加工温度对线型低密度聚乙烯/聚苯乙烯薄膜微观形态及光散射性能的影响

采用微层共挤出制备了16层(线型低密度聚乙烯(LLDPE)/聚苯乙烯(PS))共混物/聚甲基丙烯酸甲酯(PMMA)交替层状材料,将PMMA层剥去后得到从皮层和芯层不同位置的LLDPE/PS薄膜。研究加工温度对皮层和芯层薄膜微观形态和光散射性能的影响。微观形态观察显示,对于200℃制备的皮层和芯层LLDPE/PS薄膜中PS均以球状分散,皮芯层差异较小。随着加工温度的升高,PS分散相开始沿挤出方向变形,特别在皮层薄膜中的变形尤为显著,皮芯层形态差异逐渐增大。光散射性能测试结果表明,加工温度升高后,试样的光散射各向异性程度增加,透光性降低,雾度均在93%左右,同时皮芯层的光学性能差异逐渐增大。说明较低的加工温度更有利于制得均匀结构和光散射性能优异的LLDPE/PS光散射材料。     

嵌段共聚物PEO-b-PS与聚苯乙烯共混薄膜的表面形貌及性能

通过原子转移自由基聚合(ATRP)制备了嵌段共聚物聚氧化乙烯(PEO-b-聚苯乙烯(PS)),将PEO-b-PS与PS溶液共混成膜,使用接触角测试仪(CA)和原子力显微镜(AFM)考察了PEO-b-PS含量与共混薄膜表面形貌及性能之间的关系。研究发现,嵌段共聚物在薄膜中发生微相分离并在薄膜表面形成PEO微相区,随PEO-b-PS含量增加,薄膜表面PEO相区尺寸增大,但分布密度下降。通过共混薄膜表面形貌的变化,解释了共混薄膜的亲水性和表面张力随PEO-b-PS含量增加的变化趋势。     

聚丙烯酸对含聚氧化乙烯链段嵌段共聚物微相分离形貌的调控作用

采用原子转移自由基聚合(ATRP)制备了两嵌段共聚物聚氧化乙烯-b-聚苯乙烯(PEO-b-PS)和三嵌段共聚物聚氧化乙烯-b-聚苯乙烯-b-聚丙烯酸丁酯(PEO-b-PS-b-PBA),再将聚丙烯酸(PAA)分别与PEO-b-PS和PEO-b-PS-b-PBA进行溶液共混和旋涂成膜,通过原子力显微镜研究了PAA对2种嵌段共聚物薄膜微相分离形貌的调控作用。结果表明,PEO-b-PS/PAA共混薄膜呈现PEO/PAA为分散相以柱状形态垂直分布在PS连续相中的微相分离形貌,柱状微区尺寸随着PAA含量及相对分子质量的增加而不断增大。当PAA质量分数达到30%后,PEO/PAA分散相向层状形态转变。PEO-b-PS-b-PBA与PAA共混后,PEO/PAA相区从原先平行于薄膜表面排列的层状形态向随机取向的柱状形态转变,PS微相区在薄膜表面形成细小的锥状突起,随着PAA质量分数增加,PEO/PAA柱状微区向薄膜表面垂直排列取向得到增强,PS微相区的突起程度降低。     

PCL-b-PMMA/PEO共混薄膜的微相分离形貌

通过聚氧化乙烯(PEO)与聚己内酯-聚甲基丙烯酸甲酯嵌段共聚物(PCL-b-PMMA)的共混来调节聚己内酯(PCL)与聚甲基丙烯酸甲酯(PMMA)嵌段的微相分离行为。采用原子力显微镜研究了PEO的质量分数和相对分子质量对PCL-b-PMMA/PEO共混薄膜微相分离形貌的影响。结果表明,共混薄膜形成了以PMMA/PEO为连续相,PCL呈柱状微区垂直于薄膜表面的微相分离形貌,PMMA/PEO链段无法在PCL柱状微区上方形成完全覆盖,导致薄膜表面形成许多孔洞。随着PEO含量增加,PCL链段聚集趋势增强,柱状微区尺寸不断增大;随着PEO相对分子质量的增加,PMMA/PEO在PCL微区上方形成的有效覆盖减少,薄膜表面的孔洞数量和尺寸增大;当PEO与不同嵌段比PCL-b-PMMA共混后,随嵌段共聚物中PCL链段体积分数增加,柱状微区向层状形态转变,薄膜表面孔洞消失。     

