Periodic with amorphous wall structure

Periodic Mesoporous Organosilicas with Amorphous Wall Structure... 

Control over the material s shape at the nanoscale enables further control over reactants access to the dopant, and ultimately affords a potent means of controlling function which is analogous to that parsimoniously employed by Nature to synthesize materials with myriad function with a surprisingly low number of material s building blocks. A nice illustration is offered by the extrusion catalytic polymerization of ethylene within the hexagonal channels of MCM-41 mesoporous silica doped with catalyst titanocene.36 The structure is made of amorphous silica walls spatially arranged into periodic arrays with high surface area (up to 1400 m2g 1) and mesopore volume >0.7 mLg-1. In this case, restricted conformation dictates polymerization the pore diameter... 

X-ray diffraction measurements and structural calculations on murein [22-25] and pseudomurein [26-28] have revealed several common structural features in both polymers. Murein and pseudomurein sacculi possess a density of p= 1. 39-1.46g/cm which is characteristic of highly ordered material. A much lower density, in the range of p= 1.24-1.32g/cm is to be expected for amorphous polymers [26]. X-ray diffraction showed diffuse Debye-Scherer rings with Bragg periodicities of about 0.45 nm and 0.94 nm in the planes and of 4.3-4.5nm vertically to the planes of both types of cell walls. These data have been interpreted in two different ways ... 

Microporous carbons have been prepared as inverse replicas of zeolites. " Zeolite-templated carbons (ZTCs) are prepared by filling the micropores of zeolites, snch as zeolite Y and X13, with a suitable carbon source, for example, furfuryl alcohol, followed by carbonization of composites and dissolution of the siliceous framework. As a result of the well-defined three-dimensional (3D) crystal structure of most starting zeolite materials, ZTCs exhibit amorphous carbon walls having a periodic arrangement of micropores. The ZTCs exhibit the same periodicity as the starting microporous templates in the range of 1.0-2.0 nm, as shown in Figure... 

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