Fundamental Methods for the Phase Transfer of Nanoparticles

Abstract

The utilization of nanoparticles for a variety of applications has raised much interest in recent years as new knowledge has emerged in nanochemistry. New and diverse methods for synthesis, characterization, and application of these particles have been discovered with differing degrees of ease and reproducibility. Post-synthetic modification of nanoparticles is often a required step to facilitate their use in applications. The reaction conditions and chemical environment for the nanoparticle synthesis may not support or may conflict with further reactions. For this reason, it is beneficial to have phase transfer methods for nanoparticles to allow for their dispersion in a variety of solvents. Phase transfer methods are often limited in the types and sizes of particles that can be effectively dispersed in an immiscible solvent. Currently, general transfer methods for a wide variety of nanoparticles have not been identified. New routes for phase transfer allow for utilization of a larger range of particles in applications which were previously limited by solubility and reactivity issues. In this work, we will describe the fundamental methods for the phase transfer of metallic nanoparticles. We will look at the major problems and pitfalls of these methods. The applications of phase transfer will also be reviewed, mainly focusing on catalysis and drug delivery.

Long-Chain Hydrosilanes Mediated Phase Transfer of Aqueous Metal Nanoparticles

“…Some methods yield good control over size and monodispersity, but little control over the shape of the nanoparticles [14][15][16]. Post-synthetic modification of the nanoparticles is often a required step to tailor the chemical, physical, and optical properties for specific applications [17,18].…”

“…It is desirable to develop methods and protocols which will open avenues for the transfer of metal nanoparticles between aqueous and organic media [17,19,20]. Novel metal nanoparticles have been commonly produced in aqueous solutions, as the synthesis involves a simple pathway [7].…”

“…Novel metal nanoparticles have been commonly produced in aqueous solutions, as the synthesis involves a simple pathway [7]. Generally, they are transferred to organic media for more practical use through a variety of methods [14][15][16][17][20][21][22][23][24]. The phase transfer of metal nanoparticles is commonly carried out by ligand exchange, utilizing alkyl amines and thiols with differing chain lengths [7,14,[16][17][18][19][20][21][22][23][24][25].…”

“…Generally, they are transferred to organic media for more practical use through a variety of methods [14][15][16][17][20][21][22][23][24]. The phase transfer of metal nanoparticles is commonly carried out by ligand exchange, utilizing alkyl amines and thiols with differing chain lengths [7,14,[16][17][18][19][20][21][22][23][24][25]. However, these methods are not compatible with certain types and sizes of nanoparticles; many require a prestabilization step [7,14,[16][17][18][19][20][21][22][23][24][25].…”

“…The phase transfer of metal nanoparticles is commonly carried out by ligand exchange, utilizing alkyl amines and thiols with differing chain lengths [7,14,[16][17][18][19][20][21][22][23][24][25]. However, these methods are not compatible with certain types and sizes of nanoparticles; many require a prestabilization step [7,14,[16][17][18][19][20][21][22][23][24][25]. Due to the variety of applications that require metallic nanoparticles in an organic solution, new transfer protocols to produce stable metallo-organic sols can be very useful and important.…”