Wood-plastic composites based on HDPE and ionic liquid additives

The improvement of wood-plastic composites properties by additives and compatibilizers is a critical issue to produce value-added materials. High-density polyethylene-wood composites have been obtained through compression molding at 140 °C, using two types of additives, namely methyltrioctylammonium bis (trifluoromethylsulfonyl)imide and trihexyltetradecylphosphonium bis (2,4,4-trimethylpentyl) phosphinate room temperature ionic liquids. The ionic liquids improve the interfacial adhesion between the wood and the polymer phases, contributing to an increased stability of the material to water action and to an improved impact resistance and tensile strength in comparison with the reference. Also, the FTIR spectroscopy tests have proven a higher resistance of the ionic liquid-containing composites to accelerated photooxidation. Preliminary screening tests have also proven the antifungal character of the ionic liquids used in this study against brown rot (Postia placenta). This study opens new insights in the domain of polymeric composite materials, through documenting the possibility of blending new types of chemically distinct materials, difficult to be achieved by traditional functionalization/derivatization routes.     

Particulate composites based on ionic liquid-treated oil palm fiber and thermoplastic starch adhesive

Pretreatment of lignocellulosic materials is a highly essential and critical task for the manufacturing of engineered composite panels. Recently, ionic liquids (ILs) have emerged as a promising green solvent for lignocellulosic biomass disintegration. In this work, the impact of IL pretreatment on the flexural and thermal properties of the thermo-molded biocomposite panels made from oil palm biomass residue and thermoplastic starch biopolymer as binder was studied. Oil palm fiber was pretreated with IL [emim][dep] (1-ethyl-3-methylimidazolium diethyl phosphate) and IL [bmim][Cl] (1-butyl-3-methylimidazolium chloride) prior to mixing with plasticized starch. The compounded mixture was then hot-pressed into composite panels. To understand the effect of IL pretreatment, lignocellulosic characterization, morphology, and thermogravimetric analysis of the untreated and treated fibers were performed. It was found that thermal stability of the oil palm biomass and the biocomposites was improved after IL pretreatment due to partial removal of hemicellulose and lignin from raw fiber. Moreover, pretreated biocomposites exhibited superior strength and modulus as compared to that of untreated sample as evidenced from flexural testing. The study plainly demonstrates that IL-assisted pretreatment could be an extremely attractive and clean technology for the efficient use of agro-based industrial waste in biocomposite field.     

离子液体/金属-有机骨架复合材料制备方法、理论计算及应用研究进展

金属-有机骨架(MOF)是一种多孔、高比表面积的新型纳米材料.离子液体(IL)具有稳定性好、功能可设计的特点,将IL负载到MOF的孔中,实现离子液体和MOF材料的有效组合,开发新型功能化复合多孔材料,有利于充分发挥两种材料的优势.本文主要介绍IL/MOF复合材料合成方法、分子模拟及其应用的最新研究.总结目前IL/MOF...     

Review: carbon nanotube for microfluidic lab-on-a-chip application

Microfluidic lab-on-a-chip allows chemical and biochemical analysis to be conducted in a miniaturized system. Miniaturized analysis reduces the reagent consumption while decreasing the overall size of the device, but the small dose of the sample make detection more demanding and is more sensitive to adsorption of species on the surface. Integration of carbon nanotubes into microfludic devices is a promising approach. This review addresses recent advances in the application of carbon nanotubes for microfluidic lab-on-a-chip. The literature review shows that carbon nanotubes have been used to achieve superlubrifying microchannels, act as high density nanoporous membranes, electrical transducers mainly in flow sensors and biosensors, and mimics of living systems. In addition, extensive work has been carried out to investigate the tunable mechanical, chemical and electrical properties of carbon nanotubes in order to manipulate and analyse extremely small volumes of fluid effectively.     

基于MOFs的碳纳米管复合材料的制备和应用进展

碳纳米管(CNTs)作为纳米材料研究中的一个重要发现,自其诞生以来就成为碳材料领域的研究热点之一.金属有机框架(MOFs)凭借其独特的多孔结构,近年来在各领域的应用已经成为研究前沿之一.随着材料科学的不断发展,对具有不同功能特性材料的复合技术研究,已经成为解决材料应用领域中关键问题的主要方法.而碳纳米管和金属有机框架作为目前材料领域两类十分重要的纳米材料,通过复合技术将碳纳米管的高导电特性和金属有机框架材料的高比表面积、丰富孔道分布特性相结合是研究与应用的必然趋势.本文综述了近年来金属有机框架和碳纳米管的主要复合形式和制备方法,整理了复合材料在超级电容器、锂电池、催化、吸附等领域的最新研究进展,对两种材料性能的协同提升方面进行了讨论和总结,并指出CNTs与MOFs材料的复合以及CNTs的生长分布具有很高的随机性,对其实现进一步控制是未来的技术研究重点.     

