共查询到20条相似文献,搜索用时 15 毫秒
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Ion‐Specific Oil Repellency of Polyelectrolyte Multilayers in Water: Molecular Insights into the Hydrophilicity of Charged Surfaces 下载免费PDF全文
Dr. Xiaokong Liu Chuan Leng Li Yu Ke He Lauren Joan Brown Prof. Dr. Zhan Chen Prof. Dr. Jinhan Cho Prof. Dr. Dayang Wang 《Angewandte Chemie (International ed. in English)》2015,54(16):4851-4856
Surface wetting on polyelectrolyte multilayers (PEMs), prepared by alternating deposition of polydiallyldimethylammonium chloride (PDDA) and poly(styrene sulfonate) (PSS), was investigated mainly in water‐solid‐oil systems. The surface‐wetting behavior of as‐prepared PEMs was well correlated to the molecular structures of the uncompensated ionic groups on the PEMs as revealed by sum frequency generation vibrational and X‐ray photoelectron spectroscopies. The orientation change of the benzenesulfonate groups on the PSS‐capped surfaces causes poor water wetting in oil or air and negligible oil wetting in water, while the orientation change of the quaternized pyrrolidine rings on the PDDA‐capped surfaces hardly affects their wetting behavior. The underwater oil repellency of PSS‐capped PEMs was successfully harnessed to manufacture highly efficient filters for oil‐water separation at high flux. 相似文献
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Direct Formation of C−C Triple‐Bonded Structural Motifs by On‐Surface Dehalogenative Homocouplings of Tribromomethyl‐Substituted Arenes 下载免费PDF全文
Dr. Qiang Sun Xin Yu Meiling Bao Dr. Mengxi Liu Jinliang Pan Zeqi Zha Liangliang Cai Honghong Ma Dr. Chunxue Yuan Prof. Dr. Xiaohui Qiu Prof. Dr. Wei Xu 《Angewandte Chemie (International ed. in English)》2018,57(15):4035-4038
On‐surface synthesis shows significant potential in constructing novel nanostructures/nanomaterials, which has been intensely studied in recent years. The formation of acetylenic scaffolds provides an important route to the fabrication of emerging carbon nanostructures, including carbyne, graphyne, and graphdiyne, which feature chemically vulnerable sp‐hybridized carbon atoms. Herein, we designed and synthesized a tribromomethyl‐substituted compound. By using a combination of high‐resolution scanning tunneling microscopy, non‐contact atomic force microscopy, and density functional theory calculations, we demonstrated that it is feasible to convert these compounds directly into C?C triple‐bonded structural motifs by on‐surface dehalogenative homocoupling reactions. Concurrently, sp3‐hybridized carbon atoms are converted into sp‐hybridized ones, that is, an alkyl group is transformed into an alkynyl moiety. Moreover, we achieved the formation of dimer structures, one‐dimensional molecular wires, and two‐dimensional molecular networks on Au(111) surfaces, which should inspire further studies towards two‐dimensional graphyne structures. 相似文献
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Chao Gao 《Macromolecular rapid communications》2006,27(11):841-847
Summary: Supramolecular self‐assembly of poly(methyl methacrylate)‐grafted multiwalled carbon nanotubes (MWNT‐g‐PMMA) was reported herein. The MWNT‐g‐PMMA (85 wt.‐% PMMA) dispersed in tetrahydrofuran could self‐assemble into suprastructures on surfaces such as gold, mica, silicon, quartz, or carbon films. With decreasing concentration of the MWNT‐g‐PMMA from 3 to 0.1 mg · mL−1, the assembled structures changed from cellular and basketwork‐like forms to multilayer cellular networks and individual needles. SEM, AFM, and TEM measurements confirmed the morphology of the assembled suprastructures, and revealed the assembly mechanism. Phase separation during evaporation of the solvent drives the MWNT‐g‐PMMA nanohybrids to assemble and form the suprastructures, and the rigid MWNTs stabilize the structures.
