碳纳米管/聚合物基柔性电磁干扰屏蔽复合材料研究进展

当今,柔性可穿戴电子设备、航空航天等领域的快速发展对柔性、轻质电磁干扰(electromagnetic interference,EMI)屏蔽材料的需求不断增加,碳纳米管/聚合物基复合材料因具有柔性好、质量轻、导电性和机械稳定性优异、EMI屏蔽效能可调等优点而备受关注。本文介绍了电磁屏蔽机理,对碳纳米管的分散方法和碳纳米管/聚合物基柔性EMI屏蔽复合材料的制备方法进行了对比总结,综述了碳纳米管/聚合物基柔性EMI屏蔽复合材料的研究进展。最后,提出了碳纳米管/聚合物基柔性EMI屏蔽复合材料亟待解决的关键科学问题,并对其未来发展趋势进行了展望。     

木质素先进材料的研究进展

综述了木质素改善合成高分子材料的性能和制备光电材料、阻燃材料、电磁屏蔽材料等方面的研究进展。加强木质素结构和性能的基础研究,解决木质素反应活性偏低以及与基体相容性差的问题,将木质素的耐辐射、可生物降解、阻燃、电磁屏蔽等特异性能引入到传统合成高分子材料中,制备性能优异、功能多样的先进高分子材料,是木质素高值化利用的一个重要方向。     

含硼氮配位键的高分子电子受体材料

全高分子太阳能电池用高分子电子给体材料和高分子电子受体材料的共混物作为光电活性层,是光伏技术的重要发展方向之一.鉴于高分子受体材料的种类和数量都很少,开发新型高分子受体材料是发展全高分子太阳能电池的关键.有别于采用酰亚胺结构设计高分子受体材料的传统思路,我们从硼氮配位键降低π-共轭体系最低未占分子轨道(LUMO)能级的基本原理出发,在国际上率先提出了用硼氮配位键设计高分子受体材料的策略.本文旨在总结我们在含硼氮配位键的高分子受体材料方向的研究进展.首先阐明了硼氮配位键降低LUMO能级的原理,揭示出硼氮配位键在重复单元和高分子中的3个作用,然后介绍了硼氮配位键高分子受体材料的2种分子设计方法,阐明了硼氮配位键高分子受体材料在LUMO轨道和LUMO能级调控方面的特征,介绍了硼氮配位键高分子受体材料的吸收光谱调控、能级结构调控和电子迁移率调控,实现了全高分子太阳能电池的器件效率从2015年的0.14%到目前的6%的转变.最后,展望了硼氮配位键高分子受体材料在高性能全高分子太阳能电池方面的前景和重点发展方向.     

高分子化学灌浆材料在我国的发展和应用

高分子化学灌浆材料,是在水泥、粘土、沥青等传统灌浆材料的基础上发展起来的一种以有机高分子化合物为主的新型灌浆材料。随着现代大工业的发展,各种巨型工程(特别是地下工程和高层建筑)飞速兴建,对化学灌浆材料提出越来越高的要求;同时,由于高分子科学理论和高分子工业的发展,为各种新型灌浆材料的研制开拓了广阔的前景,特别是有机高分子材料,由于它结构的多样性和性能的可变性,为多种新材料的研制创造了有利条件。     

新型四喹啉取代的螺芴衍生物的合成与性质

近年来电致发光材料的研究非常迅猛,但是作为电子传输材料除了噁二唑及衍生物之外,还是比较缺乏.喹啉是缺电子环,其高分子衍生物可以作为发光材料和电子传输材料应用于OLEDs中,但基于喹啉发光小分子却研究较少.     