Synthesis of ferrofluid based nanoarchitectured polypyrrole composites and its application for electromagnetic shielding

The monodispersion of magnetic nanoparticles in conducting polymer is the prerequisite to make a high quality composite for tunable electromagnetic interference (EMI) shielding. To meet this challenge, we have designed and synthesized ferrofluid based nanoarchitectured polypyrrole composites containing Fe₃O₄ (8–12 nm) via in situ oxidative polymerization. To tune the microwave signals, polypyrrole composites (PFF) with different monomer/ferrofluid weight ratios have been prepared and characterized in microwave frequency domain. A maximum shielding effectiveness value of SE_A(max) = 20.4 dB (∼99% attenuation) due to the absorption of microwave has been observed in the frequency range of 12.4–18 GHz and attenuation level varied with ferrofluid loading. The electrical conductivity of PFF composite is of the order of 10⁻² S cm⁻¹ order and having superparamagnetic nature with saturation magnetization (M_s) of 5.5 emu g⁻¹. The lightweight PFF composites with high attenuations can provide full control over the atomic structure and are favorable for the practical EMI shielding application for commercial electronic appliances.     

Metal matrix composites for industrial application

The present status of Metal Matrix Composite materials Research & Development (R&D) and industrial exploitation is summarised. Metal Matrix Composites (MMC) are defined and described and their value to the designer is discussed in the context of their technical strengths and weaknesses. The driving force for the present high level of investment in MMC R&D worldwide is discussed and the economic advantages of collaborative development initiatives are analysed. The present UK industrial collaborative MMC R&D programme is described and set in the context of the scope and objectives of major development programmes in the US, Japan and Europe.     

Optimization of microfluidic particle sorters based on dielectrophoresis

In this paper, improved dielectrophoretic particle sorters are introduced for application in microfluidics. The optimal shape of the electrodes is briefly discussed and two new sorter topologies are introduced. Based on the theoretical considerations, four sorter configurations are analyzed in detail. The devices are modeled by calculating the particle trajectories from a combination of finite-element simulations and analytical calculations. The four sorter configurations have been realized in chips based on silicon, glass, and SU8 technology. The simulations and the experimental results are in very good agreement and confirm that with the new sorter configurations, much higher performance can be realized (+200%) compared to the classical line electrodes found in literature.     

Automated microfluidic screening assay platform based on DropLab

This paper describes DropLab, an automated microfluidic platform for programming droplet-based reactions and screening in the nanoliter range. DropLab can meter liquids with picoliter-scale precision, mix multiple components sequentially to assemble composite droplets, and perform screening reactions and assays in linear or two-dimensional droplet array with extremely low sample and reagent consumptions. A novel droplet generation approach based on the droplet assembling strategy was developed to produce multicomponent droplets in the nanoliter to picoliter range with high controllability on the size and composition of each droplet. The DropLab system was built using a short capillary with a tapered tip, a syringe pump with picoliter precision, and an automated liquid presenting system. The tapered capillary was used for precise liquid metering and mixing, droplet assembling, and droplet array storage. Two different liquid presenting systems were developed based on the slotted-vial array design and multiwell plate design to automatically present various samples, reagents, and oil to the capillary. Using the tapered-tip capillary and the picoliter-scale precision syringe pump, the minimum unit of the droplet volume in the present system reached ~20 pL. Without the need of complex microchannel networks, various droplets with different size (20 pL-25 nL), composition, and sequence were automatically assembled, aiming to multiple screening targets by simply adjusting the types, volumes, and mixing ratios of aspirated liquids on demand. The utility of DropLab was demonstrated in enzyme inhibition assays, protein crystallization screening, and identification of trace reducible carbohydrates.     