PMMA/SAN/MBS共混物的结构与性能

通过熔融共混法制备了聚甲基丙烯酸甲酯/聚(苯乙烯-丙烯腈)/甲基丙烯酸甲酯-丁二烯-苯乙烯聚合物(PMMA/SAN/MBS)共混物。对共混物进行了力学性能测试,结果表明,MBS的加入显著提高了共混物的冲击韧性,PMMA与SAN的配比对其冲击韧性影响不大;采用光电雾度仪和透射电镜(TEM)对共混物的光学性能和结构进行了表征,结果表明,PMMA/SAN/MBS共混物的透光率随MBS含量的增加而降低;PMMA/SAN的质量比为50/50时,MBS含量对共混物透光率的影响最小;TEM结果表明,MBS在基体中分散均匀;用光学显微镜等手段对共混物耐刮擦行为进行了研究,结果表明,MBS的加入在一定程度上降低了共混物的耐刮擦性能。     

SiO2纳米粒子填充PS/PMMA共连续共混物的应力松弛行为

采用流变测试和扫描电子显微镜技术,考察了亲水性SiO2纳米粒子对具有共连续结构的聚苯乙烯(PS)/聚甲基丙烯酸甲酯(PMMA)(体积比50/50)共混物在步阶剪切应变下应力松弛行为的影响。研究表明,PS/PMMA共混物呈现两步应力松弛行为,即来源于本体聚合物的较快的松弛以及来源于界面的较慢的松弛。SiO2粒子的加入细化了共混物的形态尺寸,加速了共混物第二阶段的松弛行为。同时,实验结果进一步表明,填充共混物应力松弛行为的加快主要是由于SiO2的加入引起形态细化造成的,而并非组分粘弹性的变化。     

新型萘二甲酰亚胺基半导体/绝缘聚合物共混薄膜的微结构和电荷传输研究

采用新型萘二甲酰亚胺基半导体聚合物FN2200与绝缘聚合物聚苯乙烯(PS)通过溶液相共混,并采用旋涂法制备共混薄膜的有机场效应晶体管(OFET)。发现在FN2200中加入少量PS可显著提升共混薄膜器件的电子迁移率,然而随着PS含量的增加,载流子迁移率将急剧降低。通过氧等离子体刻蚀结合紫外-可见光吸收谱测量发现,FN2200/PS共混薄膜存在清晰的相分离结构,FN2200组分富集在在薄膜表面层而PS成分沉积在薄膜底部区。掠入射X射线衍射(GIXRD)结果发现,在FN2200中添加PS成分促使FN2200骨架链倾向于采取edge-on堆积方式,有利于载流子沿有机/介电层界面的横向传输。基于薄膜微结构表征结果,系统地解释了共混薄膜的OFET性能随PS含量的变化关系和内在机制。     

聚丙烯大分子表面改性剂PP-g-PMMA的制备及应用

以马来酸酐为桥联剂,通过其与含端羟基PMMA的偶合反应,合成了新型大分子表面改性剂PP-g-PMMA,用IR、NMR、TG、DSC对接枝物进行表征,并通过共混研究了接枝物对聚丙烯的表面改性。结果表明,PP-g-PMMA的热稳定性随着PMMA侧链的含量增加及分子量的增大而略有下降,PMMA侧链的存在降低了PP主链的结晶能力,阻碍其形成较为完整的β晶相;所合成的接枝物具有表面外迁性,可富集于共混物薄膜的表面,有望作为PP的大分子长效表面改性剂使用。     

生物可降解PLA/PCL共混包装薄膜的结构与阻隔性能研究

为了改善包装用聚乳酸(PLA)薄膜的韧性,本文选用生物可降解高分子材料聚己内酯(PCL)与其进行共混,并加入柠檬酸三丁酯(TBC)对这两组分进行增容。通过溶液铸涂法制备不同配比的PLA/PCL共混包装薄膜,研究了PCL的加入对PLA薄膜的结构及性能的影响。X射线衍射仪(XRD)测试结果表明,随着PCL的加入,可以提高PLA/PCL共混包装薄膜的相对结晶度。热重分析法(TG)测试表明,PCL的加入使PLA的起始分解温度降低,但是其终止分解温度有所升高。通过对共混薄膜的阻隔性能测试可知,PCL的加入,使共混薄膜的水蒸气和氧气的渗透性降低,其阻隔性能得到改善。从光学性能测试中发现,增加PCL的含量使共混薄膜的透光率降低。     

