Extending micro-contact printing for patterning complex polymer brush microstructures

As a fast developing soft lithographic technique, the development of micro-contact printing (μCP) has exceeded the original aim of replicating poly(dimethylsiloxane) (PDMS) stamp patterns. Here we exploited several extended μCP strategies with various printing conditions (over-force or swelling induced physical deformation, and UV-Ozone treated chemical surface modification to a PDMS stamp), combining with surface initiated atom transfer radical polymerization (SI-ATRP), to pattern complex poly(N-isopropylacrylamide) (PNIPAAM) brush microstructures. These series of μCP strategies avoid the need for expensive and sophisticated instrumentation in patterning complex polymer brush microstructures that do not exist on the original PDMS stamp.     

Direct stamping and capillary flow patterning of solution processable piezoelectric polyvinylidene fluoride films

It is well known that the potential applications of polyvinylidene fluoride (PVDF) mainly come from the piezoelectricity and ferroelectricity of its polar β phase. Thus, we have investigated the effect of different preparation conditions namely evaporation temperature, type of solvent and additive to enhance the β crystal structures of PVDF thin film. Subsequently, facile and direct soft lithography technique; direct stamping and capillary flow were employed to demonstrate good pattern transfer of PVDF thin films. The piezoelectricity of the microstructure was characterized using piezoresponse force microscopy (PFM) where fairly good piezoresponse was obtained without further processing procedures i.e., annealing or applied pressure/electric field. As such, our solution processable and direct patterning of PVDF techniques offer facile and promising route to produce arrays of isolated microstructures with improved piezoelectric functionality.     

微孔-介孔复合分子筛的合成及应用研究进展

复合分子筛具有多个催化中心、比表面积大、热稳定性高等优点,近年来在国际学术界受到了广泛关注。概述了微孔-介孔复合分子筛的合成及应用研究进展,分析比较了各复合方法的优缺点,并展望了复合分子筛的发展趋势。     

Morphological and electrochemical characterization of a poly(3-methylthiophene)/PVDF composite

Composite electrodes were prepared via electrochemical polymerization of 3-methylthiophene in porous PVDF membranes of various thicknesses. The electrochemical properties were determined by cyclic voltammetry and charge-discharge tests and the possible correlation of the results with the morphology of the host membranes was examined. The best definition of n- and p-doping/undoping processes and the biggest capacitance (82 F g⁻¹) were obtained with a 27.5 μm-thick composite. Further characterization of this composite using electrochemical impedance spectroscopy revealed three behaviors associated with variation in the oxidation state of poly(3-methylthiophene) during transition from the n-undoping to p-doping states. The behavior of the charge transfer resistance and the double layer capacitance as a function of the applied potential were also determined.     

Reactive patterning via post-functionalization of polymer brushes utilizing disuccinimidyl carbonate activation to couple primary amines

Polymer brushes provide an exceptional route to surface functionalization due to their chemical and mechanical robustness, lack of large-area defects, and high density of functional groups. In spite of these benefits, the synthetic difficulty and complex surface structure associated with polymer brushes have hindered their utilization for constructing multifunctional, patterned surfaces. In this contribution we describe the use of a rapid and highly efficient polymer brush post-functionalization technique as a facile method for controlling surface functionality of polymer brushes. Poly(2-hydroxyethyl methacrylate) (PHEMA) brushes are post-functionalized via activation with N,N′-disuccinimidyl carbonate (DSC) and subsequent coupling to molecules containing α-amine moieties. This post-functionalization effectively tailors surface energy resulting in water contact angles ranging from 40° to 100° using different conjugate molecules. Furthermore, the solvent tolerance, insensitivity to reactant concentration, and rapid reaction time of the aminolysis reaction enable surface energy patterning of the polymer brushes through the use of “reactive” soft lithography. Finally, these surface energy patterns could be “developed” by exposure to gold nanoparticle solutions to yield surfaces with patterned nanoparticle density.     

Local direct and indirect reduction of electrografted aryldiazonium/gold surfaces for polymer brushes patterning

The patterning of conductive substrates by polymer brushes may be achieved by using successively scanning electrochemical microscopy (SECM) and atom transfer radical polymerization (ATRP). After the surface functionalization by a brominated aryldiazonium initiator, SECM allows the local reduction at the micrometer scale of the initiator grafted layer. Different channels sizes involved in charge transport within the initiator layers are evidenced by combining SECM, CV and observation of the aryl-grafted layer transformation. ATRP is performed on the SECM patterned substrate. Inside the pattern, the lower density of initiator decreases the polymer thickness. The pattern resolution is enhanced when the direct mode of the SECM is used instead of the mediated indirect mode.     

Submicron patterning of Ta, NiFe, and Pac-man type Ta/NiFe/Ta magnetic elements

Submicron patterning of Ta, NiFe, and Pac-man type magnetic elements of Ta/NiFe/Ta has been carried out in inductively coupled plasmas (ICPs) of Cl₂/Ar. Etch behavior was quite dependent on materials and plasma parameters. An ion-enhanced etch mechanism played a critical role for desorption of metal chloride etch products. Side-wall contamination with etch products was observed at a higher Cl₂ concentration (>50%). Compared to relatively damaged surfaces and profiles by the ion milling method, the ICP etching technique produced clear, smooth, and well-defined Pac-man type elements.     

