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Richard M Laine - One of the best experts on this subject based on the ideXlab platform.
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Synthesis and Characterization of Organic/Inorganic Epoxy Nanocomposites from Poly(aminopropyl/phenyl)Silsesquioxanes
2016Co-Authors: Chavakorn Samthong, Richard M Laine, Anongnat SomwangthanarojAbstract:ABSTRACT: Organic/inorganic epoxy nanocomposites containing diglycidyl ether of bisphenol A (DGEBA), 4-methylhexahydrophthalic anhydride (MHHPA) and poly(aminopropyl/phenyl) Silsesquioxanes (PAPPS) were prepared and characterized. PAPPS were synthesized via fluoride-catalyzed cage formation from random-structured poly(phenyl)Silsesquioxane (PPS) and 3-aminopropyltriethoxysilane (APTES) in tetrahydrofuran (THF) using tetrabutylammonium fluoride (TBAF) catalyst containing substantial water. The PPS/APTES stoichiometric ratios were varied. The FTIR, 1H, solid-state 29Si-NMR studies show that PAPPS probably consists of cages, partial cages, and some linear structures containing phenyl and aminopropyl functional groups. The amine content was determined by back titration and elemental analysis. In comparison with neat epoxy, incorporation of these materials can improve the resultant thermal stabilities, raise glass transition temperatures (Tgs), and reduce coefficients of thermal expansion (CTEs) of epoxy nanocomposites as confirmed b
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halogen bonding motifs in polyhedral phenylSilsesquioxanes effects of systematic variations in geometry or substitution
Crystal Growth & Design, 2011Co-Authors: Mark F Roll, Jeffrey W Kampf, Richard M LaineAbstract:Herein we describe the halogen bonding coordination found in the crystal structures of two homologous series of hybrid Silsesquioxane (Polyhedral Oligomeric SilsesquioxaneS, or POSS) molecules, wit...
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toughening of cubic Silsesquioxane epoxy nanocomposites using core shell rubber particles a three component hybrid system
Macromolecules, 2004Co-Authors: Jiwon Choi, And Albert F Yee, Richard M LaineAbstract:This study explores the concept of composite construction simultaneously at nano- and macroscopic length scales. This approach promises to allow improvement of multiple properties coincidentally but independently. A model system was identified that allows us to test this concept by combining molecular level hybridization using a Silsesquioxane epoxy nanocomposite with macroscopic modification using core−shell rubber particles (CSR). The objective here was to form an epoxy resin system with enhanced thermal stability, elastic modulus, and fracture toughness. The nanocomposite was made by reacting octa(dimethylsiloxyethylcyclohexyl epoxide)Silsesquioxane (OC, 1.3 nm diameter) with diaminodiphenylmethane (DDM). This resin offers excellent elastic moduli and thermal stabilities at the expense of poor fracture toughness. OC/DDM is a “single phase” hybrid nanocomposite that is used here as a matrix for ≈100 nm diameter CSR reinforcing particles. Characterization of OC/DDM/CSR composites shows that fracture toug...
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organic inorganic hybrid composites from cubic Silsesquioxanes epoxy resins of octa dimethylsiloxyethylcyclohexylepoxide Silsesquioxane
Macromolecules, 2003Co-Authors: Jiwon Choi, And Albert F Yee, Richard M LaineAbstract:Standard research protocols were developed to explore the use of octahedral Silsesquioxane (cube) organic/inorganic nanocomposites as model systems for determining nanostructure−processing−property relationships to demonstrate that nanoscale structural manipulation of the organic component can significantly change macroscale physical properties. Comparison of octaglycidyldimethylsiloxyoctaSilsesquioxane [(glycidyl-Me2SiOSiO1.5)8] (OG)/diaminodiphenylmethane (DDM) and octa(ethylcyclohexylepoxide)dimethylsiloxy Silsesquioxane (OC)/DDM nanocomposite resins provide the first demonstration that well-defined nanostructures can be formed wherein linear organic tethers of known structure join only two cube vertices. HF dissolution of cubes followed by GPC analysis demonstrates that only linear tethers form in OC/DDM. TEM studies suggest that these nanocomposites are homogeneous at the nanometer scale, thus supporting the chemical analysis studies. The physical properties of these nanocomposites were then systemat...