基于气体基压电复合材料的线聚焦空耦超声传感器研制与应用

空气耦合式超声检测技术因具有非接触、无损伤等特点,被广泛应用于材料的非接触检测。本文从晶硅太阳能电池的实际检测需求出发,设计并制作了一种气体基线聚焦空气耦合（空耦）式超声传感器,与传统的聚合物基空气耦合（空耦）式超声传感器相比,气体基线聚焦空耦传感器利用了3D打印技术将聚合物基框架改进为镂空结构,进一步降低了压电复合材料的声阻抗。所研制的传感器中心频率约为150 kHz,聚焦半径为20 mm,孔径为28 mm。对传感器进行了激励接收性能测试,并采用空耦超声Lamb波检测技术,对含有裂纹缺陷的单晶硅太阳能电池片进行非接触式检测,通过分析接收信号的幅值信息并利用相关系数法,完成了对裂纹缺陷的检出和定位,实现了气体基线聚焦空耦传感器在缺陷检测中的应用。     

离子液体在电池中的研究与应用新进展

离子液体由于具有热稳定性好、不挥发、电导率高、不燃烧、电化学窗口宽等特点,其作为新一代功能电解质材料在电池体系中的应用成为当前研究的热点。综述了近几年国内外离子液体电化学性能的研究进展,并结合离子液体在电池领域的应用,叙述了离子液体作为电池新型绿色材料的最新研究进展。     

肿瘤微血管芯片的制备及其应用

肿瘤血管结构不同于正常组织血管,由内皮细胞松散地围成不完整的管道,呈高通透性.为建立体外简便、有效、低廉的肿瘤血管模型,本研究采用微加工技术,制作了肿瘤血管微流控芯片.芯片包括24 mm长50 μm宽40 μm深的微管道和一侧的微腔体以及两者之间的微缝.微管道中部设有膨胀区域以模拟肿瘤血管结构.在微管道内导入血管内皮细...     

离子聚合物金属复合材料电致动模型研究

离子聚合物金属复合材料（ionic polymer-metal composites,IPMC）是一种新型电致形变高分子材料,具有广阔应用前景。为了有效描述IPMC的形变规律,基于IPMC致动原理提出了一种电致动模型。建立了阶梯电压下IPMC膜内水合阳离子的力平衡方程,由水合阳离子的浓度分布及水分子的扩散计算得出水分子的浓度以及含水量分布,结合实验所确定的含水量和应变的关系从而确定IPMC沿厚度方向的应变分布。该计算方法适用于不同形状的IPMC致动器。以悬臂梁IPMC致动器为例,通过应变分布计算得到IPMC致动器在阶跃电压下的输出弯矩和相应的位移响应,模拟结果与实验结果的瞬时响应规律高度一致,证明该模型正确。该模型的建立为IPMC结构驱动一体化设计奠定了坚实的基础。     

Organic transistor based circuit as drive for planar microfluidic devices

Organic transistor based circuits are a promising candidate for acting as drivers for microfluidic devices handling discrete droplets. The ease of fabrication along with the ability to generate desired voltage levels for performing electrowetting based actuation of liquids make them an ideal match for discrete droplet based microfluidic systems. In this article, we report the implementation of an organic transistor based complementary metal-oxide semiconductor (CMOS) inverter used to actuate microliter quantities of droplets on a simple planar microfluidic device. We also present two approaches for fabricating an open-structured device for different applications. The inverter is fabricated using Pentacene and N, N′- bis (n-octyl) dicyanoperylene-3, 4:9, 10-bis (dicarboxyimide) (PDI-8CN₂) (Northwestern University). The inverter output is stable and repeatable and is used to actuate droplets over adjacent electrodes as well as in merging of discrete droplets.     

Laser-induced fluorescence detection system for microfluidic chips based on an orthogonal optical arrangement

In this work, a simple LIF detection system based on an orthogonal optical arrangement for microfluidic chips was developed. Highly sensitive detection was achieved by detecting the fluorescence light emitted in the microchannel through the sidewall of the chip to reduce scattered light interference from the laser source. A special crossed-channel configuration, with a 1.5-mm distance from the separation channel to the sidewall of the glass chip, was designed in order to facilitate collection of emitted fluorescence light through the sidewall. The significant difference in intensity distribution of scattered laser light on the chip plane observed in this study was fully exploited to optimize S/N ratio of detected signals by rejection of scattered light, both through systematic measurements and employing ray-tracing simulation. A fluorescence collection angle of 45 degrees in the chip plane gave the best result, with a scattered light intensity 1/38 of that obtained at an angle of 90 degrees. Sodium fluorescein and fluorescein isothiocyanate-labeled amino acids were used as model samples to demonstrate the performance of the LIF system. A detection limit (S/N = 3) of 1.1 pM fluorescein was obtained, which is comparable to that of optimized confocal LIF systems for chip-based capillary electrophoresis. Apart from the high detection power, the system also has the advantages of simple optical structure, compactness, and ease in building.     

