			Home About us Contact

Microporous Structure (microporou + structure)

Distribution by Scientific Domains

Polymers and Materials Science	75%

Selected Abstracts

Polydisperse Spindle-Shaped ZnO Particles with Their Packing Micropores in the Photoanode for Highly Efficient Quasi-Solid Dye-Sensitized Solar Cells

ADVANCED FUNCTIONAL MATERIALS, Issue 3 2010
Yantao Shi
Abstract In this paper, a novel hierarchically structured ZnO photoanode for use in quasi-solid state dye-sensitized solar cells (DSCs) is presented. The film is composed of polydisperse spindle-shaped ZnO particles that are prepared through direct precipitation of zinc acetate in aqueous solution. Without additional pore-forming agents, the microporous structure is well constructed through the packing of polydisperse ZnO particles. In the film, small ZnO particles are able to improve interparticle connectivity and offer a large internal surface area for sufficient dye-adsorption; on the other hand, particles of larger size can enhance the occurrence of light-scattering and introduce micropores for the permeation of quasi-solid state electrolytes. Meanwhile, morphologies, particle size, and specific areas of the products are controlled by altering the reactant concentration and synthetic temperature. Combined with a highly viscous polymer gel electrolyte, a device based on this ZnO photoanode shows high conversion efficiencies, 4.0% and 7.0%, under 100 and 30,mW cm,2 illumination, respectively. Finally, the unsealed device is demonstrated to remain above 90% of its initial conversion efficiency after 7 days, showing excellent stability. [source]

A Series of Novel Organically Templated Germanium Antimony Sulfides

CHEMISTRY - AN ASIAN JOURNAL, Issue 8 2010
Mei-Ling Feng Dr.
Abstract A series of novel organically templated germanium antimony sulfides have been solvothermally synthesized and structurally, thermally, and optically characterized. The compound [Me2NH2]6[(Ge2Sb2S7)(Ge4S10)] (1) features two distinct tetranuclear [Ge2Sb2S7]2, and [Ge4S10]4, isolated clusters. The compound [(Me)2NH2][DabcoH]2[Ge2Sb3S10] (2) (Dabco=triethylenediamine) features a 1D-[Ge2Sb3S10]n3n, ribbon constructed with two [GeSbS5]n3n, chains bridged by Sb3+ ion in , -SbS4 configuration. Compounds [M(en)3][GeSb2S6] (M=Ni (3), Co (4) en=ethylenediamine) feature the unique 2D grid layer structures of [GeSb2S6]n2n,. The compound [(Me)2NH2]2[GeSb2S6] (5) previously reported by us features a 3D chiral microporous structure with the chiral channels. The optical absorption spectra indicate that all the compounds are wide bandgap semiconductors. Thermal stabilities of these compounds have been investigated by thermogravimetric analyses (TGA). [source]

Bifurcated Mechanical Behavior of Deformed Periodic Porous Solids

ADVANCED FUNCTIONAL MATERIALS, Issue 9 2009
Srikanth Singamaneni
Abstract The transformation of periodic microporous structures fabricated by interference lithography followed by their freezing below glass transition is described. Periodic porous microstructures subjected to internal compressive stresses can undergo sudden structural transformation at a critical strain. The pattern transformation of collapsed pores is caused by the stresses originated during the polymerization of acrylic acid (rubbery component) inside of cylindrical pores and the subsequent solvent evaporation in the organized microporous structure. By confining the polymerization of acrylic acid to localized porous areas complex microscopic periodic structures can be obtained. The control over the mechanical instabilities in periodic porous solids at a sub-micron scale demonstrated here suggests the potential mechanical tunability of photonic, transport, adhesive, and phononic properties of such periodic porous solids. [source]

Melt processed microporous films from compatibilized immiscible blends with potential as membranes

POLYMER ENGINEERING & SCIENCE, Issue 4 2002
M. Xanthos
Microporous flat films with potential as membranes were produced via melt processing and post-extrusion drawing from immiscible polypropylene/polystyrene blends containing a compatibilizing copolymer. The blends were first compounded in a co-rotating twin-screw extruder and subsequently extruded through a sheet die to obtain the precursor films. These were uniaxially drawn (100%,500%) with respect to the original dimensions to induce porosity and then post-treated at elevated temperatures to stabilize the resultant structure, which consisted of uniform microcracks in the order of a few nanometers in width. The effects of blend composition and extrusion process parameters on surface and cross-sectional porosity and solvent permeability of the prepared films are presented and related to specific microstructural features of the films before and after drawing. Finite element modeling of the stretching operation in the solid state yielded a successful interpretation of the blend response to uniaxial tension that resulted in microcrack formation. Comparison of some of the novel microporous structures of this work with commercial membranes prepared by solvent-based phase inversion processes suggests comparable pore size and porosity ranges, with narrower pore size distribution. [source]