Tianyu Wang - One of the best experts on this subject based on the ideXlab platform.
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influence of fibre surface oxidation reduction followed by Silsesquioxane coating treatment on interfacial mechanical properties of carbon fibre polyarylacetylene composites
Composites Part A-applied Science and Manufacturing, 2007Co-Authors: X X Zhang, Yudong Huang, Tianyu Wang, Li LiuAbstract:Carbon fibre was treated with oxidation–reduction followed by Silsesquioxane coating method to improve the interfacial properties of carbon fibre/polyarylacetylene (CF/PAA) composites. The treatment method was divided into three phases, i.e., oxidation with oxygen plasma, reduction with LiAlH4, and coating treatment with vinyl Silsesquioxane (VMS–SSO). The fibre surface composition and functional group were analyzed using X-ray photoelectron spectroscopy (XPS). The polar functional groups, especially C–OH which could react with Si–OH on Silsesquioxanes, were increased after redox reaction. VMS–SSO coating treatment imported vinyl groups which could react with PAA resin during PAA cure process. The surface morphology of carbon fibre was observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The mechanical interfacial properties of the CF/PAA composites were characterized by short-beam bending testing method. Interlaminar shear strength (ILSS) of the CF/PAA composites in different treatment phases were increased by 31.7%, 28.8%, and 59.3%, respectively. The conclusion that oxidation–reduction followed by Silsesquioxane coating treatment is an effective method to improve the interfacial properties of the CF/PAA composites can be drawn. This method can be used in other resin systems if the functional groups on Silsesquioxane are changed according to those in resins. � 2006 Elsevier Ltd. All rights reserved.
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effects of Silsesquioxane coating structure on mechanical interfacial properties of carbon fibre polyarylacetylene composites
Journal of Materials Science, 2007Co-Authors: X X Zhang, Yudong Huang, Tianyu WangAbstract:Carbon fibres (CF) were treated with different coatings, including [3-(methacryloxy)propyl]trimethoxylsilane (MPMS), [3-(methacryloxy)propyl]Silsesquioxane (MPMS-SSO), and (methacryloxy)propyl polyhedral oligomeric Silsesquioxane (Methacryl-POSS), to improve the interfacial properties of carbon fibre reinforced polyarylacetylene (PAA) matrix composites. MPMS-SSO was obtained from the hydrolytic condensation of MPMS. The complicated structure, including cage and ladder one, of MPMS-SSO may be assigned by Fourier transforms infrared (FT-IR) spectra, 1H, 13C and 29Si nuclear magnetic resonance (NMR) and ultraviolet matrix-assisted laser desorption ionization time-of-flight mass spectrometry (UV-MALDI-TOF MS). Interlaminar shear strength (ILSS) was tested to investigate the effect of coating structure on the interfacial bonding. The values of ILSS of untreated and treated CF/PAA composites with different coatings (MPMS, MPMS-SSO and Methacryl-POSS) show that the treatment effect of Methacryl-POSS coating is the best one and the MPMS-SSO coating is better than that of MPMS coating. SEM micrographs of shear fracture of CF/PAA composites also suggested the different coating treatment effects. The differences of increasing degrees of ILSS indicate that the structure of coating is important when Silsesquioxanes are used as coatings to treat fibre surface for building up the adhesion and improving interfacial properties of fibre reinforced polymer matrix composites.
Chaobin He - One of the best experts on this subject based on the ideXlab platform.
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photoactive perylenediimide bridged Silsesquioxane functionalized periodic mesoporous organosilica thin films pmo sba15 synthesis self assembly and photoluminescent and enhanced mechanical properties
Langmuir, 2009Co-Authors: Abdul M Wahab, Hazrat Hussain, Chaobin HeAbstract:Well-organized periodic mesoporous organosilica thin films (designated as PMO-SBA15), having covalently bonded perylene-bridged silesquioxane (PTCDBS) inside their pore channels, are successfully synthesized via sol−gel self-assembly of 1,2-bis(triethoxysilyl)ethane and perylene-bridged Silsesquioxane, using micelles of pluronic surfactant (P123) as a template for the first time. The surfactant is successfully removed from the pore channels of PMO-SBA15 by an acidic solvent extraction procedure. The final PMO-SBA15 thin films are characterized by high resolution X-ray diffraction (HRXRD), transmission electron microcopy (TEM), solid-state 29Si and 13C NMR CP/MAS NMR spectroscopy, nitrogen adsorption−desorption measurements, photoluminescence (PL) spectroscopy, and nanoindentation. HRXRD data reveal the formation of well-organized hexagonal channels in the pure PMO-SBA15 films. The intensity of the diffracted X-ray, however, systematically attenuates after incorporation of the perylene functionality inside...
