The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
Masaya Mitsuishi - One of the best experts on this subject based on the ideXlab platform.
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Cyclosiloxane polymer bearing dynamic boronic acid synthesis and bottom up nanocoating
Polymer Chemistry, 2019Co-Authors: Ali Demirci, Shunsuke Yamamoto, Tokuji Miyashita, Masaya MitsuishiAbstract:The paper describes facile synthesis of boronic ester-containing polyCyclosiloxane (pCS-ABPE) through a one-pot-two-step hydrosilylation reaction that allows control of the functionalization efficiency stoichiometrically from zero to 100%. The combination of Cyclosiloxane and boronic acid groups is expected to benefit from excellent thermal properties, flexible polymer backbone, and chemical resistance of the polyCyclosiloxane part and the dynamic chemical properties of the boronic acid part to generate novel and functional hybrid polymers. Results showed that the hydrolysis of pCS-ABPE gave rise to a boronic-acid-containing polycylcosiloxane (pCS-AB) with good self-assembly nanofilm formation (6 nm film thickness) on plastic substrates through dip-coating method, mainly because of its low surface free energy (∼20 mN m−1). In addition, the dynaminc characteristics of boronic acid groups in the pCS-AB film were demonstrated through water soluble dye Alizarin Red S (ARS) coating. The film surface underwent reversible coating through the boronic acid equilibrium: formation of the dynamic covalent bonding (pCS-AB-ARS) and bond deformation with Zn ions for ARS-Zn complex formation. The performance makes the self-assembly nanofilm promising for chemical sensor applications.
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facile synthesis of Cyclosiloxane based polymers for hybrid film formation
Polymer Chemistry, 2015Co-Authors: Ali Demirci, Shunsuke Yamamoto, Jun Matsui, Tokuji Miyashita, Masaya MitsuishiAbstract:A straightforward synthesis of Cyclosiloxane-based hybrid polymers and preparation of hybrid network polymer films were demonstrated. Cyclosiloxane-based hybrid polymers were prepared from one-step hydrosilylation of tetrasilane-functional Cyclosiloxanes with divinyl-terminated dimethylsiloxane monomers. Colorless and soluble hybrid polymers were obtained by controlling synthesis parameters such as the initial monomer ratio and the total monomer concentration. The 1H, 29Si NMR and FT–IR results revealed that the resulting hybrid polymers took practically linear structures with residual silane groups that enable us to crosslink hybrid polymers through subsequent condensation reactions with multi-step heat treatments. Consequently, flexible, thermally mechanically robust, optically transparent free-standing hybrid network polymer films were obtained with more than 90% optical transparency (0.2 mm thickness) in the UV–visible light wavelength region (>220 nm). Moreover, they had good thermal stability (approximately 300 °C) and approximately 400 MPa Young's modulus. Self-crosslinking reaction of residual Si–H groups in hybrid polymers contributed to the enhanced thermal and mechanical properties of hybrid polymer films because of the siloxane linkage conversion from R2SiO to the RSiO3/2 framework.
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luminescence properties of anthracene chromophores in Cyclosiloxane based hybrid polymer films
Rapid Communication in Photoscience, 2015Co-Authors: Ali Demirci, Shunsuke Yamamoto, Jun Matsui, Tokuji Miyashita, Masaya MitsuishiAbstract:ABSTRACT : Luminescence properties of anthracene chromophores were investigated. Anthracene chromophores were incorporated in Cyclosiloxane-based hybrid polymers through one-pot hydrosilylation reaction. Using four-armed Cyclosiloxanes, divinyl-terminated siloxane monomers, and 9-vinylanthracenes, anthracene-labeled hybrid polymers were prepared. Free-standing hybrid polymer films were prepared successfully by doctor-blade method and thermal treatment. The polymer films exhibit strong blue fluorescence from anthracene and its fluorescence lifetime was not influenced by the temperature, indicating that the movement of anthracene chromophores was restrained in Cyclosiloxane-based hybrid polymer films. Organic photonics and electronics have attracted much attention. 1,2 The enrichment of organic materials is beneficial to developing organic optoelectronics device applications. The ease of preparation also makes the organic device applications more attractive. Anthracene and its derivatives are good examples of organic optoelectronic device applications such as organic light emitting diodes, organic thin-film transistors, and photovoltaic cells.
