Near-zero-adhesion-enabled intact wafer-scale resist-transfer printing for high-fidelity nanofabrication on arbitrary substrates

There is an urgent need for novel processes that can integrate different functional nanostructures onto specific substrates,so as to meet the fast-growing need for broad applications in nanoelectronics,nanophotonics,and fexible optoelectronics.Existing direct-lithography methods are difficult to use on fexible,nonplanar,and biocompatible surfaces.Therefore,this fabrication is usually accomplished by nanotransfer printing.However,large-scale integration of multiscale nanostructures with unconventional substrates remains challenging because fabrication yields and quality are often limited by the resolution,uniformity,adhesivity,and integrity of the nanostructures formed by direct transfer.Here,we proposed a resist-based transfer strategy enabled by near-zero adhesion,which was achieved by molecular modification to attain a critical surface energy interval.This approach enabled the intact transfer of wafer-scale,ultrathin-resist nanofilms onto arbitrary substrates with mitigated cracking and wrinkling,thereby facilitating the in situ fabrication of nanostructures for functional devices.Applying this approach,fabrication of three-dimensional-stacked multilayer structures with enhanced functionalities,nanoplasmonic structures with~10 nm resolution,and MoS2-based devices with excellent performance was demonstrated on specific substrates.These results collectively demonstrated the high stability,reliability,and throughput of our strategy for optical and electronic device applications.

Direct fabrication of flexible tensile sensors enabled by polariton energy transfer based on graphene nanosheet films

A fundamental problem in the direct manufacturing of flexible devices is the low melting temperature of flexible substrates,which hinders the development of flexible electronics.Proposed here is an electron-cyclotron-resonance sputtering system that can batch-fabricate devices directly on flexible substrates under a low temperature by virtue of the polariton energy transfer between the plasma and the material.Flexible graphene nanosheet-embedded carbon(F-GNEC)films are manufactured directly on polyimide,polyethylene terephthalate,and polydimethylsiloxane,and how the substrate bias(electron energy),microwave power(plasma flux and energy),and magnetic field(electron flux)affect the nanostructure of the F-GNEC films is investigated,indicating that electron energy and flux contribute to the formation of standing graphene nanosheets in the film.The films have good uniformity of distribution in a large size(17 mm×17 mm),and tensile and angle sensors with a high gauge factor(0.92)and fast response(50 ms)for a machine hand are obtained by virtue of the unique nanostructure of the F-GNEC film.This work sheds light on the quantum manufacturing of carbon sensors and its applications for intelligent machine hands and virtual-reality technology.

Efficient nonfullerene organic solar cells with active layers fabricated by water transfer printing

Preparation of high-quality films plays an important role to achieve high-performance nonfullerene (NF) organic solar cells. NF active layer films are typically fabricated by spin coating. Novel fabrication methods to process the NF active layer are desirable to be compatible with large-area production. Herein, we report on the fabrication of NF active layer films via a water transfer printing method.This method delivers a uniform film with controllable film thicknesses. NF active layers of PDBD-T:ITIC and PBDB-T-2F:IT-4F were fabricated via the method to validate its effectiveness. Solar cells with the water transfer-printed active layers show comparable performance (up to 11.7%) to the cells with spin-coated active layers. Furthermore, NF solar modules containing 4-sub cells with the active area of 3.2 cm2 are also fabricated via the method. The module shows VOC of up to 3.4 V and a power conversion efficiency of 8.1% with the PBDB-T-2F:IT-4F active layer.

Evaluation on Heat Transferring Performance of Fabric Heat Sink by Finite Element Modeling

Considering the limitation in current manufacturing technology of commercial pin fin heat sinks,a new fabric heat sink has been designed. However,it is lack of an understanding of the heat transferring performance of this new kind of heat sink. In this study,the finite element method (FEM) was used to predict the heat transferring performance of fabric heat sink under the condition of natural convection and forced convection, and its heat transferring performance was compared with that of pin fin heat sink. The results showed that in the condition of natural convection the heat transferring performance of pin fin heat sink was better than that of fabric heat sink, and vice versa under the forced convection condition.

