Mesoporous SiO2 Nanoparticles Research Articles

Towards long-term colloidal stability of silica-based nanocarriers for hydrophobic molecules: beyond the Stöber method

The highly uniform micro- and mesoporous SiO(2) nanoparticles (40-70 nm) are hierarchically functionalized with antagonistic groups: hydrophobic (phenyl) on the internal pores and hydrophilic (methyl-phosphonate) on the external surface. Considering the large hydrophobic internal coating and the long-term colloidal stability, these systems are suitable nanocarriers by using the host-guest approach.

Structural and magnetic properties of mesoporous SiO2 nanoparticles impregnated with iron oxide or cobalt-iron oxide nanocrystals

Magnetic nanocomposites of FeOx@SiO2 and CoFe2O4@SiO2 were prepared via a wet-impregnation route using mesoporous silica nanoparticles as a support matrix. The small pores in the matrix were exploited as nanocavities for controlled growth of the embedded oxide phase, initially examined by introducing different wt% loadings of FeOx in four different samples and sequentially treating them under oxidising and reducing conditions. Comparative examination of the morphological and structural properties of the FeOx@SiO2 compositions shows that a 17 wt% (nominal) loading of the oxide phase, a mixture of Fe3O4 (magnetite) and γ-Fe2O3 (maghemite), is fully embedded within the pores. The 60–70 nm dimensions of the SiO2 nanoparticles are visible in TEM micrographs which reveal a spheroidal shape. TEM also shows a ca. 3 nm size for the crystalline oxide particles embedded within, which agrees with the pore sizes estimated through porosimetric analysis. The measurements for field-cooled (FC), zero-field-cooled (ZFC) magnetizations, and hysteresis loops in the temperature range of 3 K to 300 K reveal that an enhancement in the density of magnetization is obtained for the 17 wt% FeOx@SiO2 sample following reductive thermal treatment. A CoFe2O4@SiO2 nanocomposite prepared with a nominal 14 wt% oxide shows comparable structure and morphology to the 17 wt% FeOx@SiO2 sample, yet superior magnetic properties. The higher density of magnetization in CoFe2O4@SiO2 is attributed to its 40% content of magnetic material in the crystalline phase, versus 6–8% in FeOx@SiO2. Efficient surface functionalisation with APTES, monitored by DRIFT-IR, implies that the magnetic nanocomposites could be used in bio-labelling applications. Data derived from Raman spectroscopy, N2 adsorption/desorption measurements, and TGA are also used to characterise the nanocomposite materials.

Sulfonated poly(arylene ether sulfone) thin-film composite reverse osmosis membrane containing SiO2nano-particles

Novel thin-film nano-composite membranes containing SiO2 nano-particles are successfully fabricated via interfacial polymerization with trimesoyl chloride (TMC), sulfonated poly(arylene ether sulfone) copolymers and silica (SiO2) nano-particles on a polysulfone (PS) support membrane. Sulfonated poly(arylene ether sulfone) copolymers containing carboxylic and amino groups (cPES) are successfully prepared via direct polymerization as novel thin-film composite (TFC) reverse osmosis (RO) membrane material. Mesoporous SiO2 nano-particles are also successfully synthesized. The synthesized cPES copolymers, SiO2 nano-particles and fabricated cPES membranes are characterized by nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). The incorporation of SiO2 nanoparticles were confirmed by energy dispersive X-ray spectroscopy (EDX). Moreover, the effects of different fabrication conditions on performance are investigated. The cPES membr...