Xiao Hu - One of the best experts on this subject based on the ideXlab platform.
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bio inspired reinforcement of Cyclosiloxane hybrid polymer via molecular stitching
Chemical Engineering Journal, 2019Co-Authors: Yujie Song, Yen Nan Liang, Liying Zhang, Xuelong Chen, Xiao HuAbstract:Abstract Cyclosiloxane hybrid polymer (CHP) was identified as a nacre-like structure, and was reinforced in a bio-inspired way through the incorporation of soft PDMS segment. Simultaneous improvement in both toughness and strength was observed, and the corresponding reinforcing mechanism was proposed to explain this phenomenon. It is believed that PDMS exited as two phases in the CHP. The homogeneously dispersed PDMS chains contribute positively to both the toughness and the strength via ‘molecular stitching', the phase separated PDMS particles improve the toughness but deteriorate the strength. Other types of siloxane-based additives were incorporated to prove the mechanism proposed.
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bioinspired reinforcement of Cyclosiloxane hybrid polymer
Chemical Communications, 2018Co-Authors: Yujie Song, Xiuzhi Tang, Yen Nan Liang, Liying Zhang, Shuguang Bi, Chenzhong Mu, Xiao HuAbstract:Structural analysis showed that Cyclosiloxane hybrid polymer (CHP) is a collection of nano-sized nacre-like structures in random orientations. Inspired by the reinforcement of nacre-like materials, basal-functionalized graphene (GO-AA) was inserted between CHP layers, acting as ‘double-sided tape’ to improve the mechanical properties. The resulting GO-AA/CHP nanocomposites showed a 156% improvement in toughness with only a 0.08 wt% loading of GO-AA, and a 25% improvement in thermal conductivity with a 0.10 wt% loading of GO-AA. The proposed ‘double-sided tape’ effect was also used to explain the highly efficient enhancement in thermal conductivity. This research promotes the application of CHP in harsher environments, demonstrates its prospects in thermal management areas, and contributes to nature-inspired materials design.
Ali Demirci - One of the best experts on this subject based on the ideXlab platform.
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Cyclosiloxane polymer bearing dynamic boronic acid synthesis and bottom up nanocoating
Polymer Chemistry, 2019Co-Authors: Ali Demirci, Shunsuke Yamamoto, Tokuji Miyashita, Masaya MitsuishiAbstract:The paper describes facile synthesis of boronic ester-containing polyCyclosiloxane (pCS-ABPE) through a one-pot-two-step hydrosilylation reaction that allows control of the functionalization efficiency stoichiometrically from zero to 100%. The combination of Cyclosiloxane and boronic acid groups is expected to benefit from excellent thermal properties, flexible polymer backbone, and chemical resistance of the polyCyclosiloxane part and the dynamic chemical properties of the boronic acid part to generate novel and functional hybrid polymers. Results showed that the hydrolysis of pCS-ABPE gave rise to a boronic-acid-containing polycylcosiloxane (pCS-AB) with good self-assembly nanofilm formation (6 nm film thickness) on plastic substrates through dip-coating method, mainly because of its low surface free energy (∼20 mN m−1). In addition, the dynaminc characteristics of boronic acid groups in the pCS-AB film were demonstrated through water soluble dye Alizarin Red S (ARS) coating. The film surface underwent reversible coating through the boronic acid equilibrium: formation of the dynamic covalent bonding (pCS-AB-ARS) and bond deformation with Zn ions for ARS-Zn complex formation. The performance makes the self-assembly nanofilm promising for chemical sensor applications.