Layered and interfacially blended polyelectrolyte multi-walled carbon nanotube composites for enhanced ionic conductivity

To enhance the ionic conductivity in solid phase polyelectrolyte systems for lithium ion battery applications demands effective control of the phase properties. Here, we report on a strategy involving a layer-by-layer methodology of two polyelectrolytes, poly(ethylene oxide) (PEO) and poly(acrylic) acid (PAA) and carboxylic acid functionalized multi-walled carbon nanotubes (MWNTs). Optimization of the assembly strategy revealed that undoped and lithium-ion doped stacking of four layers provides excellent film growth and improvement of the ionic conductivity of up to 10^− 5 S cm^− 1, which exceeds conventional assemblies of lithium-ion doped [PEO/PAA] by up to two orders of magnitude. Although ionic conductivity was most effectively enhanced for ultrathin films (< 100 nm), [PEO/PAA/PEO/(PAA + MWNT)] stacking still provides an ionic conductivity of > 10^− 6 S cm^− 1 for thick films (> 2 μm). The improvement of ionic conductivity was attributed to (i) interfacial phase mixing (blending) of the two polyelectrolytes, (ii) the MWNT contribution in the interfacial region, and (iii) the preferential adsorption of lithium-ions along the carbon nanotubes. This study involved a series of scanning probe methods including lateral force microscopy, and electrostatic force microscopy.     

Forming composites based on mineral fibers

The effect of aluminum sulfate additives on the structure of a composite material based on basalt fibers has been studied using electron microscopy and IR spectroscopy. The introduction of aluminum sulfate leads to the appearance of outgrowths fastening mineral fibers to each other at their intersection contacts. This is accompanied by the appearance of an absorption band in the IR spectra, which is attributed to hydrogen-bonded hydroxy groups. Estimates of the hydrogen bond lengths are obtained from an analysis of the IR absorption band shape.     

Conductive composites based on exfoliated graphite

Conductive composites of exfoliated graphite (EG) and coal-tar pitch have been prepared by mixing the components. The electrical properties of the composites have been studied, and the results have been interpreted in terms of the percolation theory. The threshold EG content for electrical conduction is determined to be ? 1.5 wt %, independent of the properties of the pitch and EG.     

基于灵敏度分析的复合材料组分参数识别方法

为了获取准确的复合材料细观模型,提出了一种复合材料组分参数识别方法。在细观单向碳纤维增强树脂基复合材料（CFRP）有限元模型基础上,构造静态位移场对复合材料组分弹性参数的灵敏度矩阵,以测量位移和有限元计算位移差的二范数为目标函数,针对待识别参数量纲差异较大的问题,利用相对灵敏度提高材料组分弹性参数识别的精度和效率。以纤维均匀分布的复合材料平面模型和纤维随机分布的复合材料实体模型为研究对象,验证所提出组分参数识别方法的有效性和准确性。此外,研究了测点数目及测量误差对识别结果的影响。结果表明：本文提出的复合材料组分参数识别方法在测点数目变化和测量误差影响下仍然稳定。     

Electrokinetically based approach for single-nucleotide polymorphism discrimination using a microfluidic device

In this work, we describe and implement an electrokinetic approach for single-nucleotide polymorphism (SNP) discrimination using a PDMS/glass-based microfluidic chip. The technique takes advantage of precise control of the coupled thermal (Joule heating), shear (electroosmosis), and electrical (electrophoresis) energies present at an array of probes afforded by the application of external electrical potentials. Temperature controllers and embedded thermal devices are not required. The chips can be easily and inexpensively fabricated using standard microarray printing methods combined with soft-lithography patterned PDMS fluidics, making these systems easily adaptable to applications using higher density arrays. Extensive numerical simulations of the coupled flow and thermal properties and microscale thermometry experiments are described and used to characterize the in-channel conditions. It was found that optimal conditions for SNP detection occur at a lower temperature on-chip than for typical microarray experiments, thereby revealing the importance of the electrical and shear forces to the overall process. To demonstrate the clinical utility of the technique, the detection of single-base pair mutations in the survival motor neuron gene, associated with the childhood disease spinal muscular atrophy, is conducted.