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Expansion of the F127-templated mesostructure in aerosolgeneratedparticles by using polypropylene glycol as a swelling agent
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry. (Ytkemi)
YKI, Ytkemiska Institutet. (Ytkemi)
2008 (English)In: Microporous and Mesoporous Materials, ISSN 1387-1811, Vol. 113, 1-13 p.Article in journal (Refereed) Published
Abstract [en]

Expansion of the mesostructure in aerosol-generated particles was performed through incorporation of polypropylene glycol (PPG), a non-volatile swelling agent. TEOS was used as silica source and the Pluronic block copolymer, F127, as template. The ratio of TEOS to F127 was kept constant during synthesis, while varying the weight ratio of PPG to F127 systematically. The impact of the PPG on the expansion of the structure was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and nitrogen adsorption. Different methods were used to calculate the pore size distributions, the BJH, the BdB-FHH, the KJS and the NLDFT method. Simple geometrical models of the expansion were derived to interpret the experimental data and establish their accuracy. Experimental data showed a roughly linear expansion of the unit cell and pore size, consistent with that expected by modelling the swelling of a hexagonal (p6mm) structure assuming constant wall thickness. The expansion is increasing as a function of increasing PPG/F127 ratio by about 25 Å. An expression of the density of the silica wall was calculated from the models resulting in a density of 1.95 ± 0.2 g/cm3. At a PPG/F127 ratio of approximately 0.31, the p6mm structure (found at lower PPG/F127 ratios) transforms to a microemulsion-templated foam structure. At an even higher PPG/F127 ratio (0.63–1.56), phase separation of the oil from the swollen template occurred, yielding a two-phase system of coexisting foam and large vesicles.

Place, publisher, year, edition, pages
2008. Vol. 113, 1-13 p.
Keyword [en]
Polypropylene glycol; Expanded pores; Swelling agent; Mesoporous particles; F127; Aerosol; Nitrogen adsorption; Geometrical models; NLDFT; BdB-FHH; KJS
National Category
Physical Chemistry
URN: urn:nbn:se:kth:diva-10102DOI: 10.1016/j.micromeso.2007.10.045ISI: 000257362100002OAI: diva2:208639
QC 20100811Available from: 2009-03-19 Created: 2009-03-19 Last updated: 2012-03-20Bibliographically 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.
TRITA-CHE-Report, ISSN 1654-1081 ; 2009:8
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
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)

QC 20100811

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

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