Preparation of aqueous colloidal mesostructured and mesoporous silica nanoparticles with controlled particle size in a very wide range from 20 nm to 700 nm

Abstract

Particle size control of colloidal mesoporous silica nanoparticles (CMPS) in a very wide range is quite significant for the design of CMPS toward various applications, such as catalysis and drug delivery. Various types of CMPS and their precursors (colloidal mesostructured silica nanoparticles (CMSS)) with different particle sizes (ca. 20-700 nm) were newly prepared from tetraalkoxysilanes with different alkoxy groups (Si(OR)4, R = Me, Et, Pr, and Bu) in the presence of alcohols (R'OH, R' = Me, Et, Pr, and Bu) as additives. CMSS with larger particle size were obtained by using tetrabutoxysilane (TBOS) and by increasing the amount of BuOH, which is explained by both the difference in the hydrolysis rates of tetraalkoxysilanes themselves and the effect of added alcohols on the hydrolysis rates of tetraalkoxysilanes. Larger amounts of alcohols with longer alkyl chains decrease the hydrolysis rates of tetraalkoxysilanes and the subsequent formation rates of silica species. Thus, the preferential particle growth of CMSS to nucleation occurs, and larger CMSS are formed. Highly dispersed CMPS were prepared by the removal of surfactants of CMSS by dialysis which can lead to the preparation of CMPS without aggregation. Therefore, the particle size control through the tuning of the hydrolysis rate of tetraalkoxysilanes can be conducted by a one-pot and easy approach. Even larger CMPS (ca. 700 nm in size) show relatively high dispersibility. This dispersibility will surely contribute to the design of materials both retaining nanoscale characteristics and avoiding various nanorisks.

Monodispersed mesoporous silica nanospheres based on pyridinium ionic liquids

“…Significant weight loss occurred between 250 and 500 °C and this is due to removal of pyridinium ILs templates (Fig. S3) [19,40].…”

“…TG curves (Fig. S2) shows significant weight loss occurred between 250 and 500 °C which due the removal pyridinium ILs templates [19,40]. The porosity of the synthesized MNSs was further examined by N 2 adsorption-desorption and all MNSs sample exhibit type IV isotherm which is the norm for mesoporous materials (Fig.…”

“…Bein et al reported on the use of triethanolamine (TEA) as the base for the reaction as it would act as the catalyst and encapsulator in developing monodispersed MSNs [17]. In the recent years, Yamada et al utilizes TEA in generating monodispersed MSNs while studying the effects of template amount, presence of alcohol, types of alcohols and alkyl chain length of the template on the synthesized MSNs [18][19][20]. All these researches used the common template which is cetyltrimethylammonium bromide or chloride (CTAB/CTACl).…”

Controlled release and intracellular protein delivery from mesoporous silica nanoparticles

“…[34]. Additionally, alcohols with long alkyl chains have been shown to affect MSN particle size by altering the tetraalkylsilicate hydrolysis kinetics [35]. The ratio of silica precursor to surfactant is also crucial for soft templated MSN, with ratios lower than 0.13 preventing the pores from extending through the entire particle [36].…”

Colloidal Mesoporous Silica Nanoparticles

“…116,117 We also investigated the effect of alcohols on the size control of colloidal MSNs, and found that the addition of a hydrophobic alcohol leads to the enlargement of MSNs (Figure 11). 118 These methods are very useful for the precise control of the diameter of MSNs because only the hydrolysis rate can be tuned without drastically changing the condensation rate.…”