PS/POE增容母料对SAN/PS/POE共混物结构及性能的影响

利用Friedel-Crafts烷基化反应制备了聚苯乙烯(PS)/聚烯烃弹性体(POE)(50/50,质量比,下同)增容共混物。抽提结果显示,该共混物中PS-g-POE接枝共聚物的质量分数为28.3%。以该共混物作为增容母料,考察其对苯乙烯-丙烯腈共聚物/聚苯乙烯/聚烯烃弹性体(SAN/PS/POE)共混体系力学性能、热稳定性、微观结构等方面的影响。结果表明,固定SAN/PS/POE共混物组成,部分PS、POE组分被增容母料取代后,共混物性能得到明显提高,共混物SAN/PS/POE(50/20/30)与SAN/母料/POE(50/40/10)相比,其拉伸强度从10.8 MPa上升至21.0 MPa,断裂伸长率从1.6%上升至22.3%;热重分析显示,增容共混物中易分解组分的热稳定性提高,共混物SAN/PS/POE(20/10/70)与SAN/母料/POE(20/20/60)相比,其易分解组分的分解温度从413.6℃提高到425.1℃;从扫描电镜(SEM)照片可以看出,增容共混物中分散相更均匀细小。     

石墨烯及其复合自支撑膜研究进展

作为新一代超级电容器电极材料,石墨烯具有比表面积高、化学稳定性和力学性能优异等特点。但是,制备致密度高、结构稳定性好的石墨烯电极时往往需要添加黏结剂,而黏结剂的引入会削弱电极材料的电化学性能,制备石墨烯及其复合自支撑膜是解决该问题的有效手段之一。介绍了石墨烯自支撑膜的成膜方法,包括抽滤诱导自组装、气液界面自组装、涂覆法和层层自组装等传统方法,以及一种新颖的低温旋切成膜方法。着重总结了导电聚合物/石墨烯、金属氧化物/石墨烯及三元石墨烯基复合膜的研究进展。提出了石墨烯及其复合自支撑导电膜未来的发展趋势,包括开发新型、简便、量产的薄膜电极制备技术、控制石墨烯及其复合自支撑膜的微观结构、将各种成膜方法运用于制作便携式电子器件或柔性电池中等。     

Gradient solvent vapor annealing of block copolymer thin films using a microfluidic mixing device

Solvent vapor annealing (SVA) with solvent mixtures is a promising approach for controlling block copolymer thin film self-assembly. In this work, we present the design and fabrication of a solvent-resistant microfluidic mixing device to produce discrete SVA gradients in solvent composition and/or total solvent concentration. Using this device, we identified solvent composition dependent morphology transformations in poly(styrene-b-isoprene-b-styrene) films. This device enables faster and more robust exploration of SVA parameter space, providing insight into self-assembly phenomena.     

Template-assisted growth of nominally cubic (100)-oriented three-dimensional crack-free photonic crystals

Three-dimensional (3D) photonic crystals (PhCs) are now beginning to acquire functionality via the use of dopants and heterostructures. However, the self-organized fabrication of large-area single crystals that are free of cracks and stacking faults has remained a challenge. We demonstrate a technology for the fabrication of (100)-oriented thin film 3D opal PhCs that exhibit no cracks over areas having no intrinsic size limit via a modified template-assisted colloidal self-assembly approach onto a patterned substrate. This technology potentially makes available large area regions of single photonic crystal, which can be used for optoelectronic devices.     

纳米材料形貌和性能调控的仿生自组装研究进展

纳米材料在纳米尺度展现出的特殊性质, 相较于宏观尺度材料表现出众多优异特性, 在力学、声学、光学、磁学、电学、热学等各种领域具有良好的应用前景。纳米材料的仿生自组装技术模拟活体生命活动, 使纳米材料基于非共价键的相互作用, 自发形成稳定结构, 现已成为制备纳米材料的主要方法之一。仿生自组装技术是“自上而下”方法中的重要技术手段, 这种合成方式有望代替传统的“自上而下”加工技术, 实现单个原子或分子在纳米尺度上构造特定结构和功能的器件。另外, 仿生自组装技术虽然以化学过程为主, 但又有物理过程, 并且结合了“仿生学”的优点, 具有定向构造纳米材料的特点, 是众多交叉学科的热门研究手段。本文重点介绍了纳米材料在形貌和性能调控中不同的仿生自组装合成策略, 包括屏蔽效应的位相选择自组装、双相界面协同效应的仿生自组装、场诱导定位效应的功能器件一体化制备、光诱导自组装以及羟基氢键驱动的分相自组装, 总结了仿生自组装纳米材料的特性, 归纳了自组装技术在传感器、表面拉曼散射、生物医疗等领域的应用, 并对纳米材料仿生自组装技术的发展前景进行了展望。     

分子自组装研究进展

分子自组装在生物工程技术上的建模、分子器件、表面工程以及纳米科技领域已经有很广泛的应用.在未来的几十年中,分子自组装作为一种技术手段将会在新技术领域产生巨大的影响.在这篇文章里,我们介绍了分子自组装技术的定义、基本原理、分类、影响因素、表征手段等,并阐述了分子自组装技术目前的研究进展,展望了分子自组装技术的应用前景.     

