نتایج جستجو برای: silica polymerization

تعداد نتایج: 67004  

Journal: :Journal of the American Chemical Society 2014
Yuying Meng Damien Voiry Anandarup Goswami Xiaoxin Zou Xiaoxi Huang Manish Chhowalla Zhongwu Liu Tewodros Asefa

Replacing rare and expensive metal catalysts with inexpensive and earth-abundant ones is currently among the major goals of sustainable chemistry. Herein we report the synthesis of N-, O-, and S-tridoped, polypyrrole-derived nanoporous carbons (NOSCs) that can serve as metal-free, selective electrocatalysts and catalysts for oxygen reduction reaction (ORR) and alcohol oxidation reaction (AOR), ...

Journal: :Chemcatchem 2022

Strict morphological control over growing polymer particles is an indispensable requirement in many catalytic olefin polymerization processes. In catalysts with mechanically stronger supports, e. g., polymerization-grade silicas, the emergence of extensive cracks via sectioning fragmentation mechanism requires severe stress build-up polymerizing catalyst particle. Here, we report on three facto...

2004
Benn C. Wilson Christopher W. Jones

n-Propylsulfonic acid-functionalized porous and nonporous silica materials are evaluated in the ring-opening polymerization of -caprolactone. All catalysts allow for the controlled polymerization of the monomer, producing polymers with controlled molecular weights and narrow polydispersities. Polymerization rates are low, with site-time yields generally 1-3 orders of magnitude lower than metalb...

A. Tadjarodi, M. Haghverdi M. Rajabi V. Mohammadi

The silica aerogel was prepared by the acid–base sol–gel polymerization of tetraethylorthosilicate precursor followed by ambient pressure drying. The prepared silica aerogels were characterized by Fourier transform infrared )FT-IR(, Thermo-gravimetric and differential thermal analysis )TG/DTA(, X-ray diffractometer )XRD(, Energy dispersive X-ray microanalysis )EDX(, Brunauer–Emmitt–Teller (BET)...

2002
Douglas H. Adamson Daniel M. Dabbs Daniel E. Morse Ilhan A. Aksay

Introduction A major challenge faced by ceramic chemists today is the production of fully polymerized silica by low temperature (< 50°C) solution routes. Current methods involve high temperature, extreme pH, or both. Biological systems, however, have the ability to produce silica under much more benign conditions. These include near neutral pH and temperatures at or below room temperature. Our ...

2015
Klara Altintoprak Axel Seidenstücker Alexander Welle Sabine Eiben Petia Atanasova Nina Stitz Alfred Plettl Joachim Bill Hartmut Gliemann Holger Jeske Dirk Rothenstein Fania Geiger Christina Wege

The coating of regular-shaped, readily available nanorod biotemplates with inorganic compounds has attracted increasing interest during recent years. The goal is an effective, bioinspired fabrication of fiber-reinforced composites and robust, miniaturized technical devices. Major challenges in the synthesis of applicable mineralized nanorods lie in selectivity and adjustability of the inorganic...

Journal: :Chemical communications 2011
Tomoki Ogoshi Keisuke Kitajima Shuhei Fujinami Tada-aki Yamagishi

The reaction of 1,4-dimethoxybenzene and paraformaldehyde using AlBr(3) yields multiple-deprotected pillar[5]arenes. A1/B2 di-deprotected pillar[5]arene can be isolated by silica gel chromatography and washing procedures. The X-ray structure and polymerization of the A1/B2 di-deprotected pillar[5]arene are reported.

Journal: :Chemical communications 2014
Lingxiao Li Bucheng Li Lei Wu Xia Zhao Junping Zhang

Porous silicone sponges are fabricated by polymerization of organosilanes in the presence of Fe3O4@silica nanoparticles. The sponges feature fast magnetic responsivity, superhydrophobicity/superoleophilicity, high compressibility and stability. The sponges can selectively absorb floating oils on a water surface, heavy oils under water and even emulsified oils.

2008
Abderrahmane Amgoune Marina Krumova Stefan Mecking

Homogeneous molecular catalysts are immobilzed in a well-defined fashion on individual silica nanoparticles with a narrow particle size distribution by covalent attachment. This synthetic methodology is demonstrated with modified salicylaldiminato-substituted titanium(IV) complexes incorporating a trimethoxysilaneterminated linker: dichloro-bis[κ2-N,O-6-(3-(trimethoxysilyl)propoxyphenylimino)-2...

Journal: :Langmuir : the ACS journal of surfaces and colloids 2012
Daisuke Nagao Maki Sugimoto Ayako Okada Haruyuki Ishii Mikio Konno Arnout Imhof Alfons van Blaaderen

Assembly and directed orientation of anisotropic particles with an external ac electric field in a range from 1 kHz to 2 MHz were studied for asymmetric composite dumbbells incorporating a silica, titania, or titania/silica (titania:silica = 75:25 vol %) sphere. The asymmetric composite dumbbells, which were composed of a polymethylmethacrylate (PMMA)-coated sphere (core-shell part) and a polys...

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