A Universal Approach for the Reversible Phase Transfer of Hydrophilic Nanoparticles

Abstract

The ability to engineer the surface properties of magnetic nanoparticles is important for their various applications, as numerous physical and chemical properties of nanoscale materials are seriously affected by the chemical constitution of their surfaces. For some specific applications, nanoparticles need to be transferred from a polar to a nonpolar environment (or vice versa) after synthesis. In this work we have developed a universal method for the phase transfer of magnetic nanoparticles that preserves their shape and size. Octadecyltrimethoxysilane was used to cap the surfaces of the aqueous magnetic nanoparticles, thereby allowing their transfer into nonpolar solution. The resulting hydrophobic magnetic nanoparticles were transferred back into aqueous solution by subsequently covering them with an egg-PC lipid monolayer. The superparamagnetic properties of the particles were retained after the phase transfer. The maximum transfer yields are dependent on their particle size with a maximum value of 93.16 ± 4.75% for magnetic nanoparticles with a diameter of 100 nm. The lipid-modified magnetic particles were stable over 1 week, and thus they have potential applications in the field of biomedicine. This work also provides a facile strategy for the controllable engineering of the surface properties of nanoparticles.

Decoratable hybrid-film-patch stabilized Pickering emulsions and their catalytic applications

“…One is the silanization of CNTs and Fe3O4 make them more hydrophobic, which is good for PE stability. Due to the presence of hydroxyl groups on CNTs and Fe3O4 NPs, they are easily modified with ODTS [33]. The other is ODTS molecules hydrolyze at the oil/water interface and then forming polymers.…”

“…0.9 mg CNTs and 0.1 mg Fe3O4 were added into 1.0 mL hexane containing 10 μL ODTS, followed by 15 minute sonication. [33]. The silanization of CNTs renders CNTs more hydrophobic, which is good for hybrid film formation.…”

Assembly of Janus complex with low-cost and salt rejection for solar-thermal water evaporation

“…Then, the mixed liquid was filtered and repeatedly washed to cleanness, and then dried at 150 ° C for 4 hours in a forced air oven [48], the obtained sample was labelled as OCNTs. In a typical assembly process, OCNTs was first modified by ODTS, 9 mg of OCNTs was added to 10 mL of hexane containing 100 μL of ODTS, and sonicated for 15 min [49]. Then the mixture was mixed with a volume of PDDA aqueous solution (20 μL mL -1 ) and vortex for 1 minute.…”

Dispersing hydrophilic nanoparticles in nonaqueous solvents with superior long-term stability

“…21 Phase transfer of hydrophilic nanoparticles to hydrophobic solvents has mainly been accomplished through ligand exchange processes to modify the surface wettability. [21][22][23][24] Taking metal nanoparticles as an example, many ligand-exchange techniques have been developed. [25][26][27] Underwood and Melvaney pioneered the study on the phase transfer of gold nanoparticles from water to an organic solvent such as butyl acetate with a co-polymer based 'comb stabilizer'.…”

“…[28][29][30][31][32] Despite recent advances in the phase transfer of nanoparticles, there are still several general concerns regarding ligand exchange methods. 23,24,33 First, the transfer process is usually not complete as some residual particles are le in the aqueous phase. Second, in many cases, the transferred nanoparticles are not fully dispersed in nonaqueous solvents but rather agglomerate into larger clusters, which requires additional size-selection processes to remove the aggregates.…”