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Rafal Zuzak Dr. Ruth Dorel Dr. Marek Kolmer Prof. Marek Szymonski Dr. Szymon Godlewski Prof. Antonio M. Echavarren 《Angewandte Chemie (International ed. in English)》2018,57(33):10500-10505
A unified approach to the synthesis of the series of higher acenes up to previously unreported undecacene has been developed through the on‐surface dehydrogenation of partially saturated precursors. These molecules could be converted into the parent acenes by both atomic manipulation with the tip of a scanning tunneling and atomic force microscope (STM/AFM) as well as by on‐surface annealing. The structure of the generated acenes has been visualized by high‐resolution non‐contact AFM imaging and the evolution of the transport gap with the increase of the number of fused benzene rings has been determined on the basis of scanning tunneling spectroscopy (STS) measurements. 相似文献
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Jagoba Jon Iturri Ramos Irantzu Llarena Luis Fernndez Sergio Enrique Moya Edwin Donath 《Macromolecular rapid communications》2009,30(20):1756-1761
The quartz crystal microbalance with dissipation technique (QCM‐D) and atomic force microscopy (AFM) have been employed to study the interaction of N‐tetradecyl trimethyl ammonium bromide (TdTmAB) with polyelectrolyte multilayers containing poly(sodium 4‐styrene sulfonate) (PSS) as the polyanion and either poly(allylamine hydrochloride) (PAH) or poly(diallyl dimethyl ammonium chloride) (PDADMAC) as the polycations. The multilayers were exposed to aqueous solutions of TdTmAB. This resulted in a selective removal of PDADMAC PSS layers while layers with PAH as polycation remained stable. It is suggested that PDADMAC/PSS multilayers can be employed as strippable protecting layers.
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Dr. Takashi Nishiyama Prof. Koji Takahashi Tatsuya Ikuta Dr. Yutaka Yamada Prof. Yasuyuki Takata 《Chemphyschem》2016,17(10):1500-1504
Highly stable nanoscale gas states at solid/liquid interfaces, referred to as nanobubbles, have been widely studied for over a decade. In this study, nanobubbles generated on a hydrophobic Teflon amorphous fluoroplastic thin film in the presence and absence of hydrophilic carbon domains are investigated by peak force quantitative nanomechanics. On the hydrophobic surface without hydrophilic domains, a small number of nanobubbles are generated and then rapidly decrease in size. On the hydrophobic surface with hydrophilic domains, the hydrophilic domains have a significant effect on the generation and stability of nanobubbles, with bubbles remaining on the surface for up to three days. 相似文献
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Stimuli‐Responsive Hybrid Coatings of Polyelectrolyte Multilayers and Nano‐Patterned Polymer Brushes
Sung Yun Yang Dul‐Yi Kim Sang‐Mi Jeong Ji‐Woong Park 《Macromolecular rapid communications》2008,29(9):729-736
A new type of polymeric hybrid coating is created by layer‐by‐layer deposition of polyelectrolyte multilayers (PEM) onto nano‐patterned polymer brushes (NPB). The PEM is a hydrogen‐bonded multilayer consisting of poly(acrylic acid) and poly(acrylamide) and the NPB is derived from a surface reactive rod‐coil block copolymer, polystyrene‐block‐poly[3‐(triethoxysilyl)propylisocyanate]. The thickness of the PEM coating is optimized with respect to the height of the NPB mounds, to yield PEM/NPB hybrid coatings with unique nano‐embossed or nano‐porous structures that can be interchangeable by heating and moisture annealing. The hybrid coating is patternable by the micro‐contact printing method. The results demonstrate that the combination of surface‐bound, hydrophobic NPB layer with hydrophilic PEM films at the nanoscopic level offers a new organic hybrid coating with novel surface properties.
