Papers by Keyword: Self-Assembly

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Authors: Ning Jie Guo, Hui Ling Tai, Zong Biao Ye, Guang Zhong Xie
Abstract: In this paper, the graphene-polyaniline (PANI) nanocomposite thin film was prepared by the in situ self-assembly method for the ammonia (NH3) gas sensor application, which was characterized by scanning electron microscopy (SEM) and UV-vis spectroscopy. The NH3 sensing performance and mechanism of the nanocomposite film were investigated. The results revealed that the sensor based on graphene-polyaniline nanocomposite film exhibited better sensing properties and restorability than those of single graphene film.
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Authors: Yu Mei Gong, Ying Xin He, Jing Guo, Hong Zhang
Abstract: This study developed a concise route to fabricate TiO2 nanoporous and nanopillar films based on the self-assembly of block-copolymer thin films in periodic nanostructures. We obtained the perpendicularly oriented cylindrical domains in polystyrene-b-poly (methyl methacrylate) (PS-b-PMMA) diblock copolymer (BCP) films by thermal annealing on ITO substrate modified by a cross-linkable random copolymer, and then these films were immersed into the titanium oxide sol in acetic acid for a few hours. The acetic acid in the sol can selectively swell the PMMA component, which results in titanium oxide sol being loaded to the PMMA component selectively. Then the films were calcined at high temperature to remove the PS-b-PMMA block copolymer, and simultaneously the titanium oxide was transferred in situ to the substrate. As a result, a highly ordered array of nanoporous and nanopillar TiO2 thin film is observed on the ITO substrates depending upon the block copolymer used with PS and PMMA cylinder-forming components. In principle, it can be a general and versatile approach for fabricating functional nanoparticle arrays.
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Authors: Xiao Jun Hu, Xin Yan Hu, Zhi Zhang
Abstract: According to the principle of dynamic quenching a new ON-OFF fluorescent chemosensor for Cu2+ ions was designed, this chemosensor was composed of p-tert-butylthiacalix [arene (TCA),sodium dodecyl sulfate (SDS) and perylene through the form of self-assembly in aqueous solution. Addition of Cu2+ ions could result in a quenching of the fluorescence emission of perylene inside micelles, which due to intramicellar complex-fluorophore electron-transfer or energy-transfer effects induced by the complexation of TCA with the Cu2+ ions.The experimental results indicated that: Under the condition of TCA/perylene was 800/1, SDS concentration was 150mmol/L and pH value above 9, according to the fluorescence quenching ,within a certain range of the concentration of Cu2+ ion can be linearly determined.
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Authors: Zhi Zhang, Xiao Jun Hu, Jing Feng, Li Bin Niu
Abstract: According to the principle of dynamic quenching a new ON-OFF fluorescent chemosensor for Cu2+ ions was designed, this chemosensor was composed of sodium dodecyl benzene sulfonate (SDBS), p-tert-butylthiacalix[4]arene (TCA) and perylene through the form of self-assembly in aqueous solution. Addition of Cu2+ ions could result in a quenching of the fluorescence emission of perylene inside micelles, which is ascribed to intramicellar complex-fluorophore electron-transfer or energy-transfer effects induced by the complexation of TCA with the Cu2+ ions.The results of the experiment indicated that: With the condition of TCA/perylene = 1000/1, SDBS concentration was 50mmol/L and pH value above 7, concentration of Cu2+ ion can be linearly determined according to the fluorescence quenching in a certain range.
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Authors: Masafumi Yasuda, Terutake Hayashi, Masaki Michihata, Yasuhiro Takaya
Abstract: We proposed a novel technique for self-assembly of micro parts by using DNA hybridization. As the demand for MEMS is growing, research on the self-assembly of micro parts is required to achieve fabrication of functional devices consisted of diverse micro parts. Our method has a unique characteristic where the selective assembly can be performed. At the targeted substrate region functionalized by single-stranded DNA, only components functionalized by the complementary one are assembled successfully. This is due to the complementary properties of DNA, which consists of four different bases (adenine (A), cytosine (C), guanine (G), and thymine (T)). A of one strand always pairs with a T of another, and so does C with G. The characteristic enables batch fabrication of diverse micro parts by using several kinds of DNA properly. Therefore, our method can be applied to the fabrication of MEMS. In this paper, in order to verify the feasibility of the automatic positioning using DNA hybridization, we performed a fundamental experiment for addressing polystyrene microspheres (1, 2, 6μm diameter) on the DNA patterned glass substrate.
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Authors: Hao Tian, Yan Zhang, Yun Jiang Liu
Abstract: A series of titanium doped ordered mesoporous carbons (Ti-OMCs) were prepared by employing titanium modified resol as source for the first time. The effect of titanium content and F127 content on the microstructure of Ti-OMCs was investigated by X-ray diffraction (XRD), N2 sorption isothermal and Transmission electron microscopy (TEM). The results showed that regularity of products decreased with the increase of titanium content. A mesophase transformation from 2-D hexagonal (P6mm) to body-centered cubic () structure can be achieved by decreasing F127 content.
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Authors: Yun Suk Jo, Do-Kyung Kim, Young Keun Jeong, Kyung Ja Kim, Mamoun Muhammed
Abstract: A novel approach to load a hydrophilic bovine serum albumin (BSA) into the drug carriers was proposed in terms of thermosensitive dual-shell structures which were fabricated with poly(N-isopropylacrylamide), poly(lactide) and Au nanoparticles. Spherically well-defined dualshell structures were constructed by a modified-double-emulsion method (MDEM). The lower critical solubility temperature of the structures was shifted to 36.4 °C which was confirmed by UVVis spectroscopy.
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Authors: Yang Feng Huang, Ye Bin Cai, Hao Liu
Abstract: Bismuth sulfide (Bi2S3) nanorods were successfully fabricated by sonochemical aqueous solution. The morphology, crystallinity and composition of samples at various growth stages were investigated by transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD). The results showed that the Bi2S3 nuclei had an obvious tendency to arrange themselves in rod-like arrays over extended length scales under soft template. Moreover the crystallinity would be reinforced with the elongation of the aging periods. The growth mode of particle−to−particle by self-assembly under soft template was proposed. The band gap energy of Bi2S3 nanorods was estimated at about 1.36 eV by UV-Vis absorption spectroscopy.
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Authors: Yuan Ming Huang, Bao Gai Zhai, Qing Lan Ma
Abstract: We demonstrate that a bent-core liquid crystal 1,3-phenylene-bis(4-butoxybenzylidene amine) can write the Chinese character 人, which means a person in English, when the bent-core compound gets cooled from its isotropic phase. The polarized optical microscopic graphs illustrate that the bent-core molecules are able to self-assemble themselves into the Chinese character either in a sequential order or in a reverse order. Our results reveal that bent-core molecules have the capability of being smart materials.
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Authors: Hang Jun Ding, Zhou Yang, Huai Yang, Mei Xiang Wan
Abstract: PANI nanofibers with a really nanoscaled diameter of 20 ~ 30 nm and a high conductivity of 100 S/cm were successfully prepared by using FeCl3 · 6H2O as oxidant at the acidic dopant-free. Compared with other synthetic methods for nanostructures, this approach is most simple and cheap because of FeCl3 · 6H2O having two-function of oxidant and dopant at the same time, resulting in further simplifying reaction reagents. Characterizations of UV-visible, FTIR spectra, XRD as well as conductivity measured by four-probe method definitely proved the nanofibers oxidized by FeCl3 as oxidant at dopant-free are identical to the emeraldine salt form of PANI, although without external acidic dopant, and Cl- anion is incorporated the PANI main chain as counter-ion.
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