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polyimide poss nanocomposites interfacial interaction thermal properties and mechanical properties
Polymer, 2003Co-Authors: Junchao Huang, Chaobin He, Yang Xiao, Yeen Ping SiowAbstract:Abstract A series of functional polyhedral oligomer silsesquioxnae (POSS)/polyimide (PI) nanocomposites were prepared using a two-step approach, first, the octa(aminophenyl)Silsesquioxane (OAPS)/NMP solution was mixed with polyamic acid (PAA) solution prepared by reacting 4,4′-diaminodiphenylmethane and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride in NMP, and second, the polycondensation solution was treated by thermal imidization. The well-defined ‘hard particles’ (POSS) and the strong covalent bonds between the PI and the ‘hard particles’ lead to a significant improvement in the thermal mechanical properties of the resulting nanocomposites. The glass transition temperature dramatically increases while the coefficient of thermal expansion (CTE) decreases, owing to the significant increase of the cross-linking density in the PI–POSS nanocomposites. The thermal stability and mechanical property of the nanocomposites were also improved.
X X Zhang - One of the best experts on this subject based on the ideXlab platform.
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influence of fibre surface oxidation reduction followed by Silsesquioxane coating treatment on interfacial mechanical properties of carbon fibre polyarylacetylene composites
Composites Part A-applied Science and Manufacturing, 2007Co-Authors: X X Zhang, Yudong Huang, Tianyu Wang, Li LiuAbstract:Carbon fibre was treated with oxidation–reduction followed by Silsesquioxane coating method to improve the interfacial properties of carbon fibre/polyarylacetylene (CF/PAA) composites. The treatment method was divided into three phases, i.e., oxidation with oxygen plasma, reduction with LiAlH4, and coating treatment with vinyl Silsesquioxane (VMS–SSO). The fibre surface composition and functional group were analyzed using X-ray photoelectron spectroscopy (XPS). The polar functional groups, especially C–OH which could react with Si–OH on Silsesquioxanes, were increased after redox reaction. VMS–SSO coating treatment imported vinyl groups which could react with PAA resin during PAA cure process. The surface morphology of carbon fibre was observed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The mechanical interfacial properties of the CF/PAA composites were characterized by short-beam bending testing method. Interlaminar shear strength (ILSS) of the CF/PAA composites in different treatment phases were increased by 31.7%, 28.8%, and 59.3%, respectively. The conclusion that oxidation–reduction followed by Silsesquioxane coating treatment is an effective method to improve the interfacial properties of the CF/PAA composites can be drawn. This method can be used in other resin systems if the functional groups on Silsesquioxane are changed according to those in resins. � 2006 Elsevier Ltd. All rights reserved.
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effects of Silsesquioxane coating structure on mechanical interfacial properties of carbon fibre polyarylacetylene composites
Journal of Materials Science, 2007Co-Authors: X X Zhang, Yudong Huang, Tianyu WangAbstract:Carbon fibres (CF) were treated with different coatings, including [3-(methacryloxy)propyl]trimethoxylsilane (MPMS), [3-(methacryloxy)propyl]Silsesquioxane (MPMS-SSO), and (methacryloxy)propyl polyhedral oligomeric Silsesquioxane (Methacryl-POSS), to improve the interfacial properties of carbon fibre reinforced polyarylacetylene (PAA) matrix composites. MPMS-SSO was obtained from the hydrolytic condensation of MPMS. The complicated structure, including cage and ladder one, of MPMS-SSO may be assigned by Fourier transforms infrared (FT-IR) spectra, 1H, 13C and 29Si nuclear magnetic resonance (NMR) and ultraviolet matrix-assisted laser desorption ionization time-of-flight mass spectrometry (UV-MALDI-TOF MS). Interlaminar shear strength (ILSS) was tested to investigate the effect of coating structure on the interfacial bonding. The values of ILSS of untreated and treated CF/PAA composites with different coatings (MPMS, MPMS-SSO and Methacryl-POSS) show that the treatment effect of Methacryl-POSS coating is the best one and the MPMS-SSO coating is better than that of MPMS coating. SEM micrographs of shear fracture of CF/PAA composites also suggested the different coating treatment effects. The differences of increasing degrees of ILSS indicate that the structure of coating is important when Silsesquioxanes are used as coatings to treat fibre surface for building up the adhesion and improving interfacial properties of fibre reinforced polymer matrix composites.