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Dr. Charles Esnault Prof. Benoît Chénais Dr. Nathalie Casse Dr. Nicolas Delorme Prof. Guy Louarn Prof. Jean‐François Pilard 《Chemphyschem》2013,14(2):338-345
Carbon and chromium surfaces were modified by electrochemical reduction of a diazonium salt formed in situ from the sulfanilic acid. The organic layer formed was activated by phosphorus pentachloride (PCl5) to form a benzene sulfonil chloride (Ar? SO2Cl). An electrochemical study of the blocking effect and the activity of this surface was carried out on a carbon electrode. The chromium surface study was completed by X‐ray photoelectron spectroscopy and atomic force microscopy to characterize the formation of a compact monolayer (0.8 nm height and roughness 0.2–0.3 nm). The compactness and the activity of this organic monolayer allowed us to affix a length dsDNA with the aim of analyzing the formation of a complex between dsDNA and a protein. The interaction of a transposase protein with its target dsDNA was investigated. The direct imaging of the nucleoproteic complex considered herein gives new insights in the comprehension of transposase–DNA interaction in agreement with biochemical data. 相似文献
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Dr. Shenglin Jin Dr. Jie Liu Dr. Jianyong Lv Shuwang Wu Prof.?Dr. Jianjun Wang 《化学:亚洲杂志》2018,13(11):1406-1414
The design and fabrication of interfacial materials for anti‐icing is of great importance, since undesired ice accumulation leads to serious economic, energy, and safety issues. Substantial progress on interfacial materials for the passive removal of ice has been achieved in the past three years. The present focus review critically summarizes and analyzes recent breakthroughs in interfacial materials for anti‐icing. In particular, we focus on the effect of surface textures on the timely removal of water droplets, the microscopic mechanism of ice formation, and the effect of an interfacial layer's properties on easy shedding of formed ice with a view towards designing high‐performance and durable interfacial materials for anti‐icing beyond superhydrophobic materials. 相似文献
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Spatial and Directional Control over Self‐Assembly Using Catalytic Micropatterned Surfaces 下载免费PDF全文
Dr. Alexandre G. L. Olive Nor Hakimin Abdullah Dr. Iwona Ziemecka Dr. Eduardo Mendes Dr. Rienk Eelkema Prof. Dr. Jan H. van Esch 《Angewandte Chemie (International ed. in English)》2014,53(16):4132-4136
Catalyst‐assisted self‐assembly is widespread in nature to achieve spatial control over structure formation. Reported herein is the formation of hydrogel micropatterns on catalytic surfaces. Gelator precursors react on catalytic sites to form building blocks which can self‐assemble into nanofibers. The resulting structures preferentially grow where the catalyst is present. Not only is a first level of organization, allowing the construction of hydrogel micropatterns, achieved but a second level of organization is observed among fibers. Indeed, fibers grow with their main axis perpendicular to the substrate. This feature is directly linked to a unique mechanism of fiber formation for a synthetic system. Building blocks are added to fibers in a confined space at the solid–liquid interface. 相似文献
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Francesca Mirabella Eman Zaki Dr. Francisco Ivars‐Barceló Xiaoke Li Joachim Paier Joachim Sauer Shamil Shaikhutdinov Hans‐Joachim Freund 《Angewandte Chemie (International ed. in English)》2018,57(5):1409-1413
The initial stages of water adsorption on magnetite Fe3O4(111) surface and the atomic structure of the water/oxide interface remain controversial. Herein, we provide experimental results obtained by infrared reflection–absorption spectroscopy (IRAS) and temperature‐programmed desorption (TPD), corroborated by density functional theory (DFT) calculations showing that water readily dissociates on Fetet sites to form two hydroxo species. These act as an anchor for water molecules to form a dimer complex which self‐assembles into an ordered (2×2) structure. Water ad‐layer ordering is rationalized in terms of a cooperative effect induced by a hydrogen‐bonding network. 相似文献
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Dr. Shu Huang Prof. Dayang Wang 《Angewandte Chemie (International ed. in English)》2017,56(31):9053-9057
Coating solid surfaces with cellulose nanofibril (CNF) monolayers via physical deposition was found to keep the surfaces free of a variety of oils, ranging from viscous engine oil to polar n-butanol, upon water action. The self-cleaning function was well correlated with the unique molecular structure of the CNF, in which abundant surface carboxyl and hydroxy groups are uniformly, densely, and symmetrically arranged to form a polar corona on a crystalline nanocellulose strand. This isotropic core–corona configuration offers new and easily adoptable guidance to design self-cleaning surfaces at the molecular level. Thanks to its excellent self-cleaning behavior, the CNF coating converted conventional meshes into highly effective membranes for oil–water separation with no prior surface treatment required. 相似文献
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Yael Pascal‐Levy Evgeny Shifman Dr. Manish Pal‐Chowdhury Eitan M. Hajaj Oleg Shtempluck Alexey Razin Valeri Kochetkov Prof. Yuval E. Yaish 《Chemphyschem》2012,13(18):4202-4206
Humidity plays an important role in molecular electronics. It facilitates charge movement on top of dielectric layers and modifies the device transfer characteristics. Using two different methods to probe temporal charge redistribution on the surface of dielectrics, we were able to extract the surface humidity for the first time. The first method is based on the relaxation time constants of the current through carbon nanotube field‐effect transistors (CNTFETs), and the second is based on electric force microscopy (EFM) measurements. Moreover, we found that applying external gate biases modifies the surface humidity. A theoretical model based on dielectrophoretic attraction between the water molecules and the substrate is introduced to explain this observation, and the results support our hypothesis. Furthermore, it is found that upon the adsorption of two to three layers of water the surface conductivity saturates. 相似文献