Metastable patterning of plasma nanocomposite films by incorporating cellulose nanowhiskers

A new method is presented for developing patterned, thin nanocomposite films by introducing cellulose nanowhiskers during the pulsed plasma polymerization of maleic anhydride. Metastable film structures develop as a combination of dewetting and buckling phenomena. By controlling the maleic anhydride monomer to cellulose nanowhisker weight ratio, the whiskers can be incorporated into a homogeneously covering patterned polymer film. Excess nanowhiskers are required to prevent complete dewetting and deposit dimensionally stable films. The formation of anchoring points is assumed to stabilize the film through a "pinning" effect to the substrate. The latter control the in-plane film stresses, similar to the effects of surface inhomogeneities such as artificial scratches. The different morphologies are evaluated by optical microscopy, AFM, contact angle measurements, and ellipsometry. Further analysis by infrared spectroscopy and XPS suggests esterification between the maleic anhydride and cellulose moieties.     

General Synthesis of Two‐Dimensional Patterned Conducting Polymer‐Nanobowl Sheet via Chemical Polymerization

Summary: A general method for the generation of two‐dimensional (2D) ordered, large‐area, and liftable conducting polymer‐nanobowl sheet has been demonstrated via chemical polymerization for the first time. The sheet is made using the monolayer self‐assembled from polystyrene (PS) spheres at the aqueous/air interface as template, followed by depositing conducting polymer on the part of PS monolayer submerging in the aqueous phase via chemical polymerization, and core extraction. During the process of polymerization, no substrate is required, which caused the as‐prepared patterned conducting polymer sheet can be easily lifted‐off and deposited, in full size, on any flat substrate. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectrum were used to characterize the products.

Morphology of the polyaniline‐CSA nanobowl sheet.     

Biomimetic fabrication of 3D structures by spontaneous folding of tapes

This paper describes a biomimetic strategy for the fabrication of 3D structures-including an electrically functional light detector-modeled on the folding of biological macromolecules into globular shapes. The process started by fabricating precursors to 3D, millimeter-sized structures using flexible polymer tapes. These tapes were patterned with metal features supporting liquid solder, crimped into strings of 3D corrugations, and attached to flat polymer tapes to generate linear 3D structures. Capillary interactions between droplets of molten solder on adjacent faces of the crimped tapes resulted in folding of the precursors into quasi-3D and truly 3D structures.     

Hybrid protein-lipid patterns from aluminum templates

An aqueous aluminum liftoff process suitable for fabrication of hybrid patterns of protein and supported lipid membrane on silica surfaces is described. Patterned aluminum thin films, which can be produced by conventional optical or electron beam lithography, are employed as sacrificial protecting layers to define the geometry of the protein-lipid patterns. The aluminum is lifted off in a mildly basic aqueous solution, which preserves the integrity of bound protein layers. The newly exposed substrate can then be filled with supported membrane by exposure to an aqueous vesicle suspension. The final substrate consists of patterned protein and lipid membranes with spatial resolution determined by aluminum patterns, down to 200 nm line widths in this case. Inorganic surfaces were characterized by atomic force microscopy and X-ray photoelectron spectroscopy while supported bilayers and protein patterns were characterized by epifluorescence microscopy.     

Influence of individual ionic components on the agglomeration kinetics of silver nanoparticles

We demonstrate an original and powerful concept for elaborating spontaneous, high fidelity patterns of nanoporosity from nanoscale building blocks using patterned surface chemistry (i.e., "surface energy gating") to corral the growth of colloidal structures at a solid surface. Composite films consisting of polymethylsilsesquioxane nanoparticles uniformly dispersed in polypropylene glycol polymer were examined at temperatures beyond the decomposition of the polymer as a function of the substrate surface energy to clarify nanoparticulate ensemble behavior. The principle behind this colloidal assembly can be understood by taking into consideration the entropy and enthalpy dictating the mutual interactions between substrate surface, polymeric solvent, and dispersed colloids in the decomposition regime. The relevance of this research is shown by demonstrating how the principle of surface energy gating can be utilized to achieve spontaneous and controllable spatial patterns of nanoporous, high surface area thin films in a cost-effective and energy-efficient manner via brief thermal exposure. The simplicity and general nature of this methodology are further exemplified by showing the facility with which high-contrast fluorescent bioconjugate arrays can be prepared from nanoporous organosilicate patterns.     