Water Repellent Finishing on Cotton Fabric via Atom Transfer Radical Polymerization

In order to enhance the water repellence property of cotton fabric, cotton fabric was grafted using hexafluorobutyl methacrylate( HFMT) monomer via atom transfer radical polymerization( ATRP) method. Water repellent cotton fabric was successfully prepared, and characterized by scanning electron microscopy( SEM),Fourier transform infrared spectroscopy( FTIR), and X-ray photoelectron spectroscopy( XPS). The SEM images of the HFMT-treated cotton displayed significant difference from the untreated one. FT-IR characterization of the HFMTtreated cotton indicated that HFMT was successfully grafted onto the surface of the cotton fabric. XPS analysis indicated that the fluorine element of the HFMT-treated cotton existing on the surface of the cotton fabric. The surface contact angle test as well as the water repellence rating test showed that the water repellence of the HFMTtreated cotton fabric was much better than that of the untreated cotton fabric. The surface contact angle of the HFMT-treated cotton fabric could reach( 132. 4 ± 2. 2) °,and the water repellence rating could achieve grade 3. The washing durability of the HFMT-treated fabric was also investigated. The surface contact angle of the HFMTtreated cotton fabric could reach( 121. 1 ± 2. 1) ° after 20 washing times. Furthermore, the whiteness, air permeability, breaking strength,and breaking elongation of the HFMT-treated cotton fabric decreased slightly compared with the untreated cotton fabric.Finally,cotton fabric with good water repellence property and excellent washing durability could be obtained with little effect on the intrinsic properties of cotton fabric.

An Improved Heat Transfer Model for Flame Resistant Fabric Used in Thermal Protective Clothing

An improved numerical heat transfer model considering pyrolysis effect is proposed to predict thermal performance of heat-resistant fabric subjected to radiant heat flux. The model incorporates the heat-induced changes in fabric thermophysical properties. The new model has been validated with data from modified Radiant Protective Performance (RPP) tests of flame-resistant cotton fabrics. Comparison with experimental data shows that the predictions of mass loss rates and temperature profiles within the charring material and skin simulant are in reasonably good agreement with the experiments. Results from the numerical model contribute to a better understanding of the heat transfer process within flame-resistant fabrics under high heat flux conditions, and also to establish a systematic method for analyzing heat transfer in other fibrous materials applications.

纬编双面移圈织物多层弹簧-质点结构模型构建与实现

纬编双面移圈织物工艺结构复杂多变,现有系统在进行设计开发时难以直观地展示出织物的组织结构特点。为实现纬编双面移圈织物的组织结构模拟,本文提出了一种纬编双面移圈织物多层弹簧-质点结构模型。首先建立了成圈、集圈、移圈线圈几何结构模型,接着分析了纬编双面移圈织物结构特征,并在传统弹簧-质点模型的基础上构建了多层弹簧-质点模型,然后采用牛顿第二定律和Velocity-Verlet数值积分法求解了多层弹簧-质点模型的最终位置,最终提出了一种纬编双面移圈织物结构模拟的算法流程。本文建立的多层弹簧-质点结构模型能够反映纬编双面移圈织物的组织结构,具有较好的结构模拟效果。

基于深度学习的面料密度回归预测

在实际面料设计和质量检测过程中,人工检测面料密度通常需要耗费大量的时间与人力资源,效率十分低下。为了解决这一问题,提出一种基于深度学习的面料密度回归预测方法。首先,基于迁移学习在改进后的VGG19上进行训练,在卷积层后面加入自适应平均池化层使输入图像大小不受限制,在全连接层加入SVD矩阵分解来减少计算时间。其次,删除分类层,将全连接层的输出作为最终模型的输出结果。在训练过程中,选用均方差损失函数,以某纺织企业提供的面料为数据集,进行对比实验和结果分析。结果表明:提出的方法相较于传统方法更加智能化,其面料密度计算误差约为5%,准确率为95.5%,具有一定的可行性。

