Expansion of the F127-templated mesostructure in aerosol-generated particles by using polypropylene glycol as a swelling agentVise andre og tillknytning
2008 (engelsk)Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 113, s. 1-13Artikkel i tidsskrift (Fagfellevurdert)
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.
sted, utgiver, år, opplag, sider
2008. Vol. 113, s. 1-13
Emneord [en]
Polypropylene glycol, expanded pores, swelling agent, mesoporous particles, F127, aerosol, nitrogen adsorption, wall density, geometrical models, NLDFT, BdB-FHH, KJS
HSV kategori
Identifikatorer
URN: urn:nbn:se:ri:diva-27314OAI: oai:DiVA.org:ri-27314DiVA, id: diva2:1054318
Merknad
A1899
2016-12-082016-12-082020-12-01bibliografisk kontrollert