准二维钙钛矿太阳能电池的研究进展

新型有机-无机杂化二维（2D）钙钛矿具有优良的光电性能、 结晶性和稳定性, 在太阳能电池领域引起广泛关注. 相比于三维（3D）钙钛矿, 由于有机间隔阳离子（OSC）的引入形成独特的层状晶体结构赋予了材料特殊性质: （1） 多层量子阱结构促成材料各项异性的光电性质; （2） 间隔阳离子改变前驱体团簇状态, 实现溶液中高质量的结晶; （3） 间隔层的疏水性质和抑制离子迁移作用, 从本源上改善了钙钛矿的稳定性. 近年来, 针对准2D钙钛矿太阳能电池（准2D-PSCs）展开了广泛研究, 并取得了一系列重要研究成果. 本文从准2D钙钛矿材料的晶体结构与取向、 相分布、 光电性质到器件的能量转化效率与稳定性等方面, 综合评述了近年来准 2D-PSCs的最新研究进展, 总结了晶体结构-材料性质-电池性能之间的作用机制, 并进一步展望了未来研究的趋势.     

Effect of chain length and substrate temperature on the growth and morphology of n-alkane thin films

Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and microscopy has been used to study the orientational morphology of thin films of the linear alkanes n-C36H74 and n-C60H122, prepared by vacuum deposition onto NaCl (001) surfaces at ambient and elevated substrate temperatures. The orientational morphology, specifically, the nature of domains with lateral and normal orientation, is explored as a function of the chain length and the substrate temperature. It is found that the longer n-C60H122 molecules are laterally oriented on the substrate surface within the investigated substrate temperatures but that the morphology of these thin films varies with substrate temperature. The shorter n-C36H74 molecules are partially laterally oriented at low substrate temperature and are completely normally oriented at high substrate temperature. The relative magnitude of "side-by-side" and "end-to-end" intermolecular interactions leads to the formation of highly ordered alkane structures with a high aspect ratio. The formation of complex, nanoscale orientational morphologies are rationalized by considering kinetic and thermodynamic effects, in particular, the relative enthalpic and entropic contributions to the free energy associated with the different molecular orientations.     

热诱导金属/聚合物膜系图案化控制的研究

近年来 ,在简单体系上形成复杂规则的图案已引起诸多学者的注意 ,其中以聚合物为母体的体系发展了模板、局部紫外照射和激光诱导等一系列技术 ,从而得到可控的表面图案[1～ 6] .本文用激光刻蚀法对溅射在聚合物膜上的金属薄膜进行处理 ,在热诱导情况下使金属 /聚合物膜系表面产生了规则的图案 .薄膜热应力的可控释放作用和激光刻蚀造成的区域局限作用被认为是诱导这种可控图案产生的两种基本要素 .通过控制激光刻蚀区域 ,可控制薄膜表面形貌变化 ,从而实现可控的图案化设计 .1　实验部分1.1　原料及仪器　聚苯乙烯 (PS) :北京燕山石油化工…     

Room-temperature imprinting poly(acrylic acid)/poly(allylamine hydrochloride) multilayer films by using polymer molds

Layer-by-layer assembled polyelectrolyte multilayer films of poly(acrylic acid) (PAA)/poly(allylamine hydrochloride) (PAH) have been successfully patterned by room-temperature imprinting using a Norland Optical Adhesives (NOA 63) polymer mold. The proper amount of water in the PAA/PAH multilayer film can decrease the viscosity of the film and facilitate the imprinting. Many factors, such as imprinting pressure, length of imprinting time, and the structure and size of the patterns in the polymer mold, can produce an influence on the final imprinted pattern structures on multilayer films. A high imprinting pressure of 100 bar and elongated imprinting time of several hours is needed to achieve a patterned PAA/PAH multilayer film with a feature size of several tens of micrometers. With a twice imprinting, grid structures can be successfully produced when a NOA 63 mold having line structures is used. Room-temperature imprinting by using polymer NOA 63 mold provides a facile way to fabricate layered polymeric films with various kinds of pattern structures.     