织物-空气层-皮肤三维结构建模及其传热模拟

热防护服装是消防员面对火灾环境的重要屏障,为分析织物组织对其热防护能力的影响,构建了消防服外层阻燃织物的三维几何模型,并考虑实际着装状态建立“织物-空气层-皮肤”流固耦合传热模型。根据实验结果验证模型,并选取外界环境、织物组织结构及纱线导热系数进行参数研究,对比织物表面温度分布及真皮层热流密度、温度变化曲线。结果表明,该模型能较好地拟合实验结果,随着热暴露峰值温度的上升及纱线宽度的增大,纱线表面温度、真皮层热流密度、真皮层温度均上升。纱线的导热系数对真皮层温度影响较小。纱线宽度对真皮层温度的影响与热环境相关。有必要针对热暴露环境设计织物结构,在保障热防护性能的同时减小热防护服装质量,降低消防员热应激。

拉毛针织面料热传递性能的有限元仿真

为探究拉毛针织面料的毛羽对面料热传递性能的影响规律,提出了一种预测拉毛针织面料热传递性能的方法,建立了针织线圈-毛羽层模型,在此基础上对拉毛针织面料的热传递性能进行有限元仿真分析,并通过实验验证模型的有效性。首先对实验面料进行测量,得到织物的几何结构参数,利用SolidWorks专业建模软件建立织物的针织线圈结构,利用ANSYS DesignModeler建立织物的毛羽层;然后借助有限元分析软件ANSYS Fluent,根据模拟环境设置边界条件,进行迭代运算,得到该模型的温度分布云图;最后将仿真模拟的结果与实验测试结果进行对比,对模型的有效性进行验证。研究结果表明:拉毛针织面料的模拟热阻值与实验热阻值相关系数接近0.993,最大差异小于17.7%,表明该有限元模型具有一定的可行性;拉毛针织面料的表面毛羽密度越高,织物的热阻值越大,但是毛羽密度达到一定范围后,织物热阻值发生较小变化。

基于红外图像的织物水分动态传递性能测定方法

为提升织物水分动态传递性能测定的准确性,解决图像技术测定过程中织物润湿区域提取困难的问题,选用了红外热像仪对织物水分动态传递过程进行观测,构建了一款基于红外图像的织物水分动态传递性能测定系统。系统可将录制的织物水分动态传递红外成像视频按设定的参数依次进行图像提取、分割、双边滤波处理和二值化处理,并将处理得到织物水分润湿图像按照像素比例自动换算成织物实际润湿面积值输出,以自动测定织物水分动态传递性能。采用该系统测量了6种织物试样的水分动态传递性能,验证了该测定系统的准确性,并分析了6种织物的水分传递性能差异。结果表明:该测定系统能计算出织物水分动态传递过程中各个时刻的润湿面积,且结果准确性高。测试数据分析发现,织物水分传递初期的速度与织物面密度和总紧度呈明显负相关,与理论分析一致。

