face-on/edge-on orientation. 相似文献
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A 5 F-5 V prototype of solid state supercapacitor based on polymer electrolyte (PANI) and XSPEEK composing of six single cells stacked in series has been fabricated. The scale-up from a small single cell to a larger stack prototype of a solid-state electrochemical supercapacitor is discussed in this paper. The developed prototype showed a higher series resistance than estimated in our previous study on individual cell supercapacitor. The fabricated prototype achieved a specific capacitance of 480 F/g. The assembled capacitor has been characterized by cyclic voltammetry, impedance spectroscopy and galvanostatic charging/discharging. The performances of the electrodes have been compared with that of the single cell electrodes of area 4 cm2. 相似文献
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Conventional strain sensors based on metals and semiconductors are rigid and cannot measure soft and stretchable objects. Thus, new strain sensors based on polymer/nanomaterial composites are attracting more interest. Although much effort has been dedicated to achieve high values of both sensitivity and stretchability with linearity, this work endeavors to search and establish guidelines for the development of stretchable strain sensors, by critically reviewing conventional sensors and examining recent progress. It starts from introducing key parameters for conventional strain sensors; these parameters are further discussed for their potential impact on new polymer/nanomaterial strain sensors. The work concludes that there are no general benchmarks for conventional strain sensors utilized in industry. From the findings, the authors suggest that stretchable strain sensors should be custom designed and developed to meet particular measurement requirements, in comparison with a generic aim of yielding a sensor with high degrees of stretchability, sensitivity, and linearity. Challenges are discussed, including reliability, calibration to be used as proper gauges, and soft data acquisition systems. 相似文献