Cover Picture: Fabrication and Characterization of Three‐Dimensional Silver‐Coated Polymeric Microstructures (Adv. Funct. Mater. 13/2006)

Kuebler and co‐workers report on p. 1739 a method for preparing conductive and optically reflective silver‐coated polymeric microstructures having virtually any 3D form. Shown are reflection images of a silvered five‐layer simple‐cubic lattice having a period of 2.4 μm (background) and a macroscopic silvered polymer film (inset). To prepare metallopolymeric microstructures, 3D polymeric scaffolds are first created by multiphoton direct laser writing, then functionalized with gold particles, and metallized using nucleated electroless silver deposition. A method is reported for fabricating complex 3D silver‐coated polymeric microstructures. The approach is based on the creation of a crosslinked polymeric microscaffold via patterned multiphoton‐initiated polymerization followed by surface‐nucleated electroless deposition of silver. The conductivity and reflectivity of the resulting silver–polymer composites and the nanoscale morphology of the deposited silver are characterized. Sub‐micrometer thick layers of silver can be controllably deposited onto surfaces, including those of 3D microporous forms without occluding the interior of the structure. The approach is general for silver coating crosslinked polymeric structures based on acrylate, methacrylate, and epoxide resins and provides a new path to complex 3D micrometer‐scale devices with electronic, photonic, and electromechanical function.     

High-Resolution Patterned Functionalization of Slippery “Liquid-Like” Brush Surfaces via Microdroplet-Confined Growth of Multifunctional Polydopamine Arrays

Slippery omniphobic covalently attached liquids enable smooth, transparent, pressure- and temperature-resistant, and liquid-repellent coatings. Patterned functionalization of such surfaces would drive technology developments and fundamental understandings in broad applications from biosensors to sustainable smart surfaces. Herein an additive microcontact printing approach in combination with the microdroplet-confined synthesis is developed to functionalize slippery surfaces tethered with “liquid-like” linear poly(dimethylsiloxane) by multifunctional polydopamine (PDA) arrays. Using glycerol and non-ionic surfactant Tween-20, microdroplet arrays containing dopamine monomers are printed onto the slippery surfaces and serve as microreactors for the in situ growth of PDA micropatterns. The confined growth approach enables tunable feature size, height, and morphology of the patterns, through which sub-micrometer PDA dot arrays over centimeter-square patterning area can be reliably achieved. Furthermore, the reactive and hydrophilic PDA micropatches allow further functionalization of the slippery surfaces with a diverse variety of materials, meanwhile the anti-fouling and dynamically dewetting “liquid-like” brushes permit minimum background contamination. Proof-of-concept demonstrations include PDA-initiated photografting for stimuli-responsive polymer functionalization, protein immobilization for microarray-based immunoassays, as well as sliding-induced selective dewetting of organic solutions to pattern photoluminescent perovskite microcrystals and nanoparticles. The current approach illustrates the potential for applying patterned slippery surfaces with multifunctional architectures in many fields.     

Direct Photomodification of Polymer Surfaces: Unleashing the Potential of Aryl‐Azide Copolymers

The possibility to impart surface properties to any polymeric substrate using a fast, reproducible, and industrially friendly procedure, without the need for surface pretreatment, is highly sought after. This is in particular true in the frame of antibacterial surfaces to hinder the threat of biofilm formation. In this study, the potential of aryl‐azide polymers for photofunctionalization and the importance of the polymer structure for an efficient grafting are demonstrated. The strategy is illustrated with a UV‐reactive hydrophilic poly(2‐oxazoline) based copolymer, which can be photografted onto any polymer substrate that contains carbon–hydrogen bonds to introduce antifouling properties. Through detailed characterization it is demonstrated that the controlled spatial distribution of the UV‐reactive aryl‐azide moieties within the poly(2‐oxazline) structure, in the form of pseudogradient copolymers, ensures higher grafting efficacy than other copolymer structures including block copolymers. Furthermore, it is found that the photografting results in a covalently bound layer, which is thermally stable and causes a significant antiadherence effect and biofilm reduction against Escherichia coli and Staphylococcus epidermidis strains while remaining noncytotoxic against mouse fibroblasts.     