CC—2SH粘结性前牙复合树脂研究

本文研制的CC-2SH粘结性前牙复合树脂由双组份液体底胶和双组份糊剂组成,含有PU-EAM树脂(二异氰酸酯改性EAM树脂)、EDMA、SiO_2、4-META等。本研究对合成方法、物理机械性能、粘结强度及多种影响因素等进行了实验研究。     

Atomic force microscope study of the rejection of colloids by membrane pores

An atomic force microscope (AFM) in conjunction with the colloid probe technique has been used to study the electrical double layer interactions between a 0.75 μm silica sphere and a polymeric microfiltration track etch Cyclopore membrane (nominally 1 μm) in aqueous solutions. The silica colloid probe was used to image the membrane surface (using the double layer mode) at different imaging forces in high purity water and at constant imaging force in sodium chloride solutions of different ionic strengths at pH 8. Force-distance measurements show clearly how the sphere detects the membrane surface. Quality of images produced from scanning the 0.75 μm silica particle across the surface deteriorates with increasing distance between the silica sphere and membrane surface. Such images were compared with those obtained from scanning a sharp silicon nitride tip over the membrane surface.     

PAN/PBA复合聚合物乳液性质的研究

用三种不同的加料方法和两种不同的加料顺序,制备了PAN/PBA复合聚合物乳液。测定了乳胶粒子的大小,分布,形态及胶体的表面张力,电导率,离心稳定性,电解质稳定性。发现单体全滴加法和AN先加入法的胶体表面张力大,电导率小,对电解质和离心稳定性较好。     

无皂乳液聚合制备三维有序聚合物大孔材料

采用氨催化水解正硅酸乙酯制备了单分散二氧化硅微球,通过透射电子显微镜观察微球的粒径及其单分散性。利用垂直沉积法制备二氧化硅胶体晶体,通过扫描电子显微镜观察其形貌,利用紫外-可见光分光光度计对其带隙结构进行表征。结合模板技术,采用无皂乳液聚合制得三维有序聚苯乙烯大孔材料,通过扫描电子显微镜观察结构的有序度。结果表明:聚苯乙烯大孔材料结构高度有序,形成开放的三维通道网络,为聚合物大孔材料在诸多领域的潜在应用提供了可能。     

纳米陶瓷材料

综述了纳米陶瓷材料的发展状况，介绍了纳米粉体的制备、团聚、烧结行为和烧结初期动力学模型。分析讨论了纳米陶瓷材料的显微结构、力学性质、增韧、增强机理，并对其发展态势进行了展望。     

电沉积耐磨复合镀层的研究与进展

综述了电沉积耐磨复合镀层的研究与进展,重点介绍了电沉积耐磨复合镀层的制备工艺、性能及其应用等.指出了目前所存在的问题,并对今后的研究提出了建议.     

PTFE在复合镀层中应用及进展

含有ＰＴＦＥ微粒的镀层可形成固体润滑膜,具有润滑性好,摩擦系数小,不粘着,易脱模等特性,综述了近年来ＰＴＦＥ复合镀层在耐磨,防腐,脱模等方面的应用及进展。     

多元复合柴油的制备和应用

综述多元复合柴油的特性和制备,简单阐述多元复合柴油在柴油车上的应用,多元复合柴油是一种微乳状液,它的作用已引起许多科学家的重视,有良好的推广应用前景。     

Template synthesis of structured titania using inverse opal gels

Inverse opal gels with varied content of acid groups were used as templates to synthesize structured crystalline titania materials. TiO₂ with opal, inverse opal, and gradient structure were obtained by altering composition of the gels and precursor concentration. The mechanism of the template synthesis by using opal gels was proposed.     

秸杆/聚丙烯复合材料

秸杆与聚丙烯复合制备了能替代木材使用的复合材料。考察了秸秆含量、界面处理剂用量对复合材料力学性能、流动性及形态的影响。结果表明：复合材料的拉伸强度和冲击强度随秸杆含量增加而下降,但下降幅度较小;而热性随秸杆含量增加而升高。处理剂效果较好,最佳用量为８ＰＨＲ。未经处理的复合材料随秸杆含量增加,其流动性先增加后逐渐降低;经处理过的复合材料流动性受秸杆含量影响不大。秸杆含量较少时,分散均匀;较多时有敛集     

微胶囊技术及其在复合材料中的应用

介绍了微胶囊技术的概念及其种类,归纳总结了微胶囊的表征方法。根据微胶囊近年来的研究,重点阐述了微胶囊技术在聚合物基复合材料损伤自修复过程中的应用研究。     

天然椰壳纤维及其增强复合材料

综述了天然椰纤维的一些基本性质和微观结构以及椰纤维在增强热固性树脂、热塑性树脂等领域中的研究和利用。     

复合材料制备用模具材料

以液态4，4′-二氨基二苯基甲烷四缩水甘油胺为基体树脂、四溴双酚A为增粘剂、1-氰乙基-2-甲基咪唑为固化剂，采用预浸法制成了复合材料。复合材料在中温(93℃)初固化后有足够的强度，在卸模后的高温(150℃x1h 180℃x2h)后固化过程中、在无支撑自由状态下能够保持自身尺寸的稳定性，可用作双马来酰亚胺基ACM的模具材料。