基于VARTM的碳纤维单向与三维编织混杂织物树脂灌注工艺

为探究碳纤维单向与三维编织混杂增强环氧树脂基复合材料地铁转向架侧梁的树脂灌注成型工艺,首先基于渗透率理论模型采用非饱和径向流法分别测试得到碳纤维单向与三维编织织物的渗透率。通过数值模拟的方法对典型复合材料方形管结构进行缩比建模与网格划分,并利用PAM-RTM软件对树脂灌注成型过程进行仿真分析,预测了制备复合材料方管所需的灌注时间、灌注压力以及树脂流动过程缺陷的产生。最后根据模拟的灌注方案通过真空辅助树脂传递模塑(VARTM)成型工艺制备了碳纤维单向和三维编织混杂织物增强环氧树脂复合材料方管结构件。结果表明,通过PAM-RTM模拟VARTM工艺制备复合材料方管时树脂的流动,预测得到灌注时间为3897 s,VARTM工艺实际制备复合材料方管的灌注时间为4052 s,误差约为3.8%,在合理误差范围内。方管内部灌注压力随着与注胶口距离的增加而逐渐减小。模拟与实验的误差可能是由于实际铺层和灌注过程中树脂流动引起织物的剪切变形以及真空度的差异导致渗透性能产生变化。仿真模拟和实际制备复合材料方管均无明显缺陷产生,证明径向法织物渗透率的理论模型计算测试和仿真结果具有可靠性。

基于稳态热湿传递模型的单层织物孔隙率最优决定反问题

在稳态热湿传递模型的基础上,提出了一个单层织物的孔隙率最优决定反问题,通过优化织物的孔隙率参数以提高服装的热湿舒适性。使用蝙蝠算法求解单层织物的稳态热湿传递模型,得到温度和水汽浓度的分布;在此基础上,以高温天气下单层织物的散热性和透湿性最佳为目标,提出了单层织物孔隙率最优决定反问题;使用热阻和湿阻衡量织物的散热性和透湿性,将该反问题描述为一个热阻和湿阻最小优化问题,对热阻和湿阻设置不同的权重,将其转化为单目标优化问题,并使用蝙蝠算法求解。使用棉、羊毛、涤纶等3种常见的织物进行数值实验,结果表明:该反问题存在最优解,求解该反问题可得到使单层织物散热透湿性能达到最佳的孔隙率最优值;蝙蝠算法求解热湿传递模型正问题和反问题的效率高于常用的粒子群优化算法。该研究拓展了通过优化织物参数提高服装热湿舒适性的研究内容,可为高温天气下服装热湿舒适性优化设计提供一定的理论支持。

影响植物蒸染转印染着色因素实验研究

植物转印染拥有古老而深厚的历史文化底蕴,其工艺过程不会产生污染物质,属于绿色环保的染整技术,符合当下大环境的政策要求和市场需求。为了提高植物转印染的品质与效率,进而拓展其在纺织产品中的应用,探索其在织物上的染色效果是一个重要的研究课题。文章通过系列的变量实验分析出不同因素对植物蒸染转印染着色效果所造成的影响,得出科学的一般结论,可直接应用于后期更深层次的植物蒸染转印染研究与应用中。

基于一磷酸腺苷的RAFT接枝棉织物的结构和阻燃性能

采用可逆加成断裂链转移自由基聚合(RAFT)方法,基于纤维基二硫代酸酯类RAFT链转移剂(Cell-CTA),以偶氮二异丁腈为引发剂,以改性一磷酸腺苷(AAMP)为阻燃单体,在纯棉织物上进行RAFT接枝聚合改性,制备了接枝阻燃棉织物(Cell-g-PAAMP)。采用红外光谱、扫描电镜、拉曼光谱等方法对Cell-g-PAAMP的化学结构、表面形貌及其燃烧后残炭的形态和石墨化程度进行了表征。采用热重分析仪、数显氧指数测定仪、织物强力仪、透气性能测试仪对Cell-g-PAAMP的阻燃性能和物理机械性能进行了分析。Cell-g-PAAMP红外光谱中,1199 cm^(-1)处新出现P=O双键的伸缩振动峰,说明已成功制备Cell-g-PAAMP。扫描电镜和拉曼光谱结果表明,Cell-g-PAAMP表面粗糙,有颗粒状物质附着于表面,燃烧后残炭形态保持基本完整且结构致密,石墨化程度提高。与纯棉织物对比,Cell-g-PAAMP初始分解温度降低,热稳定性提高,极限氧指数提高,获得了良好的阻燃效果。Cell-g-PAAMP透气性和断裂强力下降,但断裂伸长率却大幅增加。

