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Pore Surface (pore + surface)

Distribution by Scientific Domains

Polymers and Materials Science	38%
Chemistry	38%

Selected Abstracts

A Microporous Metal,Organic Framework with Immobilized ,OH Functional Groups within the Pore Surfaces for Selective Gas Sorption

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 24 2010
Zhenxia Chen
Abstract A new two-dimensional microporous metal,organic framework Cu(BDC-OH)(H2O)·0.5DEF [abbreviation: Cu(BDC-OH); H2BDC-OH = 2-hydroxybenzene-1,4-dicarboxylic acid; DEF = diethylformamide] with functional OH groups on the pore surfaces was solvothermally synthesized and structurally characterized. The activated Cu(BDC-OH) exhibits a moderate Langmuir surface of 584 m2,g,1, a pore volume of 0.214 cm3,g,1, and C2H2/CH4 and CO2/CH4 selectivity of 6.7 and 9.3, respectively, at 296 K, thereby highlighting the promise for its application in gas separation. [source]

Scaling analysis of water retention curves for unsaturated sandy loam soils by using fractal geometry

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2010
C. Fallico
Fractal geometry was deployed to analyse water retention curves (WRC). The three models used to estimate the curves were the general pore-solid fractal (PSF) model and two specific cases of the PSF model: the Tyler & Wheatcraft (TW) and the Rieu & Sposito (RS) models. The study was conducted on 30 undisturbed, sandy loam soil samples taken from a field and subjected to laboratory analysis. The fractal dimension, a non-variable scale factor characterizing each water retention model proposed, was estimated by direct scaling. The method for determining the fractal dimension proposed here entails limiting the analysis to the interval between an upper and lower pressure head cut-off on a log-log plot, and defining the dimension itself as the straight regression line that interpolates the points in the interval with the largest coefficient of determination, R2. The scale relative to the cut-off interval used to determine the fractal behaviour in each model used is presented. Furthermore, a second range of pressure head values was analysed to approximate the fractal dimension of the pore surface. The PSF model exhibited greater spatial variation than the TW or RS models for the parameter values typical of a sandy loam soil. An indication of the variability of the fractal dimension across the entire area studied is also provided. [source]

Organically Functionalized Mesoporous Silica by Co-structure-Directing Route

ADVANCED FUNCTIONAL MATERIALS, Issue 17 2010
Chuanbo Gao
Abstract This article provides a brief overview of functional mesoporous silica materials synthesized by the co-structure-directing route, which is distinct from conventional synthesis strategies. In these systems, organosilane serves as the co-structure-directing agent (CSDA), which provides critical interactions between the template and organic part of the organosilane to form mesostructures, thus retaining the organic groups on the pore surface after removal of the template by extraction. i) The formation of anionic-surfactant-templated mesoporous silicas (AMSs) has been achieved by the co-structure-directing route, which leads to a variety of mesostructures, porous properties and morphologies. ii) Other co-structure-directing systems for synthesizing mesoporous silicas have also been achieved, including systems using cationic surfactants and non-surfactants, and systems using DNA for constructing nanofibers and DNA,silica liquid crystalline complexes. iii) Evidence for the regular arrangement of functional groups on the pore surface resulted from the co-structure-directing effect has been discussed. Also included is a brief description of the application, future requirements, and trends in the development of mesoporous materials by the co-structure-directing route. [source]

Preparation and HPLC applications of rigid macroporous organic polymer monoliths

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 10-11 2004
Frantisek Svec
Abstract Rigid porous polymer monoliths are a new class of materials that emerged in the early 1990s. These monolithic materials are typically prepared using a simple molding process carried out within the confines of a closed mold. For example, polymerization of a mixture comprising monomers, free-radical initiator, and porogenic solvent affords macroporous materials with large through-pores that enable applications in a rapid flow-through mode. The versatility of the preparation technique is demonstrated by its use with hydrophobic, hydrophilic, ionizable, and zwitterionic monomers. Several system variables can be used to control the porous properties of the monolith over a broad range and to mediate the hydrodynamic properties of the monolithic devices. A variety of methods such as direct copolymerization of functional monomers, chemical modification of reactive groups, and grafting of pore surface with selected polymer chains is available for the control of surface chemistry. Since all the mobile phase must flow through the monolith, the convection considerably accelerates mass transport within the molded material, and the monolithic devices perform well, even at very high flow rates. The applications of polymeric monolithic materials are demonstrated mostly on the separations in the HPLC mode, although CEC, gas chromatography, enzyme immobilization, molecular recognition, advanced detection systems, and microfluidic devices are also mentioned. [source]