聚(3,4-乙烯二氧噻吩)在电磁屏蔽领域的应用

随着现代电子信息技术的迅猛发展,电磁干扰问题日益严重,发展综合性能优异的电磁屏蔽材料具有重要意义.聚(3,4-乙烯二氧噻吩)(poly(3,4-ethylenedioxythiophene),PEDOT)具有分子结构简单、能隙小、电导率高等特点,为高性能电磁屏蔽材料的实现提供了新途径.同时,随着对材料电磁屏蔽性能研究的深入以及制备技术的进步,将PEDOT与其他材料复合,通过合理的组分选择与结构设计,可以协同发挥各组分间电磁匹配特性,从而使PEDOT更好地满足柔性显示、智能可穿戴设备、高频器件、高精密电子设备等应用领域对电磁屏蔽材料"厚度薄、密度低、屏蔽强、屏蔽带宽宽"的具体要求.近年来,较多的研究致力于此并取得重要的成果.本文对以PEDOT为功能组分的电磁屏蔽材料的最新研究进展进行了综述,将近年来PEDOT及其与不同功能组分复合(包括导电组分、磁性组分及无电磁特性组分)构筑的电磁屏蔽材料体系的制备及电磁性能进行归纳总结,重点讨论电磁组分、微观结构与电磁屏蔽特性的联系,及其电磁屏蔽机理与性能优化方式,并对PEDOT在电磁屏蔽研究领域的机遇与挑战进行了展望.     

高分子基电极材料在电化学储能中的应用进展

高效电化学活性材料是实现高性能电化学储能设备的关键核心之一.如何在原子层次对电极材料微观结构进行精密调控,并发展有效合成策略和方法实现的结构控制合成,以提升器件电化学性能是备受关注的科学问题和基础研究的前沿.高分子材料理化结构丰富、官能团种类可调,已成为现代工业发展中的重要基石.特别是刚性芳杂环高分子基材料由于含有芳杂环结构,利于高温聚合且残炭率高,在碳化后具有良好的元素、形貌继承性,因此刚性芳杂环高分子基材料近年来在电化学储能领域也得到了广泛应用.系统总结了刚性芳杂环高分子基电极材料在超级电容器、钠离子电池、锂硫电池等电化学储能器件中的应用.并特别介绍了本课题组通过本征掺杂方式创制出的系列元素、形貌可控的高分子基电极材料.最后,总结并展望了高分子基材料在能源领域中未来的研究方向.     

空间电荷转移高分子荧光材料

空间电荷转移高分子荧光材料是利用非共轭高分子骨架实现电子给体与电子受体的空间π-堆积,继而通过空间电荷转移发光的高分子荧光材料,无论是在化学结构还是在发光本质方面均有别于基于共轭高分子骨架和化学键电荷转移发光的经典高分子荧光材料,已经成为发展高分子荧光材料的新途径.本文围绕空间电荷转移效应的实现、发光特性调控及其器件应用三个方面,总结空间电荷转移高分子荧光材料与器件方面的研究进展,重点讨论给体与受体空间相互作用的调控途径,包括给体与受体的强度与平面性、作用距离与排列方式以及多重给/受体结构对空间电荷转移效应、热活化延迟荧光效应以及电致发光性能的影响规律.同时分析了空间电荷转移高分子荧光材料未来发展面临的机遇和挑战.     

高分子基金属复合材料的前沿应用

高分子基金属复合材料作为一种具有独特物理属性的功能材料,兼具金属的高导电导热性以及加工便利性。近年来,高分子基金属复合材料成为科技前沿热点。复合材料不仅在芯片堆叠、集成电路和系统集成等高精度封装中实现技术突破,而且为医疗传感装置、柔性显示屏和软体机器人的开发提供了新思路。本文系统介绍了高分子基金属复合材料,从工作性能、应用概况及市场分析等方面总结其在电子封装、柔性显示、医疗传感和电磁屏蔽领域的的研究现状。     

防辐射材料的研究进展

综述了X射线、γ射线和中子辐射屏蔽材料的研究现状,其中在稀土高分子防辐射材料的设计与制备方面有所侧重,并且对纳米技术的应用、屏蔽材料的优化设计等进行了简单分析、介绍,指出了未来防辐射材料研究的可能的几个主要发展方向:纳米技术及稀土材料在防辐射材料方面的应用及研究;综合辐射屏蔽材料的设计与制备,使材料兼具质轻、无毒、体积小、屏蔽范围广、屏蔽性能持久等性能;屏蔽材料物理性能优化,以提升材料拉伸强度、硬度、耐腐蚀性等;屏蔽材料的优化设计方法、遗传算法、MCNP程序、梯度材料设计等的研究与应用;以上几个方向的交叉研究与应用。     