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facile synthesis of Cyclosiloxane based polymers for hybrid film formation
Polymer Chemistry, 2015Co-Authors: Ali Demirci, Shunsuke Yamamoto, Jun Matsui, Tokuji Miyashita, Masaya MitsuishiAbstract:A straightforward synthesis of Cyclosiloxane-based hybrid polymers and preparation of hybrid network polymer films were demonstrated. Cyclosiloxane-based hybrid polymers were prepared from one-step hydrosilylation of tetrasilane-functional Cyclosiloxanes with divinyl-terminated dimethylsiloxane monomers. Colorless and soluble hybrid polymers were obtained by controlling synthesis parameters such as the initial monomer ratio and the total monomer concentration. The 1H, 29Si NMR and FT–IR results revealed that the resulting hybrid polymers took practically linear structures with residual silane groups that enable us to crosslink hybrid polymers through subsequent condensation reactions with multi-step heat treatments. Consequently, flexible, thermally mechanically robust, optically transparent free-standing hybrid network polymer films were obtained with more than 90% optical transparency (0.2 mm thickness) in the UV–visible light wavelength region (>220 nm). Moreover, they had good thermal stability (approximately 300 °C) and approximately 400 MPa Young's modulus. Self-crosslinking reaction of residual Si–H groups in hybrid polymers contributed to the enhanced thermal and mechanical properties of hybrid polymer films because of the siloxane linkage conversion from R2SiO to the RSiO3/2 framework.
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luminescence properties of anthracene chromophores in Cyclosiloxane based hybrid polymer films
Rapid Communication in Photoscience, 2015Co-Authors: Ali Demirci, Shunsuke Yamamoto, Jun Matsui, Tokuji Miyashita, Masaya MitsuishiAbstract:ABSTRACT : Luminescence properties of anthracene chromophores were investigated. Anthracene chromophores were incorporated in Cyclosiloxane-based hybrid polymers through one-pot hydrosilylation reaction. Using four-armed Cyclosiloxanes, divinyl-terminated siloxane monomers, and 9-vinylanthracenes, anthracene-labeled hybrid polymers were prepared. Free-standing hybrid polymer films were prepared successfully by doctor-blade method and thermal treatment. The polymer films exhibit strong blue fluorescence from anthracene and its fluorescence lifetime was not influenced by the temperature, indicating that the movement of anthracene chromophores was restrained in Cyclosiloxane-based hybrid polymer films. Organic photonics and electronics have attracted much attention. 1,2 The enrichment of organic materials is beneficial to developing organic optoelectronics device applications. The ease of preparation also makes the organic device applications more attractive. Anthracene and its derivatives are good examples of organic optoelectronic device applications such as organic light emitting diodes, organic thin-film transistors, and photovoltaic cells.
Carmen Racles - One of the best experts on this subject based on the ideXlab platform.
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A silica-silver nanocomposite obtained by sol-gel method in the presence of silver nanoparticles
Central European Journal of Chemistry, 2013Co-Authors: Carmen Racles, Alexandra Nistor, Maria CazacuAbstract:Silver nanoparticles (AgNPs) were obtained by a redox reaction, using a glucose-containing Cyclosiloxane as a reduction agent and stabilizer. Then the AgNPs aqueous solution was used as the reaction medium for the sol-gel process, starting from tetraethylorthosilicate (TEOS) as silica precursor. The nanocomposite material resulted (SilAg) after solvent removal, aging and calcination and was investigated by infrared spectroscopy (FT-IR), atomic force microscopy (AFM), scanning electron microscopy coupled with energy dispersive X-ray system (SEM/EDX), transmission electron microscopy (TEM), energy-dispersive X-ray fluorescence spectroscopy (EDXRF), X-ray diffraction (XRD) and dynamic vapor sorption (DVS). The results were compared to model silicas obtained without silver. A higher condensation degree in SilAg was obtained due to the basic medium used in the first step and was confirmed by a sorption capacity lower than for the model silicas. The solid surface area calculated with GAB analysis using DVS data for the water vapors is 210 m^2 g^−1. The nanocomposite showed good catalytic activity for hydrogen peroxide decomposition.
