The Experts below are selected from a list of 14088 Experts worldwide ranked by ideXlab platform
Christopher J. Ellison - One of the best experts on this subject based on the ideXlab platform.
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Generating Large Thermally Stable Marangoni-Driven Topography in Polymer Films by Stabilizing the Surface Energy Gradient
Macromolecules, 2017Co-Authors: Amanda R. Jones, Chae Bin Kim, Sunshine X. Zhou, Reika Katsumata, Gregory Blachut, Roger T. Bonnecaze, Christopher J. EllisonAbstract:Marangoni forces drive a fluid to flow in response to positional differences in surface energy. In thin polymer films, a difference in surface energy between two coincident liquid polymers could offer a useful route to manufacture topographically patterned surfaces via the Marangoni effect. Previously, we have demonstrated a Photochemical Method using the Marangoni effect for patterning thin polystyrene films. To generalize the approach, a theoretical model that gives the underlying physics of this process was also developed, which further revealed that low viscosities, low diffusivities, and large surface energy gradients favor rapid evolution of large film thickness variations. However, as described by the Stokes−Einstein equation or the Rouse model, low viscosity is generally correlated with high diffusivity in a single-component system. Herein, we report a strategy to decouple film viscosity and diffusivity by co-casting a high molecular weight surface energy gradient creating copolymer (low diffusivi...
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Generating Large Thermally Stable Marangoni-Driven Topography in Polymer Films by Stabilizing the Surface Energy Gradient
2017Co-Authors: Amanda R. Jones, Sunshine X. Zhou, Reika Katsumata, Gregory Blachut, Roger T. Bonnecaze, Chae Bin Kim, Christopher J. EllisonAbstract:Marangoni forces drive a fluid to flow in response to positional differences in surface energy. In thin polymer films, a difference in surface energy between two coincident liquid polymers could offer a useful route to manufacture topographically patterned surfaces via the Marangoni effect. Previously, we have demonstrated a Photochemical Method using the Marangoni effect for patterning thin polystyrene films. To generalize the approach, a theoretical model that gives the underlying physics of this process was also developed, which further revealed that low viscosities, low diffusivities, and large surface energy gradients favor rapid evolution of large film thickness variations. However, as described by the Stokes−Einstein equation or the Rouse model, low viscosity is generally correlated with high diffusivity in a single-component system. Herein, we report a strategy to decouple film viscosity and diffusivity by co-casting a high molecular weight surface energy gradient creating copolymer (low diffusivity) with a low molecular weight majority homopolymer (high diffusivity and low viscosity), which are miscible with each other. Patterned light exposure through a photomask imposes a patterned surface energy gradient between light-exposed and unexposed regions due to Photochemical reactions involving only the low diffusivity component. Upon heating the film to the liquid state, the film materials (primarily the low viscosity homopolymer component) flow from the low to high surface energy regions. This strategy either eliminates or greatly slows dissipation of the prepatterned surface energy gradient while maintaining rapid feature formation, resulting in formation of ca. 500 nm high features within only 30 min of thermal annealing. Furthermore, the formed features are stable upon extended thermal annealing for up to one month. It is found that a ratio of Marangoni forces to capillary forces can provide a predictive metric that distinguishes which scenarios produce features that dissipate or persist
Qun Xiang - One of the best experts on this subject based on the ideXlab platform.
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ag nanoparticle embedded zno nanorods synthesized via a Photochemical Method and its gas sensing properties
Sensors and Actuators B-chemical, 2010Co-Authors: Qun Xiang, Guifang Meng, Yuan Zhang, Qingyi PanAbstract:A facile Photochemical Method was used to synthesize Ag nanoparticle (Ag NP) embedded-ZnO nanorods in this article. The as-synthesized Ag NP embedded-ZnO nanorod samples were characterized systematically by TEM, XPS, DSC, XRD and SEM. The characterization results confirmed that Ag NPs had been embedded in ZnO nanorods. The gas-sensing properties of Ag NP embedded-ZnO nanorods were also investigated. While the performances of the sensors can be enhanced by embedding Ag NPs onto the surfaces of ZnO nanorods, the response of Ag NP embedded-ZnO nanorod sensors to 50 ppm ethanol is almost three times as high as that of those made from pure-ZnO nanorods. The responses of the sensors have no apparent degradation after being exposed to ethanol of 30 ppm for 100 days. Our Ag NP embedded-ZnO nanorod sensors have long-term stability and exhibit highly enhanced gas-sensing performances in their response and selectivity for detecting ethanol vapor.
Qingyi Pan - One of the best experts on this subject based on the ideXlab platform.