EMI shielding and dynamic mechanical analysis of graphene oxide-carbon nanotube-acrylonitrile butadiene styrene hybrid composites

Carbon nanomaterials such as carbon nanotubes (CNTs), graphene and their hybrid have been studied extensively. Despite having excellent properties of CNTs and graphene have not yet been fully realized in the polymer composites. During fabrication agglomeration of CNTs and restacking of graphene is a serious concern that results in the degradation of properties of nanomaterials into the final composites. To improve the dispersion of CNTs and restacking graphene, in the present research work, we focused on the hybridization of graphene oxide and CNTs. Multiwalled carbon nanotubes (MWCNTs), functionalized carbon nanotubes (FCNTs), and graphene oxide-carbon nanotubes (GCNTs) reinforced acrylonitrile butadiene styrene (ABS) composites were prepared separately by vacuum filtration followed by hot compression molding. Further, dynamic mechanical analysis (DMA), and electromagnetic interference (EMI) shielding properties of ABS composites reinforced carbon nanofillers were investigated. The dynamic mechanical properties of polymers strongly depend on the adhesion of fillers and polymer, entanglement density of polymer chains in the presence of carbon fillers. The dynamic mechanical characteristics such as storage, loss modulus, and damping factor of prepared composites were significantly affected by the incorporation of MWCNTs, FCNTs, and GCNTs. Maximum EMI shielding effectiveness of −49.6 dB was achieved for GCNT-ABS composites which were highest compared to MWCNTs-ABS composites (−38.6 dB) and FCNTs-ABS composites (−36.7 dB) in the Ku band (12.4–18 GHz). These results depict the great potential of GCNTs-ABS composites to be used in various applications of efficient heat dissipative EMI shielding materials for electronic devices.     

Current trends in spinel based modified polymer composite materials for electromagnetic shielding

The present article deals with current trends in spinel based modified polymer composite materials for applications in the field of electromagnetic shielding. The interaction between the various spinel based materials and polymers is an emerging field of studies among various researchers. The thermal stability, electrical conductivity, the bonding between the metal ferrites and the polymer plays an important role in the interaction of electromagnetic radiation. These properties also effect the mechanism of the EM waves for the shielding applications. Considering these all properties, polyaniline appears to be an suitable polymer for electromagnetic shielding applications. Polyaniline composites not only reinforced the properties of spinel materials but also enhanced the dielectric properties of the composite material. When carbon based materials such as graphene, graphene oxide and CNT was added along with spinel material in polyaniline based composite, they accelerate the electrical properties and enhances the shielding applications. In this paper the various synthesis methods, fabrication methods of polyaniline, and the properties of polyaniline based composites have been discussed. In addition, the various salient features and futuristic challenges of polyaniline based composite materials for EMI shielding applications were attempted to make a well equipped material for radar absorption.     

Electromagnetic Interference Shielding Polymers and Nanocomposites - A Review

Intrinsically conducting polymers (ICP) and conductive fillers incorporated conductive polymer-based composites (CPC) greatly facilitate the research in electromagnetic interference (EMI) shielding because they not only provide excellent EMI shielding but also have advantages of electromagnetic wave absorption rather than reflection. In this review, the latest developments in ICP and CPC based EMI shielding materials are highlighted. In particular, existing methods for adjusting the morphological structure, electric and magnetic properties of EMI shielding materials are discussed along with the future opportunities and challenges in developing ICP and CPC for EMI shielding applications.     