Surface Plasmons and Visible Light Iniferter Initiated Polymerization for Nanolocal Functionalization of Mesoporous Separation Layers

Although the technological relevance of mesoporous ceramic polymer hybrid materials is well accepted, missing functionalization concepts enabling 3D nanoscale local control of polymer placement into mesoporous materials, including thin films, and ideally using controlled polymerization techniques limit the application potential. Here, nanolocal functionalization of mesoporous separation layers using controlled, visible light iniferter initiated polymerization allowing responsive polymer functionalization locally limited to the irradiated spot is introduced. Thereby, two visible light sensitive iniferters, s-p-trimethoxysilylbenzyl-S´-dodecyltrithiocarbonate and 4-cyano-4-((dodecylsulfanylthiocarbonyl)sulfanyl)pentanoic acid, are developed for polymer functionalization of mesoporous films in a grafting from and a grafting through approach. 3D nanolocal polymer placement close to the proximity of the plasmonic field source is demonstrated by combining these visible light iniferter initiated polymerizations with optical near field modes, such as localized surface plasmon resonance (LSPR). As the location of the LSPR in mesoporous films can be controlled by placing metal alloy nanoparticles into these films and film thicknesses can be adjusted, this strategy is applied for precise positioning of polymers into mesoporous films with nanolocal control in three dimensions and thus reduces the gap in precision of functional group positioning between technological and biological nanopores.     

Surface Functionalization of Thermoplastic Polymers for the Fabrication of Microfluidic Devices by Photoinitiated Grafting

Photografting has been used for the surface modification of a wide range of commercial commodity polymers such as poly‐ styrene, poly(methyl methacrylate), poly(dimethyl siloxane), polycarbonate, Parylene C, polypropylene, cyclic olefin copolymer, and hydrogenated polystyrene that are useful substrate materials for the fabrication of microfluidic chips. Since the chain propagation is initiated after UV light‐activated abstraction of a hydrogen atom from the surface of channels within the materials, their permeability for UV light was tested and polyolefins were found to be the best candidates. A number of monomers with a variety of functional groups such as perfluorinated, hydrophobic, hydrophilic, reactive, acidic, basic, and zwitterionic have been successfully grafted from the surface of selected substrates, and the grafting efficiency determined using X‐ray photoemission spectroscopy. Layered surface structures were prepared by consecutive grafting of different monomers. Our approach also enables photolithographic patterning of surfaces and specific functionalization of confined areas within the microchannel.     

Fabrication and Characterization of Three‐Dimensional Silver‐Coated Polymeric Microstructures

A method is reported for fabricating complex 3D silver‐coated polymeric microstructures. The approach is based on the creation of a crosslinked polymeric microscaffold via patterned multiphoton‐initiated polymerization followed by surface‐nucleated electroless deposition of silver. The conductivity and reflectivity of the resulting silver–polymer composites and the nanoscale morphology of the deposited silver are characterized. Sub‐micrometer thick layers of silver can be controllably deposited onto surfaces, including those of 3D microporous forms without occluding the interior of the structure. The approach is general for silver coating crosslinked polymeric structures based on acrylate, methacrylate, and epoxide resins and provides a new path to complex 3D micrometer‐scale devices with electronic, photonic, and electromechanical function.     

Cell Adhesion and Cellular Patterning on a Self‐Assembled Monolayer of Zeolite L Crystals

Chemically functionalized self‐assembled monolayers made by disk‐shaped zeolite L nanocrystals are used as models for biocompatible surfaces to study cell‐adhesion behavior. Different chemical groups lead to different cellular behavior and fluorescent‐molecule‐loaded zeolites allow the position of the cells to be determined. Furthermore, a patterned monolayer of asymmetrically functionalized zeolite L obtained by microcontact chemistry is used to grow cells. A spatial recognition of the cells, which proliferate only on the bioactive‐molecule‐functionalized stripes, is possible.     

Implementing Thermometry on Silicon Surfaces Functionalized by Lanthanide‐Doped Self‐Assembled Polymer Monolayers

The thermal gradients generated at submicrometer scale by the millions of transistors contained in integrated circuits are becoming the key limiting factor for device integration in micro‐ and nanoelectronics. Noncontact thermometric techniques with high‐spatial resolution are, thus, essential for noninvasive off‐chip characterization and heat management on Si surfaces. Here, the first ratiometric luminescent molecular thermometer implemented in a self‐assembled polymer monolayer functionalized Si surface is reported. The functionalization of Si surfaces with luminescent thermometers constitutes a proof‐of‐concept that foretells a wide range of applications in Si‐based micro‐ and nanostructures. The thermometric functionalization of the Si surface with Tb³⁺ and Eu³⁺ complexes leads to a thermal sensitivity up to 1.43% K^?1, a cycle–recycle reliability of 98.6%, and a temperature uncertainty of less than 0.3 K. The functionalized surface presents reversible bistability that can be used as an optically active molecular demultiplexer.     