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A simple method for the preparation of colloidal polymer-supported silver nanoparticles
Journal of Nanoparticle Research, 2011Co-Authors: Carmen Racles, Florica Doroftei, Iuliana Stoica, Vasile CozanAbstract:Polysulfone−silver composite nanoparticles have been prepared by combining polymer nanoprecipitation and redox synthesis of silver, in the presence of a glucose-modified Cyclosiloxane as stabilizing agent. Based on previous kinetic investigations and on model reactions, we concluded that the reducing agent in this case is the tetrahydrofuran (THF) used as solvent for polysulfone. Dynamic light scattering measurements on the obtained polymer-silver composite particles indicated particle average diameter of 176 nm with a polydispersity index of 0.25. The UV–vis spectrum exhibited the silver plasmon resonance. By different microscopic methods (atomic force microscopy—AFM, high resolution transmission electron microscopy—HRTEM, and scanning electron microscopy—SEM), larger polymer particles coated with silver nanoprticles were observed. The Energy Dispersive X-Ray analysis—EDX; confirmed the presence of Ag on the surface of the particles, while the selected area electron diffraction showed single crystalline silver nanospheres with face-centered cubic structure.
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Silver nanoparticles obtained with a glucose modified siloxane surfactant
Journal of Nanoparticle Research, 2010Co-Authors: Carmen Racles, Iuliana Stoica, Anton Airinei, Aurelia IoanidAbstract:Silver nanoparticles were obtained in aqueous medium, at room temperature, by redox reactions, with or without glucose, in the presence of a glucose-containing Cyclosiloxane. The siloxane surfactant can act as stabilizer when glucose is present in the system, but also as reducing agent and stabilizer when no glucose is added. The kinetics was followed by absorption UV–Vis spectroscopy, and different behaviors were found for the two versions of the redox process: first-order kinetics for the reaction with glucose and a much slower complex reaction with three zero-order steps when no glucose was added. The reactions were also investigated with IR absorption spectroscopy. The resulting nanoparticles were analyzed by dynamic light scattering (DLS), atomic force microscopy (AFM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) analysis, and transmision electron microscopy (TEM). All data showed evidence for the formation of silver spherical nanoparticles, with an average diameter of 14 nm (reaction with glucose) and 6.5 nm (reaction without glucose), respectively.
Yujie Song - One of the best experts on this subject based on the ideXlab platform.
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bio inspired reinforcement of Cyclosiloxane hybrid polymer via molecular stitching
Chemical Engineering Journal, 2019Co-Authors: Yujie Song, Yen Nan Liang, Liying Zhang, Xuelong Chen, Xiao HuAbstract:Abstract Cyclosiloxane hybrid polymer (CHP) was identified as a nacre-like structure, and was reinforced in a bio-inspired way through the incorporation of soft PDMS segment. Simultaneous improvement in both toughness and strength was observed, and the corresponding reinforcing mechanism was proposed to explain this phenomenon. It is believed that PDMS exited as two phases in the CHP. The homogeneously dispersed PDMS chains contribute positively to both the toughness and the strength via ‘molecular stitching', the phase separated PDMS particles improve the toughness but deteriorate the strength. Other types of siloxane-based additives were incorporated to prove the mechanism proposed.
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bioinspired reinforcement of Cyclosiloxane hybrid polymer
Chemical Communications, 2018Co-Authors: Yujie Song, Xiuzhi Tang, Yen Nan Liang, Liying Zhang, Shuguang Bi, Chenzhong Mu, Xiao HuAbstract:Structural analysis showed that Cyclosiloxane hybrid polymer (CHP) is a collection of nano-sized nacre-like structures in random orientations. Inspired by the reinforcement of nacre-like materials, basal-functionalized graphene (GO-AA) was inserted between CHP layers, acting as ‘double-sided tape’ to improve the mechanical properties. The resulting GO-AA/CHP nanocomposites showed a 156% improvement in toughness with only a 0.08 wt% loading of GO-AA, and a 25% improvement in thermal conductivity with a 0.10 wt% loading of GO-AA. The proposed ‘double-sided tape’ effect was also used to explain the highly efficient enhancement in thermal conductivity. This research promotes the application of CHP in harsher environments, demonstrates its prospects in thermal management areas, and contributes to nature-inspired materials design.
