Extrusion Polymerization: Catalyzed Synthesis of Crystalline Linear Polyethylene Nanofibers Within a Mesoporous Silica

Kageyama, Kensuke; Tamazawa, Jun-ichi; Aida, Takuzo

doi:10.1126/science.285.5436.2113

Cited by 469 publications

(308 citation statements)

References 29 publications

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“…Infra-red (IR) spectra were recorded on an FT-IR Perkin-Elmer 2000 spectrophotometer. Solvents were dried and purified using standard procedures using N 3 X-ray diffraction (XRD) was carried out at room temperature on a Siemens D-5000 diffractometer with θ-2θ geometry. The XRD data was collected using Cu-Kα radiation (40 kV and 30 mA).…”

Section: Methodsmentioning

confidence: 99%

“…Reaction of N 3 P 3 Cl 6 with H 2 N(CH 2 ) 3 Si(OEt) 3 in the presence of triethylamine in toluene as a solvent, and at reflux yields N 3 P 3 [NH(CH 2 ) 3 Si(OEt) 3 ] 6 (1) as viscous in color liquid. The 31 P-NMR spectrum exhibits the typical signal at 0.72 ppm characteristic of N 3 P 3 (NR 2 ) 6 derivatives 12 (the spectrun is shown in supporting information S 1 ).…”

Section: Synthesis Of the Precursorsmentioning

confidence: 99%

“…The reaction of N 3 P 3 Cl 6 with H 2 N(CH 2 ) 3 Si(OEt) 3 31 P NMR spectrum for the compound (2) showed two resonances at 20.8 ppm. and 17.97 ppm(both nearly multiplets) with a relative intensity of 1:2, see supporting information , S 2 .…”

Section: Synthesis Of the Precursorsmentioning

confidence: 99%

“…The fabrication and study of silica (SiO 2 ) has received considerable attention in recent years, largely due to their potential in diverse applications (e.g. catalysis 2,3 ) other than in silicon-based electronic architectures. Their nanoscale counterparts enjoy resurgence in interest due in part to the fundamental differences in properties between the nanoscale and the bulk material 4 .…”

Section: Introductionmentioning

confidence: 99%

“…N P N P N P NH(CH 2 ) 3 Si(OEt) 3 (EtO) 3 Si(H 2 C) 3 HN NH(CH 2 ) 3 Si(OEt) 3 (EtO) 3 Si(H 2 C) 3 HN NH(CH 2 ) 3 Si(OEt) 3 (EtO) 3 Si(H 2 C) 3 Although polyphosphazenes have been previously used to stabilize gold nanoparticles in solution 11 , no examples of stabilization of metal nanoparticles by cyclic phosphazenes in solution or in solidstate have been reported. We previously reported on the synthesis and characterization of organometallic derivatives of cyclotriorganophosphazene 12 and here we detail the synthetic method and characterize several new organosilicon derivatives of cyclotriphosphazenes and their pyrolysis study.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Characterization of Cyclotriphosphazenes Containing Silicon as Single Solid-State Precursors for the Formation of Silicon/Phosphorus Nanostructured Materials

et al. 2008

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The synthesis and characterization of new organosilicon derivatives of N 3 P 3 Cl 6 , N 3 P 3 [NH(CH 2 ) 3 Si(OEt) 3 ] 6 (1),Pyrolysis of 1, 2, and 3 in air and at several temperatures results in nanostructured materials whose composition and morphology depend on the temperature of pyrolysis and the substituents of the phosphazenes ring. The products stem from the reaction of SiO 2 with P 2 O 5 , leading to either crystalline Si 5 (PO 4 ) 6 O, SiP 2 O 7 or an amorphous phase as the glass Si 5 (PO 4 ) 6 O/3SiO 2 • 2P 2 O 5 , depending on the temperature and nature of the trimer precursors. From 1 at 800 °C, core-shell microspheres of SiO 2 coated with Si 5 (PO 4 ) 6 O are obtained, while in other cases, mesoporous or dense structures are observed. Atomic force microscopy examination after deposition of the materials on monocrystalline silicon wafers evidences morphology strongly dependent on the precursors. Isolated islands of size ∼9 nm are observed from 1, whereas dense nanostructures with a mean height of 13 nm are formed from 3. Brunauer-Emmett-Teller measurements show mesoporous materials with low surface areas. The proposed growth mechanism involves the formation of cross-linking structures and of vacancies by carbonization of the organic matter, where the silicon compounds nucleate. Thus, for the first time, unique silicon nanostructured materials are obtained from cyclic phosphazenes containing silicon.

