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AFM-Porosimetry: Density and pore volume measurements ofparticulate materials
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry (closed 20081231). (Ytkemi)
KTH, School of Chemical Science and Engineering (CHE), Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry.ORCID iD: 0000-0002-8935-8070
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2008 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 24, 7024-7030 p.Article in journal (Refereed) Published
Abstract [en]

We introduced the novel technique of AFM-porosimetry and applied it to measure the total pore volume of porous particles with a spherical geometry. The methodology is based on using an atomic force microscope as a balance to measure masses of individual particles. Several particles within the same batch were measured, and by plotting particle mass versus particle volume, the bulk density of the sample can be extracted from the slope of the linear fit. The pore volume is then calculated from the densities of the bulk and matrix materials, respectively. In contrast to nitrogen sorption and mercury porosimetry, this method is capable of measuring the total pore volume regardless of pore size distribution and pore connectivity. In this study, three porous samples were investigated by AFM-porosimetry: one ordered mesoporous sample and two disordered foam structures. All samples were based on a matrix of amorphous silica templated by a block copolymer, Pluronic F127, swollen to various degrees with poly(propylene glycol). In addition, the density of silica spheres without a template was measured by two independent techniques: AFM and the Archimedes principle.

Place, publisher, year, edition, pages
2008. Vol. 24, 7024-7030 p.
Keyword [en]
atomic-force microscope; size-exclusion chromatography; nmr cryoporometry; adsorption hysteresis; cantilever sensors; functional theory; gas-adsorption; nitrogen; mcm-41; liquid
National Category
Physical Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-10103DOI: 10.1021/la800260hISI: 000257101100086Scopus ID: 2-s2.0-47349113900OAI: oai:DiVA.org:kth-10103DiVA: diva2:208652
Note

QC 20100811

Available from: 2009-03-19 Created: 2009-03-19 Last updated: 2016-12-19Bibliographically approved
In thesis
1. Mesostructured particulate silica materials with tunable pore size: Synthesis, characterization and applications
Open this publication in new window or tab >>Mesostructured particulate silica materials with tunable pore size: Synthesis, characterization and applications
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Colloidal assemblies of surfactants and polymers in aqueous solutions have been used by human mankind for hundreds of years and they are of great importance in many of our technological processes, such as fabrication of soap and papermaking. Less than two decades ago the idea of using colloidal assemblies as templates of inorganic materials was borne. A new population of materials, referred to as surfactant templated materials, took form. These materials showed extraordinary properties such as monodisperse pore size distribution, large surface areas and pore volumes.

 

The main focus of this thesis has been on synthesis and functionalisation of spherical mesostructured silica particulate materials. In the first part of the work, mesostructured materials with expanded pores have been produced using a well established aerosol-based method as well as the newly developed emulsion and solvent evaporation (ESE) method. Increase in pore size was realized through using Pluronic block copolymer F127 together with a swelling agent poly(propylene glycol) as template. The influence of the swelling agent on pore size expansion was shown to have a roughly linear relationship. Furthermore, the impact of synthesis parameters on internal and exterior morphology has been investigated. Accessibility of the internal pore space, as well as the external surface roughness were shown to be highly dependent on synthesis temperature. Additionally, a very interesting well ordered 3D closed packed (P63/mmc) material was produced using the ionic surfactant C16TAB as template in the ESE method.

 

In the second part of the thesis work, mesoporous spheres with large pore size, having either hydrophilic or hydrophobic surface properties, were used as carriers of an enzyme, lipase. The enzymatic activity of lipase was increased onto the hydrophobic surface, compared to lipase immobilized into the hydrophilic support as well as for lipase free in solution. This effect was probably due to a combination of enhanced hydrophobic interactions preventing denaturation of the enzyme and interfacial activation of the enzyme.  This study generated an inorganic carrier material that is a promising candidate for biocatalysis applications. Additionally, mesoporous spheres were used as carriers of a model drug, Ibuprofen, to study the effect of polyelectrolyte multilayers on release properties. However, these layers were shown impermeable independent on pH and the substance was only released from uncoated particles.

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. 70 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2009:8
Keyword
Mesoporous materials, aersol-based process, emulsion-based process, biocatalysis, sustained release, 3D hexagonal, 2D hexagonal, powder, spherical particles, liquid crystalline phases, AFM-porosimetry, Pluronic
National Category
Other Basic Medicine
Identifiers
urn:nbn:se:kth:diva-10089 (URN)978-91-7415-243-2 (ISBN)
Public defence
2009-04-03, E2, Lindstedsvägen 3, Stockholm, 10:00 (English)
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Supervisors
Note

QC 20100811

Available from: 2009-03-19 Created: 2009-03-11 Last updated: 2014-11-03Bibliographically approved

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Publisher's full textScopushttp://pubs.acs.org/doi/abs/10.1021/la800260h

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