Geoffrey A. Ozin - One of the best experts on this subject based on the ideXlab platform.
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spin coated periodic mesoporous organosilica thin films towards a new generation of low dielectric constant materials
Advanced Functional Materials, 2005Co-Authors: Benjamin Hatton, Wesley Whitnall, Kai Landskron, D D Perovic, Geoffrey A. OzinAbstract:Periodic mesoporous organosilica (PMO) thin films have been produced using an evaporation-induced self-assembly (EISA) spin-coating procedure and a cationic surfactant template. The precursors are Silsesquioxanes of the type (C 2 H S O) 3 Si-R-Si(OC 2 H 5 ) 3 or R'-[Si(OC 2 H 5 ) 3 ] 3 with R = methene (-CH 2 -), ethylene (-C 2 H 2 -), ethene (-C 2 H 4 -), 1,4-phenylene (C 6 H 4 ). and R'= 1,3,5-phenylene (C 6 H 3 ). The surfactant is successfully removed by solvent extraction or calcination without any significant Si-C bond cleavage of the organic bridging groups R and R' within the channel walls. The materials have been characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and 2 9 Si and 1 3 C magic-angle spinning (MAS) NMR spectroscopy. The d-spacing of the PMOs is found to be a function of R. Nanoindentation measurements reveal increased mechanical strength and stiffness for the PMOs with R = CH 2 and C 2 H 4 compared to silica. Films with different organic-group content have been prepared using mixtures of Silsesquioxane and tetramethylorthosilicate (TMOS) precursors. The dielectric constant (k) is found to decrease with organic content, and values as low as 1.8 have been measured for films thermally treated to cause a "self-hydrophobizing" bridging-to-terminal transformation of the methene to methyl groups with concomitant loss of silanols. Increasing the organic content and thermal treatment also increases the resistance to moisture adsorption in 60 and 80%-relative-humidity (RH) environments. Methene PMO films treated at 500°C are found to be practically unchanged after five days exposure to 80 % RH. These low dielectric constants. plus the good thermal and mechanical stability and the hydrophobicity suggest the potential utility of these films as low-k layers in microelectronics.
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Hybrid Periodic Mesoporous Organosilicas
Advanced Functional Materials, 2005Co-Authors: Wesley Whitnall, Tewodros Asefa, Geoffrey A. OzinAbstract:In this study we report the synthesis of a new class of materials called hybrid periodic mesoporous organosilicas (HPMOs). By coupling a Silsesquioxane precursor through at least two chemical linkages to the mesopore walls of a pre-existing periodic mesoporous silica (PMS) or periodic mesoporous organosilica (PMO). Many of the problems of a conventional PMO material can be avoided while ensuring efficient use of the bridging organic functional groups of the Silsesquioxane. We demonstrate this concept for PMS by anchoring various Silsesquioxanes, such as ethene and ethane Silsesquioxanes, to the mesopore walls of the PMS. The addition of anchored Silsesquioxane monolayers and multilayers to the mesopore walls also allows for the strict control of the diameter of the mesopore as well as the mesopore wall thickness in the final HPMO material. Additionally it is shown that having the Silsesquioxane located solely on the surface of the mesopores in HPMOs gives increased chemical accessibility of the organic bridge-bonded moiety when compared with their PMO counterparts containing the bridge-bonded organic both on the surface and within the pore walls.