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ag nanoparticle embedded zno nanorods synthesized via a Photochemical Method and its gas sensing properties
Sensors and Actuators B-chemical, 2010Co-Authors: Qun Xiang, Guifang Meng, Yuan Zhang, Qingyi PanAbstract:A facile Photochemical Method was used to synthesize Ag nanoparticle (Ag NP) embedded-ZnO nanorods in this article. The as-synthesized Ag NP embedded-ZnO nanorod samples were characterized systematically by TEM, XPS, DSC, XRD and SEM. The characterization results confirmed that Ag NPs had been embedded in ZnO nanorods. The gas-sensing properties of Ag NP embedded-ZnO nanorods were also investigated. While the performances of the sensors can be enhanced by embedding Ag NPs onto the surfaces of ZnO nanorods, the response of Ag NP embedded-ZnO nanorod sensors to 50 ppm ethanol is almost three times as high as that of those made from pure-ZnO nanorods. The responses of the sensors have no apparent degradation after being exposed to ethanol of 30 ppm for 100 days. Our Ag NP embedded-ZnO nanorod sensors have long-term stability and exhibit highly enhanced gas-sensing performances in their response and selectivity for detecting ethanol vapor.
Yuan Zhang - One of the best experts on this subject based on the ideXlab platform.
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ag nanoparticle embedded zno nanorods synthesized via a Photochemical Method and its gas sensing properties
Sensors and Actuators B-chemical, 2010Co-Authors: Qun Xiang, Guifang Meng, Yuan Zhang, Qingyi PanAbstract:A facile Photochemical Method was used to synthesize Ag nanoparticle (Ag NP) embedded-ZnO nanorods in this article. The as-synthesized Ag NP embedded-ZnO nanorod samples were characterized systematically by TEM, XPS, DSC, XRD and SEM. The characterization results confirmed that Ag NPs had been embedded in ZnO nanorods. The gas-sensing properties of Ag NP embedded-ZnO nanorods were also investigated. While the performances of the sensors can be enhanced by embedding Ag NPs onto the surfaces of ZnO nanorods, the response of Ag NP embedded-ZnO nanorod sensors to 50 ppm ethanol is almost three times as high as that of those made from pure-ZnO nanorods. The responses of the sensors have no apparent degradation after being exposed to ethanol of 30 ppm for 100 days. Our Ag NP embedded-ZnO nanorod sensors have long-term stability and exhibit highly enhanced gas-sensing performances in their response and selectivity for detecting ethanol vapor.
Campomanes Santana, Ruth Marlene - One of the best experts on this subject based on the ideXlab platform.
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Sintese fotoquimica de compositos semicondutores eletricos de poli(pirrol)-poli(vinil alcool)
[s.n.], 2019Co-Authors: Campomanes Santana, Ruth MarleneAbstract:Orientador: Edison BittencourtTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuimicaResumo: Este trabalho mostra um de novo método de obter compósitos semicondutores elétricos poli(pirrol )-poli( vinil álcool) (PPy-PV A), polimerizado por via fotoquímica, via luz UV e na presença do sal de ferro-areno como fotoiniciador. Estudos gravimétricos tem mostrado que o rendimento de polimerização do PPy incidente na matriz de PVA é fortemente influenciado pelo tempo de umectação da matriz na solução monomérica, natureza do solvente, concentração do fotoiniciador e da dose de irradiação. Foi realizado o estudo cinético da polimerização do PPy com e sem a presença do solvente (metanol), no qual demostrou-se que o método fotoquímico é o mais rápido e eficiente. Foi realizada a dopagem dos compósitos com os ácidos: p-toluenosulfônico (APTS), naftalenosulfônico (ANS) e dodecilbenzeno sulfônico (ADBS) com a finalidade de avaliar a estabilidade da condutividade dos compósitos em função do tempo de armazenagem, sendo os melhores resultados dos compósitos dopados com APTS...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digitalAbstract: The goal of this work is to show a new Method to obtain semiconducting composites of poly(pyrrol)-poly(vinyl aleohol) PPy-PVA polymerized Photochemically, via UV light and the iron-arene salt as photoinitiator. Gravimetric studies have shown that the yield of polymerization of PPy inside the PVA matrix is influenced strongly by several factors: swelling time of PVA matrix in the monomeric solution, the solvent nature, the photoinitiator concentration and the irradiation dose. It was performed a kinetic study of PPy polymerization with the presence of the solvent (methanol), and without it showing that the Photochemical Method is the most rapid and efficient. It was also performed the dopant of composites with acids such as: p-toluene sulfonic (APTS), naphtalenosulfonic (ANS) and dodecilbenzene sulfonie (ADBS) with the objective to evaluate the stability of composites conductivity in function of storage time. The best results were found using APTS...Note: The complete abstract is available with the full electronic digital thesis or dissertationsDoutoradoCiencia e Tecnologia de MateriaisDoutor em Engenharia Químic