Two-dimensional self-assembly of 1-pyrylphosphonic acid: transfer of stacks on structured surface

Strong hydrogen bonding and pi-pi stacking between 1-pyrylphosphonic acid (PYPA) molecules were exploited to create self-assembled two-dimensional supramolecular structures. Polycrystalline films of these laminate crystalline PYPA bilayers were easily deposited onto the solid supports through a simple spin-coating technique. Atomic force microscopy (AFM), scanning tunneling microscopy (STM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), UV-vis absorption, and fluorescence spectroscopy reveal that processing parameters, such as solvent, concentration, and surface of the substrate, are critical factors in determining the final morphology of the stacked film. Robust laminate structures could be obtained only when short alkyl chain protic solvents (methanol or ethanol) and a nonhydrophobic substrate surface were used. Polycrystalline films were formed through the nucleation and growth of PYPA molecules into laminate structures at the air/solvent interface before they land on the substrate during the spin-coating process. These films possess good mechanical properties and were easily transferred onto a SiO2/Si substrate that was patterned with Au electrodes without breaking their crystalline structures. The successful transfer of the laminate crystals allows us to probe their electrical properties through a field effect transistor device. A gating effect on the charge transport of the stacked films indicates that PYPA laminate crystal possesses p-typed semiconductor characteristics.     

Lithography for imprinting colored patterns with quantum dots

In this article, we report a new form of lithography that involves a reaction between a gas and an ion embedded in a polymer film. The principle is based on a combination of top-down and bottom-up approaches in which a transmission electron microscope grid is placed on a poly(vinylpyrrolidone) film containing Cd2+ ions, which is then exposed to H2S gas. This leads to the generation of a fluorescent yellow pattern due to the formation of CdS nanoparticles on exposed parts of the film. Also, we have used the same method to generate patterns in two colors by starting with a green fluorescent dye incorporated into the film and following the same procedure in which patterned yellow-orange CdS nanoaparticles are distributed over the background fluorescence of the dye. We have used fluorescence microscopy, UV-vis and fluorescence spectroscopy, transmission electron microscopy, atomic force microscopy, and X-ray diffraction methods for the characterization of the products and patterns. This method could possibly be a fairly general method of generating patterned materials on 2D and 3D substrates.     

微接触印刷技术在ITO基底上快速转移Au纳米粒子图案

采用无氰化学镀金法在聚二甲基硅氧烷(PDMS)印章表面镀金, 通过微接触印刷技术将PDMS印章上的Au 纳米粒子(AuNPs)分别转移到氧化铟锡(ITO)透明导电膜玻璃, 修饰了(3-巯基丙基)三甲氧基硅烷(MPTMS)的ITO基底(MPTMS/ITO)和表面电镀了铜膜的ITO(Cu/ITO)表面上, 同时形成有序的结构或者图案.通过场发射扫描电镜(FE-SEM), 原子力显微镜(AFM)和显微共聚焦激光拉曼光谱仪等对实验结果进行表征.结果表明, 该转移AuNPs的方法对基底表面特性并无特殊要求, 是一种简单、快速、无污染、低成本的AuNPs转移技术, 而且转移了AuNPs的ITO基底具有表面增强拉曼光谱(SERS)活性, 有望在SERS中有所应用.     

Patterned growth of oriented 2D covalent organic framework thin films on single-layer graphene

Two-dimensional covalent organic frameworks (COFs) are polymer networks that organize molecular building blocks into porous, layered structures of interest for organic optoelectronic and energy storage devices. Current synthetic methods produce these materials as either insoluble, microcrystalline powders or as oriented thin films on various substrates, including single-layer graphene (SLG). Under these conditions, COF thin films form on both the graphene-coated and bare regions of the substrate, suggesting uncontrolled nucleation processes that occur either in solution or nonselectively on different surfaces. Here, we describe modified polymerization conditions that provide COF films selectively on SLG. This finding enables COF films to be grown on lithographically patterned SLG substrates, which provide insight into the uniformity of film growth across the substrate and factors relevant to their nucleation and growth. The ability to grow COF films selectively on lithographically patterned SLG will facilitate their integration into devices. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 378–384     

基于粒子辅助水滴模板法制备仿生复眼结构的研究

将微粒“皮克林乳化效应”(Pickering emulsions)和水滴模板法(breath figure method)有机结合,探索通过建立粒子辅助的水滴模板法,实现纳米粒子在蜂窝状多孔膜内壁的自组装复合,构建微纳复合的多级仿生结构.并进一步利用聚二甲基硅氧烷(PDMS)复制转移技术,获得类似于复眼结构的多级微纳复合界面仿生结构.     

