Preparation and Properties of Porous Microspheres Made from Borate Glass
Dysprosium lithium-borate glass microspheres and particles, ranging from 45 to 150 m in diameter, were reacted with a 0.25M phosphate solution at 37°C, whose pH was either 3 or 8.8. The glass reacted nonuniformly and was converted into a porous, amorphous, hydrated, dysprosium phosphate reaction product. The amorphous product had the same volume and shape (pseudomorphic) as the unreacted glass, and could be dried without cracking. After heating at 300°C for 1 h, the amorphous reaction product had a specific surface area of 200 m2/g, a pore size of 30 nm, and nominal crushing strength of 10 MPa. when the reaction product was heated to 600°C for 15 min, the specific surface area decreased to 90 m2/g and the nominal crushing strength increased to 35 MPa. Heating above 615°C converted the amorphous dysprosium phosphate product into crystalline DyPO4, which contained open porosity until heated above 800°C for 15 min. Highly porous materials of different chemical composition can be prepared by chemically reacting a borate-based glass with an aqueous solution at low-temperature (<100°C). These highly porous materials are easy to process, and are considered candidates for controlled drug delivery, catalysis, chromatographic separation, filtration, and as bioactive materials.
S. D. Conzone and D. E. Day, "Preparation and Properties of Porous Microspheres Made from Borate Glass," Journal of Biomedical Materials Research - Part A, John Wiley & Sons, Feb 2008.
The definitive version is available at http://dx.doi.org/10.1002/jbm.a.31883
Materials Science and Engineering
Keywords and Phrases
Drug Delivery; Sol Gel; Specific Surface Area; Catalysis; Porous materials
Article - Journal
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