engleski

Systematic study of reaction conditions for size controlled synthesis of silica nanoparticles

Silica nanoparticles (SNPs) are one of the most widely used and studied nanoparticles. Their advantages include simple synthesis, biocompatibility, stability, simple chemical or biochemical surface modification. Many scientific studies reported optimization of conditions for size controlled synthesis of SNPs, yet laboratory scale production of monodisperse SNPs with desired size in the range of 3–200 nm remains challenging. In this work we have performed a systematic examination of the influence of 4 main parameters on the size in synthesis SNPs ; temperature, concentration of tetraethoxysilane (TEOS), ammonia and water. The synthesis was performed based on the work of Stöber, Fink and Bohn. For all experiments we have used vials with the same size, same magnetic stirring bars, constant stirring rate and ethanol as a solvent. TEOS was freshly distilled and the concentration of ammonium hydroxide was determined with titration, prior to all experiments. The series of experiments was performed by changing only one of the parameters. The concentration of TEOS was varied from 0.01-0.26 M, ammonia as a catalyst 0.097-0.291 M and water 2-5 M. Temperatures were in the range of 25-55°C. At low TEOS concentrations there was a very low yield of SNPs, for this reason the concentration was set to 0.26 M for all other experiments. A liner correlation between the size and temperature was found, as well as for size and water concentration. This liner correlation remained for three different ammonia concentrations, but different SNPs size ranges. After statistical analysis of experimental data we have found that the size of the SNPs can be engineered in the 5-200 nm range with good reproducibility and confidence interval by changing one of the main parameters of synthesis. Best results can be obtained by altering the concentration of ammonia or temperature.

silica nanoparticles ; TEOS ; ammonia

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