Effect of Surface Modification on the Synthesis of Pore-Filling Polymeric Monoliths in Microfiltration Membranes Made from Poly(propylene) and Poly(ethylene terephthalate)

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 3 2007
Abdus Salam
Abstract The effect of pre-modification on the interaction of macroporous substrates (membranes) with mainly micro- and mesoporous polymer monoliths has been studied. Bulk, porous polymer monoliths were synthesized to optimize the synthesis conditions and their pore morphology, and the data were used as benchmark for this study. Pre-modification of the entire pore surface of PP microfiltration membranes and PET track-etched membranes by UV-initiated grafting with PEGMA was performed using well-established methods, including coating with the photo-initiator, benzophenone. Subsequently, these membranes were functionalized by filling the pores with porous polymer monoliths from MAA and EDMA and compared with membranes that had been functionalized without the pre-modification step. The materials were characterized mainly by the degree of grafting, SEM and by the gas-adsorption-isotherm method. The DG values, after composite-membrane preparation under identical conditions, were not influenced by the pre-modification. However, it could be clearly seen from the SEM images that the pre-modification step prevents the formation of voids at the monolith-membrane pore interface. Larger specific surface area and pore volume values for composite membranes, prepared after pre-modification, fully support the SEM results. Especially large differences in pore structure between the two different composite membranes were found in the mesopore range. The results of this study indicate that it is possible to prepare porous, composite membranes where the trans-membrane transport is exclusively controlled by the pore and surface structure of a functional polymeric monolith, for example, made from a molecularly-imprinted polymer. [source]

Physico-Mechanical Properties, Odor and VOC Emission of Bio-Flour-Filled Poly(propylene) Bio-Composites with Different Volcanic Pozzolan Contents

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2006
Hee-Soo Kim
Abstract Summary: This study investigated the physico-mechanical properties, odor and VOC emission of bio-flour filled PP bio-composites with different pozzolan contents. On increasing the pozzolan content, the tensile and flexural strengths of the bio-composites were not significantly changed, whereas the impact strength and water absorption increased slightly and the odor intensity decreased due to the absorption of thermal degradation gases of PP and bio-flour at the pore surface of the pozzolan. The VOC emission of the bio-composites, analyzed by GC-MSD, was mainly due to PP oxidation and the thermal degradation of bio-flour during the extrusion process at high manufacturing temperatures. With increased pozzolan content, other organic compounds of the bio-composites were not significantly changed, but the toluene emission of the bio-composites was decreased. SEM and SEM/EDX mapping techniques were employed to investigate the porous form and the pozzolan distribution in the bio-composites. From these results, we concluded that the addition of pozzolan in the bio-composites was an effective method for reducing their odor and VOC emission without any reduction in mechanical properties. SEM micrograph of pozzolan (10,000×). [source]

Gravimetric method to find internal surface of macroporous silicon membranes

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2007
A. A. Nechitailov
Abstract A simple method to evaluate the internal surface area, porosity, pore diameter and pore density of macroporous silicon membranes has been proposed and tested. The porosity p is obtained from the mass loss under anodizing, and the surface area per unit volume Sv is determined from the mass of SiO2 formed on the pore surface as a result of thermal oxidation. The average pore diameter d and pore density N can be easily calculated from the obtained Sv and p. Experimental verification of d and N was performed by means of SEM and optical microscope images; Sv was checked by BET technique. Surface area and porosity on the resistivity of initial n-Si in the range , = 3,25 Ohm · cm have been studied for the samples with regular and self-organized macropore "lattices". The obtained values are within the limits p = 27,50%, Sv = 2800,6000 cm2/cm3, d = 1.9,6.5 ,m, N = 1.4,10 × 106 cm,2, and in a good agreement with the data of microscopic characterization. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Investigations on porous silicon as electrode material in electrochemical capacitors