Membranes for extracorporeal membrane oxygenator(ECMO): History,preparation, modification and mass transfer

Extracorporeal membrane oxygenator(ECMO) has been in development for nearly 70 years, and the oxygenator has gone through several generations of optimizations, with advances from bubble oxygenators to membrane oxygenators leading to more and more widespread use of ECMO. Membrane is the core of a ECMO system and the working mechanism of membrane oxygenator depends on the membrane material,from PDMS flat membrane to PMP hollow fiber membrane, which have experienced three generations.Blood compatibility on the surface of the membrane material is very vital, which directly determines the use duration of the oxygenator and can reduce the occurrence of complications. The mechanism of mass transfer is the basis of oxygenator operation and optimization. This review summarizes the membrane development history and preparation technology, modification approaches and mass transfer theory in the process of oxygen and blood exchange. We hoped that this review will provide more ideas for the study of gas blood exchange membrane.

Bifunctional Asymmetric Fabric with Tailored Thermal Conduction and Radiation for Personal Cooling and Warming

Personal thermal management is emerging as a promising strategy to provide thermal comfort for the human body while conserving energy.By improving control over the heat dissipating from the human body,personal thermal management can provide effective personal cooling and warming.Here,we propose a facile surface modification approach to tailor the thermal conduction and radiation properties based on commercially available fabrics,to realize better management of the whole heat transport pathway from the human body to the ambient.A bifunctional asymmetric fabric(BAF)offering both a cooling and a warming effect is demonstrated.Due to the advantages of roughness asymmetry and surface modification,the BAF demonstrates an effective cooling effect through enhanced heat conduction and radiation in the cooling mode;in the warming mode,heat dissipation along both routes is reduced for personal warming.As a result,a 4.6℃ skin temperature difference is measured between the cooling and warming BAF modes,indicating that the thermal comfort zone of the human body can be enlarged with one piece of BAF clothing.We expect this work to present new insights for the design of personal thermal management textiles as well as a novel solution for the facile modification of available fabrics for both personal cooling and warming.

A STUDY OF TRANSMISSION OF MOISTURE THROUGH FABRICS

Based on the Dynamic Dress Model which can simulate the body core temperature and skintemperature,as well as body sweating,this paper holds a further inquiry into the new method formeasuring heat resistance of fabrics and moisture transmission in terms of“clo”unit andpermeability index“im”.It is found out that the values of Tex of warp and weft have the greatestinfluence on permeability index im and when the thread count increases to a certain limit,thepermeability index“im”is in direct proportion to thread count.

INFLUENCE OF PROCESSING PARAMETERS AND POWDER BINDER CONTENT ON PROPERTIES OF HIGH LOFT NONWOVEN FABRICS

In this paper, the influence of processing parameters and powder binder content was studied and analysed on the properties of high loft nonwoven fabrics mainly using statistical analysis method. The relationship between the bulkiness and the warmth retention property was also tested. The analytical results reveal that the increase of the powder content, heating temperature and pressure will affect the tensile strength of nonwovens. Moreover, there are interactions between these parameters. The compression properties only change a little for a powder binder content of 15％—20％. However, with the increase of the heating temperature and pressure, the bulkiness and compression rate will reduce significantly. For the bulk density of high loft nonwoven fabrics, there exists a heat transter mechanism of air convection, but the higher the bulkiness of nonwovens, the larger the thickness and the better the warmth retention property of nonwoven fabrics.

An Investigation on Water Transmission Through Two-layer Knitted Fabrics

The aim of this paper is to investigate water transmissionproperties of two-layer weft knitted fabrics and somerelated factors.The author prepared some experimentalfabrics with specific yarns and stitch densities,and mea-sured water vapor permeating rate through the fabricsand liquid water transferability from inner to outerlayer.Results show that the permeating rate is closelyrelated to porosity within fabric while the transferabilitydepends mainly upon the water absorbabilities of fiberson two layers and the degree or their difference.