Papers by Keyword: Langmuir-Blodgett Film

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Authors: C.E. Tucker, F.A. Smith, Paul G. Coleman
Authors: C.B. McArdle, S.J. Harris, J. Guthrie, V. Casey
Authors: András Deák, Erzsébet Hild, Attila L. Kovács, Zoltán Hórvölgyi
Abstract: Nanostructured Langmuir-Blodgett (LB) films of Stöber-silica nanoparticles have been prepared on silicon and quartz glass substrates. The deposited layers were investigated using scanning angle reflectometry and UV-Vis spectroscopy. The reflectivity and the transmittance spectra of the LB films were evaluated using a model based on thin layer optics. Film thickness and effective refractive index of the films were determined. From the refractive index values the volume fraction of the particles in the film was estimated by effective medium approach.
Authors: Ti Feng Jiao, Jing Xin Zhou
Abstract: In order to investigate the chiral interfacial assembly of special amphiphile, a trigonal Schiff base compound with long alkyl chains was designed and synthesized, and its supramolecular assembly and interaction properties were investigated by spectral and morphological measurements. Condensed monolayers were obtained on pure water surface, in which flat and uniform domains were obtained for the monolayers. When an anionic tetrakis(4-sulfonatonphenyl)porphine (TPPS) was added into an acidic subphase, an in situ complex formation between the trigonal amphiphile and TPPS occurred. The complex monolayers were transferred onto solid substrate and TPPS existed as J-aggregate and J-aggregate in the complex films. Due to the multisited positive charges in the spacer on acidic subphase, the complex films of trigonal amphiphile with TPPS appeared as short nanorod structures and formed two-dimensional (2D) conglomerate chiral domains.
Authors: T. Niwa, Masayoshi Tanaka, Takatoshi Kinoshita
Abstract: In order to construct an intelligent functional nano-interface, the self-organized structure of Langmuir-Blodgett (LB) film was investigated by atomic force microscopy (AFM). As a building block, a monodisperse loop-helix-helix triblock copolypeptide containing the helix of which hydrophobic L-leucine residues align on a single face, “leucine zipper”, was synthesized by recombinant DNA techniques with a designed amino acid sequence. AFM observation on the surface structure of LB films constructed at surface pressures of 2, 5 and 18 mN/m revealed that structural transition from ring- or disk-like aggregations to a lane-like fabrication occurred with compression of the copolypeptide membrane on the water of pH 4. The leucine zipper in the copolypeptide was suggested to perform as an important basis for nanostructure formation through a hydrophobic interaction. Exploitation of the recognition and specific binding sites in the copolypeptide will allow the self-assembling mechanism of the copolypeptide to be developed to a novel nano-template.
Authors: R. Rella, P. Siciliano, A. Tepore, L. Valli, G. Vasapollo
Authors: Sara Cavaliere, Frédéric Raynal, Arnaud Etcheberry, Michel Herlem, Henri Perez
Abstract: 4-mercaptoaniline functionalised platinum particles of 2 nm diameter were synthesised and over-grafted with 2-thiophenecarbonyl chloride. The derivative particles were dispersed in DMSO and gave long term stable suspensions. The Langmuir-Blodgett technique was then used to build up stable Langmuir-Blodgett films and the electrochemical behaviour of these ultra-thin films towards oxygen reduction was investigated in an acidic medium. It revealed direct activity without any previous activation treatments despite of the presence of the organic shell at the particle surface. Furthermore, XPS experiments revealed that the organic crown was not significantly destroyed on prolonged cycling. The results open a way to study original and versatile platinum-based nanocomposites.
Authors: F. Al-Taher, J. Telegdi, Erika Kálmán
Abstract: Langmuir-Blodgett films (LB) of hydroxamic amphiphiles were used as coating barriers on metal surface against corrosion. Two long-chain hydroxamic acids [CH3(CH2)16CONHOH] monolayers in the presence of some divalent cations (Ca2+, Mg2+, and Cu2+) have been studied at different pH of the subphase. The monolayer was characterized by surface pressure-area isotherms and visualized by Brewster angle microscope (BAM). Compact Langmuir layers were deposited on copper surface, where the modified surfaces were characterized by contact angle measurement as well as by electrochemical techniques. The morphology of LB coated copper surface was visualized by atomic force microscopy (AFM). The coated copper surfaces were tested in corrosive media at acidic and neutral pH. The results show that the multi-molecular LB films of hydroxamic acid salts form good barriers against copper corrosion. The comparison of these results with copper coated by LB layers without divalent cations shows that the presence of divalent cations in the subphase increases the copper corrosion inhibition. The octadecanoyl hydroxamic acid (C18N) results in better and more stable monolayer with cations in the subphase.
Authors: Jing Xin Zhou, Ti Feng Jiao, Adan Li, Xu Hui Li, Xu Duo Bai
Abstract: A series of Schiff bases derivatives with aromatic spacer have been designed and their interfacial phase behaviors and coordination with Cu(II) ions were investigated. It has been found that on the subphase containing Cu(II) ions, all of the Schiff bases can coordinate with Cu(II) in situ in the spreading films, especially for NSB-C16 with the obvious conformational change of alkyl chains. The in situ Cu(II)-coordinated films could be transferred onto solid substrates and subsequently characterized by various spectroscopic methods such as UV-vis and Fourier transform infrared spectra as well as the morphological characterization with atomic force microscopy measurement. Depending on the different groups, these amphiphiles showed different aggregation behaviors in the Langmuir-Blodgett films.
Authors: Feng Yan Wang, Ti Feng Jiao, Qing Rui Zhang
Abstract: Gemini amphiphiles have been widely investigated in many aspects due to the unique structure. In this study, two gemini-type Schiff base amphiphiles containing aromatic spacers were synthesized and characterized in Langmuir-Blodgett films. Both compounds formed stable multilayer films and showed distinct phase behaviours on water surface and ion subphase. When the compounds spread on Cu (II) ions subphase, an in-situ coordination occurred for both ligands. While spectral measurements confirmed the coordination with Cu (II) ions and aggregation mode, the morphological investigations showed the distinct nanostructures and molecular rearrangement depended on the molecular spacers and aggregation modes. For both process, the aromatic spacers in gemini amphiphiles have predominant effect in regulating the aggregation modes and spectral changes in organized molecular films.
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