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Section: Methodsmentioning

confidence: 99%

Section: Synthesis Of the Precursorsmentioning

confidence: 99%

Section: Synthesis Of the Precursorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis and Characterization of Cyclotriphosphazenes Containing Silicon as Single Solid-State Precursors for the Formation of Silicon/Phosphorus Nanostructured Materials

et al. 2008

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New (Inter)Faces: Polymers and Inorganic Materials

2000

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A revolution in materials research is occurring at the interface of polymer and inorganic materials chemistry. [1] Two major sub-disciplines of chemistry, that not so long ago seemed self-contained, disconnected, and mature, are now being integrated in novel, imaginative, and important ways. Early explorations at the boundary between the fields are unveiling new classes of polymer±inorganic hybrid materials with structures and compositions unparalleled in materials science. The coalition of synthetic concepts and methods provides an approach to nanocomposite materials in which the interface between polymer and inorganic constituents is under molecular control. This alliance enables the design of hierarchical structures that may exhibit properties and functions unattainable with polymer and inorganic components alone. In this Research News article, some recent materials research occurring at the boundary of polymer/oligomer and inorganic materials chemistry is examined. This is intended to highlight the scientific vitality, excitement and opportunities that abound in this emerging field.There are many aspects of the work that are especially appealing and bode well for a vibrant future of research in this interdisciplinary area. The most attractive feature of the work is that polymer inorganic hybrid materials can exploit the chemical and physical attributes of both components in a new way. Thus, when integrated into a designer architecture with command of the interface between constituents at the molecular scale, the composite can display unique behavior not available to the polymer and inorganic parts alone. Another aspect that is particularly unusual concerns the amalgamation of structures and length scales typically associated with polymers and inorganics to create functional hybrid materials with hierarchical architectures that are unprecedented in materials science. Furthermore, the intentional combination of polymeric and inorganic building units in a self-assembly synthesis provides control over interfaces at the molecular scale. This new approach to synthesizing polymer±inorganic composite materials from the ªbottom-upº rather than fabricating them in the traditional way from the ªtop-downº, offers new ways to introduce function and form into materials for possible use in dental and bone implants, corrosion protection and battery electrolytes, dielectrics and food packaging, and vehicles for controlled chemical release. [2] Concepts and ExamplesSome examples that illustrate the benefits of integrating polymer/oligomer and solid-state materials chemistry are briefly mentioned in the following paragraphs. To begin, the impressive morphologies of microphase separated diblock and triblock copolymers have been utilized as templates to direct the hydrolytic polycondensation of metal alkoxides into mesoporous metal oxide, composite materials. [3,4] These hybrid materials have structures that can be considered as ªcastsº of the templating mesophase. The polymer template can be removed from the composite to produc...

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Immobilization – Homogeneous

Tóth

Geem

2002

Encyclopedia of Catalysis

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Supported or immobilized homogeneous catalysts combine the merit of easy separation of a heterogeneous catalyst with the uniform active sites and high performance of the homogeneous analogue. In ideal cases, these hybrid catalysts can provide higher selectivity/activity than that of the homogeneous counterparts because of synergetic effects with the support material or reluctance of the supported metal complexes to undergo undesirable dimerization or cluster formation. The immobilization of homogeneous catalyst to a chosen inorganic or polymer support can be achieved with various methods, which are reviewed and evaluated in this article. Thus, entries are made for physically attached catalysts, which are obtained by adsorbing metal complexes or their solutions (supported liquid‐phase) to solids, and by encapsulating or by entangling homogeneous catalysts to microporous solids or in polymers, respectively. Chemically attached catalysts are classified by the nature of binding to the support, ie, covalent or ionic binding of metal centers and/or ligands to supports. Furthermore, support materials and site isolation are also addressed in the article. Although the type of reaction with immobilized catalysts was not the basis for the overview, numerous examples are given for specific applications.

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Extrusion Polymerization: Catalyzed Synthesis of Crystalline Linear Polyethylene Nanofibers Within a Mesoporous Silica

Cited by 469 publications

References 29 publications

Synthesis and Characterization of Cyclotriphosphazenes Containing Silicon as Single Solid-State Precursors for the Formation of Silicon/Phosphorus Nanostructured Materials

Synthesis and Characterization of Cyclotriphosphazenes Containing Silicon as Single Solid-State Precursors for the Formation of Silicon/Phosphorus Nanostructured Materials

New (Inter)Faces: Polymers and Inorganic Materials

Immobilization – Homogeneous

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