Patterning inorganic (CaCO3) thin films via a polymer-induced liquid-precursor process

The biomimetic synthesis of patterned mineral thin films, based on a combination of the microcontact printing technique and a novel crystallization process called the polymer-induced liquid-precursor (PILP) process, is demonstrated. The PILP process enables the deposition of smooth and continuous calcitic mineral films (up to 1500 nm in thickness) under low-temperature and aqueous-based processing conditions. The films are formed by deposition of colloidal droplets composed of a liquid-phase mineral precursor that is induced by a polymeric process-directing agent (polyaspartate or polyacrylate salts). The droplets can be preferentially deposited onto patterned substrates templated with self-assembled monolayers (SAMs) of alkanethiolate on gold. The droplets coalesce to form an amorphous mineral film, which then transforms (solidifies and crystallizes) while retaining the shape of the patterned template, providing a means for patterning the location and morphology of two-dimensional calcite crystals. A vertical substrate experiment supports the premise that the calcite films are created by adsorption of colloidal droplets from solution, rather than heterogeneous nucleation and growth of an amorphous phase on the SAMs. Large single-crystalline domains, on the order of 50-100 microm, can be "molded" into nonequilibrium morphologies by constraining the mineral precursor to a chemically defined "compartment". Biominerals are well recognized for their elaborate nonequilibrium molded crystal morphologies, and increasing evidence suggests that many biominerals are formed from an amorphous precursor that is stabilized by polyanionic proteins. The biomimetic system examined here, which consists of a polyanionic process-directing agent in combination with a functionalized organic template, offers a practical tool for generating complex inorganic structures such as those found in biominerals.     

Surface orientation of 3,4,5-tris-substituted benzoic acid amphiphiles

Regarding the molecular orientation on flat substrates, thin films have been studied of a series of wedge-shaped molecules (3,4,5-tris-substituted benzoate-benzo crown ether compounds) consisting of a hydrophobic outer rim and a polar group at the thin end which form columnar mesomorphic and crystalline structures. For most substrates studied here, autophobic dewetting is demonstrated to be caused by the formation of a monomolecular adlayer in which the molecules are oriented normal to the substrate surface with the hydrophobic tails directed away from the substrate. For thick films, this adlayer is shown to cause an "in-plane" orientation of the axis of the columnar state. An ordered in-plane oriented adlayer is observed only for highly ordered pyrolytic graphite as the substrate. In this case, specific interactions with the substrate cause formation of a well-ordered 2D pattern that might favor homeotropic orientation of the columnar structures but has to be optimized by further structural variation. The structure of the adsorbed monolayer is elucidated by combining contact angle measurements, plasmon resonance spectroscopy, and optical and scanning tunneling microscopy.     

Insight in the role of bovine serum albumin for promoting the in situ surface growth of polyhydroxybutyrate (PHB) on patterned surfaces via enzymatic surface-initiated polymerization

Polyhydroxyalkanoates (PHAs) are a family of aliphatic polyesters produced by a variety of microorganisms as a reserve of carbon and energy. Enzymes involved in the synthesis of PHAs can be utilized to produce polymers in vitro, both in bulk and on solid surfaces. Here, site-specific attachment of the key catalytic enzyme, PHA synthase, on lithographically patterned surfaces and subsequent addition of (R)-3-hydroxybutyryl-CoA substrate allowed us to fabricate spatially ordered polyhydroxybutyrate (PHB) polymeric structures via an in situ enzymatic surface-initiated polymerization (ESIP). By varying the reaction conditions, we enhanced the growth of PHB on solid surfaces and analyzed the resulting structures by fluorescence microscopy, atomic force microscopy (AFM), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and gel permeation chromatography (GPC). We found that stabilization of smaller PHB granule structures by an addition of bovine serum albumin (BSA) was the most important factor for a successful synthesis of a PHB layer up to 1mum in thickness, consisting mainly of larger cluster assemblies of PHB granules that cover the entire patterned area. Immunofluorescence detection and surface contact angle analysis revealed that BSA was physically bound to the PHB polymer all through the cluster, and reduced the overall hydrophobicity of the polymer surface. Based on information obtained from AFM, kinetic measurements and various polymer characterization methods, a plausible model for roles of BSA in the enhancement of PHB formation on surfaces is discussed. Furthermore, by using biotinylated BSA conjugates, we were able to incorporate biotin groups into the PHB polymer matrix, thus generating a bioactive surface that can be used for displaying other functional biomolecules through streptavidin-biotin interaction on the PHB structures. Because of its versatility, our fabrication strategy is expected to be a useful surface modification tool for numerous biomedical and biotechnological applications.     