CH3I在532nm及455.5nm激光作用下多光子电离研究

本文利用飞行时间质谱仪研究了532nm和455.5nm激光作用下CH3I分子的多光子电离解离（MPID）。在532nm激光作用下，CH3I分子由双光子激发到A带的A2态，它的MPID属母体离子阶梯模式;在455.5nm激光作用下，CH3I分子由双光子激发到A带的3E态，它的MPID属中性碎片光电离模式。     

激光强度的时间和空间分布对多光子过程的影响

在激光强度接近实际的时间和空间分布下,计算了三能级系统（１＋１）多光子过程电离效率和光强指数随激光能量的变化关系。并将各种分布情况下的计算结果与采用方波近似得到的结果进行了比较,得到了激光强度的时间和空间分布对多光子过程的影响。实验也证实了模拟计算结果的正确性。     

266nm激光作用下1,3-二溴苯的多光子电离和解离研究

在波长为266 nm的激光作用下对1,3-二溴苯分子的多光子电离解离过程进行了研究,获得了溴苯分子的MPIF-TOF质谱,并测得了各碎片离子占总离子信号的百分比对激光强度的依赖关系.用这些实验结果分析1,2-二溴苯分子的多光子电离解离机理,得出1,3-二溴苯的MPI过程主要是母体分子解离-中性碎片电离C6H 4,C5H 3,C4H 2,C3H 等碎片离子主要是经过离子离解阶梯模式产生的,并给出了可能的解离通道.     

A Three‐Dimensional Gold‐Decorated Nanoporous Copper Core–Shell Composite for Electrocatalysis and Nonenzymatic Biosensing

Bimetallic core–shell nanostructures have attracted increasing attention due to their low material costs along with enhanced chemico‐physical properties in comparison with their monometallic counterparts. Here, a novel gold‐decorated nanoporous copper (Au@NPC) core–shell composite fabricated by a facile in situ hydrometallurgy approach is reported. Thin gold shells with a controllable thickness are homogeneously deposited onto the internal surfaces of 3D nanoporous copper via a spontaneous displacement reaction while nanoporous copper is utilized as a reduction agent as well as 3D template and substrate. The resulting inexpensive core–shell nanostructure exhibits significant electrocatalytic activity for the oxidation of methanol and high non‐enzymatic sensitivity in detecting glucose.     

Nanopatterning of Anionic Nanoparticles based on Magnetic Prussian‐Blue Analogues

Prussian‐blue analogues (PBA) are a family of molecule‐based magnetic compounds of general formula A_xM_y[M’(CN)₆]_z, whose magnetic properties can be tuned by an external stimulus. This tunability makes PBA good candidates for their integration into new electronic or spintronic devices. As a previous step to accomplish this integration, PBA need to be deposited onto surfaces in controllable ways and if possible into specific positions on the surface. Even though the study of PBA has traditionally been limited to bulk, lately they have also been processed as nanoparticles (NPs). Here an efficient approach is presented for the accurate deposition and organization of PBA‐NPs of different sizes (from ～6 to ～25 nm) over silicon surfaces. The approach used in this work, relies on a combination of surface functionalization with local oxidation nanolithography (LON) and uses electrostatic interactions between PBA‐NPs and a charged self‐assembled monolayer patterned on specific parts of the silicon surface. By using atomic force microscopy (AFM), magnetometry, infrared spectroscopy (IR) and auger electron spectroscopy (AES) we show that the deposition process does not affect NPs properties. In addition, we present a study on the evolution of AFM nanolithographed SiO₂ patterns under sonication.     

Polymer‐Modified Mesoporous Silica Thin Films for Redox‐Mediated Selective Membrane Gating

Controlling structure and function to switch ionic transport through synthetic membranes is a major challenge in the fabrication of functional nanodevices. Here we describe the combination of mesoporous silica thin films as structural unit, functionalized with two different redox‐responsive ferrocene‐containing polymers, polyvinylferrocene (PVFc) and poly(2‐(methacryloyloxy)ethyl ferrocenecarboxylate) (PFcMA), by using either a grafting to, or a grafting from approach. Both mesoporous film functionalization strategies are investigated in terms of polymer effect on ionic permselectivity. A significantly different ionic permselective behavior can be observed. This is attributed to different polymer location within the mesoporous film, depending on the functionalization strategies used. Additionally, the influence of chemical oxidation on the ionic permselective behavior is studied by cyclic voltammetry showing a redox‐controlled membrane gating as function of polymer location and the pH value. This study is a first step of combining redox‐responsive ferrocene‐containing polymers and mesoporous membranes, and thus towards redox‐controlled ionic transport through nanopores.     