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2007
S. Desplobain
Abstract In this study, we have demonstrated the possibility of using macroporous silicon electrodes in electrochemical capacitors. Macroporous silicon was used to increase the surface exchange between pore surface and electrolyte. The inherent resistivity of the porous silicon can be reduced through the use of subsequent doping and metallization processes of the macropore surface. A systematic study of the electrolyte concentration and the porous silicon depth influences was also performed. A unit cell capacitance value of 320 µF/cm2 was obtained with doped and metallized p-type macroporous silicon electrodes. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

A Microporous Metal,Organic Framework with Immobilized ,OH Functional Groups within the Pore Surfaces for Selective Gas Sorption

Dual-Growth-Factor-Releasing PCL Scaffolds for Chondrogenesis of Adipose-Tissue-Derived Mesenchymal Stem Cells,

ADVANCED ENGINEERING MATERIALS, Issue 1-2 2010
Sung Mook Lim
Polycaprolactone/Pluronic F127 porous scaffolds are prepared using a modified melt-molding particulate-leaching method. The scaffolds are highly porous (about 90% porosity) and have open-cellular pore structures. Growth factors (TGF- ,2, BMP-7 or dual TGF- ,2/BMP-7) can be easily immobilized on the pore surfaces of the PCL/F127 scaffolds via binding with heparin. The growth-factor-immobilized scaffolds can induce the chondrogenesis of ATMSCs seeded onto them. Using TGF-,2 and BMP-7 growth factors together leads to a better chondrogenic differentiation behavior than using single-growth-factor immobilized scaffolds. [source]

Encoded Porous Beads for Label-Free Multiplex Detection of Tumor Markers

ADVANCED MATERIALS, Issue 5 2009
Yuanjin Zhao
Inverse-opaline photonic beads are used as the elements of a suspension array for label-free multiplex immunoassays. As in the case of tumor-marker detection, specific binding of tumor markers on the pore surfaces of the beads results in a shift in the diffraction-peak position, which can be used for quantitatively estimating the amount of bound tumor marker. [source]

Critical behavior in quenched random structures: Mean-field lattice-gas approach

AICHE JOURNAL, Issue 2 2001
S. De
A new mean-field equation-of-state model is proposed for predicting the critical behavior of fluids confined in porous, random structures. The approach is based on a lattice-gas formalism and incorporates effects of both fluid confinement and energetically heterogeneous interactions between fluid molecules and pore surfaces. The model was used to predict a variety of thermodynamic properties in these systems, including the dependence of the confined fluid's critical properties on the porosity and relative strength of fluid,fluid and fluid,pore interaction energies. The study of suface-energy heterogeneities show that they significantly affect the critical temperature of the confined fluid, at a given porosity, compared to the uniform energy case. Comparison of the model performance with both grand canonical Monte Carlo simulation results and a set of adsorption data in a silica gel suggest that the approach taken here provides a useful analytic method for calculating physical properties in complex systems of this kind. [source]

Chemical surface passivation of 3C-SiC nanocrystals: A first-principle study

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 13 2010
A. Trejo
Abstract The effect of the chemical surface passivation, with hydrogen atoms, on the energy band gap of porous cubic silicon carbide (PSiC) was investigated. The pores are modeled by means of the supercell technique, in which columns of Si and/or C atoms are removed along the [001] direction. Within this supercell model, morphology effects can be analyzed in detail. The electronic band structure is performed using the density functional theory based on the generalized gradient approximation. Two types of pores are studied: C-rich and Si-rich pores surface. The enlargement of energy band gap is greater in the C-rich than Si-rich pores surface. This supercell model emphasizes the interconnection between 3C-SiC nanocrystals, delocalizing the electronic states. However, the results show a clear quantum confinement signature, which is contrasted with that of nanowire systems. The calculation shows a significant response to changes in surface passivation with hydrogen. The chemical tuning of the band gap opens the possibility plenty applications in nanotechnology. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem 110:2455,2461, 2010 [source]