Nanostructured carbon nanotubes/copper phthalocyanine hybrid multilayers prepared using layer-by-layer self-assembly approach

In this report, we demonstrate a convenient method of fabricating single-walled carbon nanotubes/organic semiconductor hybrid ultrathin multilayers using a layer-by-layer self-assembly approach. Single-walled carbon nanotubes were solubilized by water-soluble cationic alcian blue pyridine variant and anionic copper phthalocyanine-3,4′,4″,4′″-tetrasulfonic acid tetrasodium salt, which were then utilized for electrostatic layer-by-layer multilayer fabrication. The solubilization ability of single-walled carbon nanotubes was studied in water by UV-vis absorption spectroscopy. The composites were highly dispersed owing to the π-π interactions. In situ surface plasmon resonance spectroscopy during the layer-by-layer multilayer fabrication indicated a stepwise increase in reflectivity, indicating the successive formation of nanostructured hybrid ultrathin films. Cyclic voltammetry revealed that the electroactivity of the hybrid film was enhanced by the incorporation of single-walled nanotubes.     

Challenges and breakthroughs in recent research on self-assembly

Abstract

The controlled fabrication of nanometer-scale objects is without doubt one of the central issues in current science and technology. However, existing fabrication techniques suffer from several disadvantages including size-restrictions and a general paucity of applicable materials. Because of this, the development of alternative approaches based on supramolecular self-assembly processes is anticipated as a breakthrough methodology. This review article aims to comprehensively summarize the salient aspects of self-assembly through the introduction of the recent challenges and breakthroughs in three categories: (i) types of self-assembly in bulk media; (ii) types of components for self-assembly in bulk media; and (iii) self-assembly at interfaces.     

A new approach to molecular devices using SAMs,LSMCD and Cat-CVD

This paper proposes a new technology for the fabrication of molecular devices using nanotechnology based on liquid and surface sciences recently developed, such as the direct patterning of solid surfaces using the difference of hydrophobic and hydrophilic properties of self-assembled mono-layers and self-assembly films of metal nanoparticles, the fine fabrication of films by the method of Liquid Source Misted Chemical Deposition, and the Langmuir–Blodgett self-assembly films. In these liquid-based technologies, various kinds of organic compounds in solutions, including biological systems, can be used as functional materials in molecular devices. In addition, it has been found that the insulating inorganic films obtained by catalytic chemical vapor deposition are quite effective in the protection of molecular devices against water and/or oxygen. We confirm, from the experimental results presented in this report, that this new approach is practically promising in future.     

Controlling self-assembled structure of Au nanoparticles by convective self-assembly with liquid-level manipulation

Microwire networks composed of noble metal particles are promising for the use of transparent conductive films. Bottom-up approaches can offer a route to establishing a fabrication technique that is robust and cost-effective, and template-assisted self-assembly techniques are widely used. However, they require additional processes to prepare templates and generally suffer from the difficulty in a large-scale fabrication. A template-free technique thus waits to be developed.In the present study, we explore a template free technique to fabricate colloidal networks of Au nanoparticles. We combine the convective self-assembly method with a liquid-level manipulation scheme in which the suspension is periodically pumped out. By using the technique, we successfully fabricate stripe, grid, and triangle patterns with controlled periodicity and examine the relationship between operation parameters and the resultant structures. We then measure the transparency and conductivity of a grid pattern to demonstrate the property as the transparent conductive film.     

Contact-induced crystallinity for high-performance soluble acene-based transistors and circuits

The use of organic materials presents a tremendous opportunity to significantly impact the functionality and pervasiveness of large-area electronics. Commercialization of this technology requires reduction in manufacturing costs by exploiting inexpensive low-temperature deposition and patterning techniques, which typically lead to lower device performance. We report a low-cost approach to control the microstructure of solution-cast acene-based organic thin films through modification of interfacial chemistry. Chemically and selectively tailoring the source/drain contact interface is a novel route to initiating the crystallization of soluble organic semiconductors, leading to the growth on opposing contacts of crystalline films that extend into the transistor channel. This selective crystallization enables us to fabricate high-performance organic thin-film transistors and circuits, and to deterministically study the influence of the microstructure on the device characteristics. By connecting device fabrication to molecular design, we demonstrate that rapid film processing under ambient room conditions and high performance are not mutually exclusive.