Biopolymer-Based Aerogels for Electromagnetic Wave Shielding and Absorbing

The rapid development of communication technology and electronic industry has brought unprecedented serious electromagnetic interference (EMI) and electromagnetic wave (EMW) pollution. Although EMI shields and EMW absorbers based on metal or magnetic materials were used to solve these problems, they have long been criticized for their high price, high density and easy corrosion. In order to achieve low density and efficient dissipation of electromagnetic energy, aerogels stand out among manifold materials. However, constructing aerogels with good EMI shielding or EMW absorption performance and acceptable mechanical properties is not an easy task. Burgeoning biopolymers, such as cellulose, lignin, chitin/chitosan and alginate, breathe new life into aerogels for high-efficiency EMW shielding and absorbing. Here, we reviewed the contributions of biopolymers in the fields of aerogels for EMW shielding and absorbing. At the same time, some challenges and outlook were also pointed out, aiming to promote the advance of aerogel-based EMI shields and EMW absorbers as well as the rational utilization of biopolymers.     

Progress in the Foaming of Polymer-based Electromagnetic Interference Shielding Composites by Supercritical CO2

As a critical action plan formulated for peaking carbon dioxide emissions, polymeric electromagnetic interference (EMI) shielding materials based on CO₂ foaming technology have recently been attracting widespread attention in both research and industry, attributable to their efficient use of CO₂, high specific strength, corrosion resistance and low-cost characteristics. In the past decade, the emergence of novel design concepts and preparation techniques for CO₂ foaming technology has led to the development of new high-performance EMI shielding materials in this field. This review summarizes the research progress made to date on the fabrication of EMI shielding composite foams by supercritical carbon dioxide (scCO₂) foaming. We also explore the structure-activity relationships between the component/distribution and EMI shielding properties. Additionally, the application prospects and development challenges of new EMI shielding composite foams are described.     

Improving Elasticity of Conductive Silicone Rubber by Hollow Carbon Black

Carbon black-based conductive rubber composites have important impacts on electromagnetic interference(EMI) shielding applications. However, an excessive amount of carbon black in the recipes of these conductive rubbers has caused their weak elasticity. Herein, hollow carbon black(HCB) particles were used to tune the elasticity of conductive rubber composites. Unique hollow morphology produced a better compression recovery of HCB than other solid carbon black, such as acetylene black. When the coupling agent was bonded to HCB, their conductive silicone rubber composites were featured by high stretching resilience, a fast compression recovery and excellent conductivity to satisfy the electromagnetic interference shielding requirements. Importantly, the rubber composites with coupling HCB had extremely low variations of mechanical property, conductivity and EMI shielding effectiveness after thermal accelerated aging tests. It is therefore revealed that the elasticity of HCB and its interfacial chemical coupling with rubber chains both play crucial roles in adjusting the elasticity of conductive rubber to sever long-term EMI protection.     

Preparation of nylon MXD6/EG/CNTs ternary composites with excellent thermal conductivity and electromagnetic interference shielding effectiveness

In this article,hybrid fillers with different dimensions,namely,2-dimensional (2-D) expanded graphite (EG) and 1-dimensional (1-D) multi-walled carbon nanotubes (CNTs),were added to aromatic nylon MXD6 matrix via melt-blending,to enhance its thermal and electrical conductivity as well as electromagnetic interference shielding effectiveness (EMI SE).For ternary composites of MXD6/EG/CNTs,the electrical conductivity reaches up nine orders of magnitude higher compared to that of the neat MXD6 sample,which tumed the polymer-based composites from an insulator to a conductor,and the thermal conductivity has been enhanced by 477％ compared with that of neat MXD6 sample.Meanwhile,the EMI SE of ternary composite reaches ～50 dB at the overall filler loading of only 18 wt％.This work can provide guidance for the preparation of polymer composites with excellent thermal and electrical conductivity via using hybrid filler.     

