The syntheses of a family of highly ordered mesoporous polymers and carbon frameworks from organic−organic assembly of triblock copolymers with soluble, low-molecular-weight phenolic resin precursors (resols) by an evaporation induced self-assembly strategy have been reported in detail. The family members include two-dimensional hexagonal (space group, p6m), three-dimensional bicontinuous (Ia3̄d), body-centered cubic (Im3̄m), and lamellar mesostructures, which are controlled by simply adjusting the ratio of phenol/template or poly(ethylene oxide)/poly(propylene oxide) in the templates. A five-step mechanism from organic−organic assembly has been demonstrated. Cubic FDU-14 with a gyroidal mesostructure of polymer resin or carbon has been synthesized for the first time by using the copolymer Pluronic P123 as a template in a relatively narrow range. Upon calcination at 350 °C, the templates should be removed to obtain mesoporous polymers, and further heating at above a critical temperature of 600 °C transforms the mesoporous polymers to the homologous carbon frameworks. The mesoporous polymer resin and carbon product materials exhibit ordered structures, high surface areas, (670−1490 m2/g), large pore volumes (0.65−0.85 cm3/g), and uniform, large pore sizes (7.0−3.9 nm), as well as very thick pore walls (6−8 nm). The carbon open frameworks with covalently bonded constructions and thick pore walls exhibit high thermal stability (>1400 °C). Our results show that the feed gas used during the calcination has a great influence on the porosity of the products. The presence of a small amount of oxygen facilitates the large pore sizes and high surface areas of mesoporous materials with different mesostructures. An extraction method employing sulfuric acid can also decompose the template from hexagonal mesostructured polymers with little framework shrinkage. Preliminary studies of the mechanical and electrochemical properties of mesoporous carbon molecular sieves are also presented.
From polymer templates to mesoporous materials: With the reverse amphiphilic triblock copolymer PPO-PEO-PPO and a resol resin precursor an organic–organic self-assembly process leads to the formation of an ordered polymer and a carbon mesostructure with a face-centered-cubic Fdm symmetry and bimodal pores (see scheme). PPO=polypropylenoxide, PEO=polyethylenoxide. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2007/z603665_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Large-sized, crack-free silica monoliths with highly ordered mesostructure are prepared by a fast and easy way via liquid-paraffin-medium protected solvent evaporation. By employing the inert liquid paraffin as the morphology "protector", cracks of the materials can be successfully avoided and the processing time can be reduced to 8 h. The block copolymer−silica composite monoliths are transparent and crack-free with a large size. The mesoporous silica monoliths have been characterized by small-angle powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and nitrogen adsorption, which show that the materials have a highly ordered hexagonal mesostructure of space group p6mm and narrow pore size distribution, with a mean pore diameter of 5.65 nm. In addition, metal ions can be easily doped into the monoliths, indicating potential optical, electronic, magnetic, and catalytic properties. This fast synthetic method is valuable for the applications of mesostructured silica monoliths in optics and separation.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
To improve the dust control efficiency of soil for backfilling at construction sites, a novel waterborne polymer was used as a dust suppressant, and the dust emission model was created to control the effect of a large-scale field. The results showed that the waterborne polymer could improve the water retention efficiency of soil for backfilling, and the average water content was 2.18 times that of the watered samples, significantly delaying water evaporation. The compressive strength of soil for backfilling reached 4.91 MPa and improved the wind erosion resistance of the consolidation layer, effectively resisting wind damage. At a construction site, the waterborne polymer was sprayed on soil for backfilling, and the concentration of PM10 was reduced by 67.41%, confirming the effectiveness for large-scale utilization.
By analyzing the problems in the process of restoration of Gaussian blurred images in strong noise,a pre-filter that could pretreat strong noise effectively is designed based on the Wiener filter,and the effects of the pre-filter are verified by computer simulation.The results show that the pre-filter performs very well and is an effective method for restoration of image
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