Combining optical lithography with rapid microwave heating for the selective growth of Au/Ag bimetallic core/shell structures on patterned silicon wafers

We demonstrate a novel approach for the production of patterned films of nanometer-sized Au/Ag bimetallic core/shell nanoparticles (NPs) on silicon wafers. In this approach, we first self-assembled monodisperse Au NPs, through specific Au...NH(2) interactions, onto a silicon substrate whose surface had been modified with a pattern of 3-aminopropyltrimethoxysilane (APTMS) groups to form a sandwich structure having the form Au NPs/APTMS/SiO(2). These Au NPs then served as seeds for growing the Au/Ag bimetallic core/shell NPs: we reduced silver ions to Ag metal on the surface of Au seeds under rapid microwave heating in the presence of sodium citrate. Energy-dispersive X-ray analysis confirmed that the Au/Ag bimetallic core/shell NPs grew selectively on the regions of the surface of the silicon wafer that had been patterned with the Au seeds. Scanning electron microscopy images revealed that we could synthesize well-scattered, high-density (>82%) thin films of Au/Ag bimetallic core/shell NPs through the use of this novel strategy. The patterned structures that can be formed are simple to produce, easily controllable, and highly reproducible; we believe that this approach will be useful for further studies of nanodevices and their properties.     

Growth of Single‐Layered Two‐Dimensional Mesoporous Polymer/Carbon Films by Self‐Assembly of Monomicelles at the Interfaces of Various Substrates

Single‐layered two‐dimensional (2D) ultrathin mesoporous polymer/carbon films are grown by self‐assembly of monomicelles at the interfaces of various substrates, which is a general and common modification strategy. These unconventional 2D mesoporous films possess only a single layer of mesopores, while the size of the thin films can grow up to inch size in the plane. Free‐standing transparent mesoporous carbon ultrathin films, together with the ordered mesoporous structure on the substrates of different compositions (e.g. metal oxides, carbon) and morphologies (e.g. nanocubes, nanodiscs, flexible and patterned substrates) have been obtained. This strategy not only affords controllable hierarchical porous nanostructures, but also appends the easily modified and multifunctional properties of carbon to the primary substrate. By using this method, we have fabricated Fe₂O₃–mesoporous carbon photoelectrochemical biosensors, which show excellent sensitivity and selectivity for glutathione.     

Atmospheric-Pressure Plasma Reduction of Metal Cation-Containing Polymer Films to Produce Electrically Conductive Nanocomposites by an Electrodiffusion Mechanism

We describe an atmospheric-pressure plasma process for the reduction of metal cation-containing polymer films to form electrically conductive patterns. Thin films of poly(acrylic) acid (PAA) containing silver ions (Ag⁺) were prepared by mixing the polymer with silver nitrate (AgNO₃) in solution to produce a cross-linked precipitate, homogenizing, and depositing onto a substrate by doctor’s blade. Exposing the Ag–PAA films to a scanning microplasma resulted in reduction of the bulk dispersed Ag⁺ in a desired pattern at the film surface. The processed films were characterized by scanning electron microscopy, energy dispersive spectroscopy, thermogravimetric analysis, and current–voltage measurements. The resistances of the patterned features were found to depend on the thickness of the films, the microplasma scan rate, residual solvent in the film, and electric field created between the microplasma and the substrate. Together these results show that the formation of conductive features occurs via an electrodiffusion process where Ag⁺ diffuses from the film bulk to the surface to be reduced by the microplasma.