Direct Surface Patterning from Solutions: Localized Microchemistry Using a Focused Laser

A method for creating microscale‐patterned surfaces by direct‐write lithography is described. A tightly focused, low‐power infrared laser beam is applied to a homogeneous precursor solution containing soluble reagents. When the laser is focused directly at a glass–solution interface, it initiates the local precipitation of a solid product that attaches firmly to the substrate. Operating the laser momentarily forms isolated spots, whereas moving the microscope stage or the laser spot draws continuous lines. The method has been demonstrated for metallic silver and gold, for oxidized copper, and for molybdenum disulfide, suggesting a broad range of suitable materials. Silver patterns were further modified by chemical reactions. Their morphology and physical properties can be altered during deposition by the use of capping agents, which may provide an onset for further functionalization.     

High‐Resolution Patterning of Hydrogels in Three Dimensions using Direct‐Write Photofabrication for Cell Guidance

The development of three‐dimensional, spatially defined neuronal cultures that mimic chemical and physical attributes of native tissue is of considerable interest for various applications, including the development of tailored neuronal networks and clinical repair of damaged nerves. Here, the use of multiphoton excitation to photocrosslink protein microstructures within three‐dimensional, optically transparent hydrogel materials, such as those based on hyaluronic acid, is reported. Multiphoton excitation confines photocrosslinking to a three‐dimensional voxel with submicron spatial resolution, enabling fabrication of protein matrices with low‐ to sub‐micrometer feature sizes by scanning the focus of a laser relative to the reagent solution. These methods can be used to create complex three‐dimensional architectures that provide both chemical and topographical cues for cell culture and guidance, providing for the first time a means to direct cell adhesion and migration on size scales relevant to in vivo environments. Using this approach, guidance of both dorsal root ganglion cells (DRGs) and hippocampal neural progenitor cells (NPCs) along arbitrary, three‐dimensional paths is demonstrated.     

Quantification of Grafting Densities Achieved via Modular “Grafting‐to” Approaches onto Divinylbenzene Microspheres

The surface modification of divinylbenzene (DVB)‐based microspheres is performed via a combination of reversible addition fragmentation chain transfer (RAFT) polymerization and rapid hetero‐Diels–Alder (HDA) chemistry with the aim of quantifying the grafting densities achieved using this “grafting‐to” method. Two variants of the RAFT‐HDA concept are employed to achieve the functionalization of the microspheres. In the first approach, the microspheres are functionalized with a highly reactive diene, i.e., cyclopentadiene, and are subsequently reacted with polystyrene chains (number‐averaged molecular weight, M_n = 4200 g mol^?1; polydispersity index, PDI = 1.12.) that carry a thiocarbonyl moiety functioning as a dienophile. The functionalization of the microspheres is achieved rapidly under ambient conditions, without the aid of an external catalyst. The surface grafting densities obtained are close to 1.2 × 10²⁰ chains per gram of microspheres. In the second approach, the functionalization proceeds via the double bonds inherently available on the microspheres, which are reacted with poly(isobornyl acrylate) chains carrying a highly dienophilic thiocarbonyl functionality; two molecular weights (M_n = 6000 g mol^?1, PDI = 1.25; M_n = 26 000 g mol^?1, PDI = 1.26) are used. Due to the less reactive nature of the dienes in the second approach, functionalization is carried out at elevated temperatures (T = 60 °C) yet in the absence of a catalyst. In this case the surface grafting density is close to 7 chains nm^?2 for M_n = 6000 g mol^?1 and 4 chains nm^?2 for M_n = 26 000 g mol^?1, or 2.82 × 10¹⁹ and 1.38 × 10¹⁹ chains g^?1, respectively. The characterization of the microspheres at various functionalization stages is performed via elemental analysis for the quantification of the grafting densities and attenuated total reflectance (ATR) IR spectroscopy as well as confocal microscopy for the analysis of the surface chemistry.     

Si(CH_3)_4分子的多光子电离和解离研究

对Si(CH_3)_4分子在280.0nm波长的激光多光电子电离和解高产物离子的飞行时间质谱进行了测定,结果表明:Si(CH_3)_4分子解离和电离后的主要正离子产物为:Si(CH_3)_2~+、Si~+和CH_x~+(x=0,1,2,3)离子等。本文还讨论了不同激光功率下Si(CH_3)_4分子产生不同碎片产物离子的机理。     

醇/水混合团簇的多光子电离质谱及从头算研究

利用多光子电离技术和飞行时间质谱仪实验研究了醇/水混合团簇的光电离质谱。在脉冲激光波长为355nm条件下,观测到以质子化(ROH)n(H2O)H+ 混合团簇离子和(ROH)nH+团簇离子为主的电离产物。醇水混合团簇电离后团簇离子发生内部质子化转移反应是形成质子化团簇离子的主要原因。应用量化计算,构造了质量数较小的几个团簇离子的可能的空间几何构型,发现二元团簇离子(CH3OH)n(H2O)H+是以(CH3OH)H+作为内核离子,再通过氢键与其它分子组合而构成团簇离子。