Towards efficient electromagnetic interference shielding performance for polyethylene composites by structuring segregated carbon black/graphite networks

An electromagnetic interference (EMI) shielding composite based on ultrahigh molecular weight polyethylene (UHMWPE) loaded with economical graphite-carbon black (CB) hybrid fillers was prepared via a green and facile methodology, i.e., high-speed mechanical mixing combined with hot compression thus avoiding the assistance of the intensive ultrasound dispersion in volatile organic solvents. In this composite, the graphite-CB hybrid fillers were selectively distributed in the interfacial regions of UHMWPE domains resulting a typical segregated structure. Thanks to the specific morphology of segregated conductive networks along with the synergetic effect of large-sized graphite flakes and small-sized CB nanoparticles, a low filler loading of 7.7 vol% (15 wt%) yielded the graphite-CB/UHMWPE composites with a satisfactory electrical conductivity of 33.9 S/m and a superior shielding effectiveness of 40.2 dB, manifesting the comparable value of the pricey large-aspect-ratio carbon nanofillers (e.g., carbon nanotubes and graphene nanosheets) based polymer composites. More interestingly, with the addition of 15 wt% graphite-CB (1/3, W/W) hybrid fillers, the tensile strength and elongation at break of the composite reached 25.3 MPa and 126%, respectively; with a remarkable increase of 58.1% and 2420% over the conventional segregated graphite/UHMWPE composites. The mechanical reinforcement could be attributed to the favor of the small-sized CB particles in the polymer molecular diffusion between UHMWPE domains which in turn provided a stronger interfacial adhesion. This work provides a facile, green and affordable strategy to obtain the polymer composites with high electrical conductivity, efficient EMI shielding, and balanced mechanical performance.     

Ku-band EMI shielding effectiveness and dielectric properties of Polyaniline-Y2O3 composites

Electromagnetic interference (EMI) shielding has become a phenomenon of great concern and there is growing demand towards the synthesis of materials with better EMI shielding effectiveness (EMI SE). This work highlights the preparation of Polyaniline-Yttrium Oxide (PANI-Y₂O₃) composites for EMI shielding applications in the frequency range from 12.4 to 18 GHz (Ku-band). The structure and morphology of the composites were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). EMI SE, microwave absorption and reflection, dielectric properties of the composites are discussed in detail. All the computations were based on microwave scattering parameters measured by transmission line waveguide technique. The observed results show absorption dominant EMI shielding in these composites with EMI SE of ?19 to ?20 dB, which mainly depends on the dielectric loss of the composites. Through the results of our observations, we propose these composites to be potential materials for microwave absorption and EMI shielding applications.     

Physical properties of CdS-poly (vinyl alcohol) nanoconducting composite synthesized by organosol techniques and novel application potential

A nanocomposite of poly (vinyl alcohol) (PVA) reinforced with various contents of CdS was synthesized by organosols reaction with particle size in the range of nanoscale. The influence of CdS content on the network structure of PVA matrix such as particle size distribution, gel fraction (GF), equilibrium water content (EWC), water absorption (WA), extent of filler reinforcement (γ), volume fraction of polymer (V_s) number of elastically effective chains (NEC), and X-ray diffraction (XRD) were investigated. The affine and phantom models for physical crosslinks were used to predict the nature of crosslinks. The thermal behavior of PVA-CdS composites has been studied by differential thermal analysis (DTA), Thermogravimetry (TG) and differential scanning calorimetry (DSC). The dc conductivity of the PVA system reinforced with CdS as a function of concentration and temperature has been presented. The PVA composite exhibits considerably high electronic conductivity which increases linearly with the increase of CdS content. The conduction mechanism in PVA-CdS composites is governing by hopping mechanism. The effects of CdS loading and temperature on the thermal conductivity (λ) and specific heats (C_p) were investigated. The antistatic properties and electromagnetic wave shielding effectiveness (EMI) of PVA-CdS composites has been also investigated. The optical properties such as absorbance and transient photo current under applied voltage of PVA-CdS composites were tested. The mechanical properties of PVA-CdS composites were investigated in details. It is proved that the PVA-CdS composites can be effectively used for linear thermistors, antistatic charge dissipation, EMI in the encapsulation of electronic devices, in woven texturing, optical switch and solar cell fabrication.