Phase Transfer Of Nanoparticles Research Articles

Exploring the Generality of PVP‐Assisted Phase Transfer of Nanoparticles

AbstractFor most nanoparticles, the synthetic environment usually differs from the application environment, making phase transfer a critical bottleneck in the exploration of nanotechnology. Herein, a general phase transfer method by using polyvinyl pyrrolidone (PVP) and an intermediate solvent is demonstrated. A variety of nanoparticles can be transferred into different media, such as water, polar organic solvent, nonpolar solvent, and polymer precursor, while maintaining their colloidal stability. In the traditional methods of two‐phase transfer, the initial solvent is a powerful competitor, which greatly limits the window of applicable conditions. A two‐step approach where the incubation with the intermediate solvent removes the initial solvent and allows sufficient time for ligand exchange is designed. This avoids the complications caused by partial ligand exchange at the limited area of the interface. Such a method of general phase transfer to different solvents and the understanding of the underlying mechanism would broaden the application of nanomaterials.

Fundamental Methods for the Phase Transfer of Nanoparticles.

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.

Introducing Students to Surface Modification and Phase Transfer of Nanoparticles with a Laboratory Experiment

A simple, reliable, and cost-effective experiment is presented in which students synthesized citrate-capped gold nanoparticles (GNPs), functionalized them with poly(ethylene glycol) (PEG), and transferred the PEG-GNPs from water to the organic phase dichloromethane. The experiment introduces students to nanotechnology with foci on important concepts including surface modification of nanoparticles, colloidal stability, and phase transfer. The proposed experiment was evaluated at three different universities to confirm its reproducibility and versatility. Collectively, the proposed experiment is suitable to be implemented into colloid- or nanoscience-related curricula.

Phase transfer of TiO2 nanoparticles from water to ionic liquid triggered by phosphonic acid grafting.

Controlling the interface between TiO2 nanocrystals and ionic liquids is of high fundamental and applied interest for energy storage and conversion devices. Phase transfer of nanoparticles from a synthesis medium to a processing or an application medium plays a significant role in nanotechnology. Here we demonstrate that surface modification with phosphonic acids bearing cationic end-groups can trigger the phase transfer of TiO2 nanoparticles from an aqueous sol to a typical water-immiscible ionic liquid, [Emim][NTf2]. The transfer involves both the grafting of the phosphonic acid moiety and the exchange of the counter ion of the cationic end-group by NTf2 anions, as demonstrated by solid-state NMR, elemental analysis and independent grafting and ion exchange experiments. Furthermore, the colloidal stability of the TiO2 sols in [Emim][NTf2] strongly depends on the hydrophobic character of the cationic end-groups.

Phase Transfer of Nanoparticles Using an Amphiphilic Ionic Liquid.

The phase transfer of nanoparticles (NPs) from water to organic solvents by an amphiphilic room-temperature ionic liquid (IL) was reported. The geminal IL modified with Pluronic P123 stabilizes a variety of NPs of different size and nature, such as Pd, Au, Ag, and SiO2 NPs. Their phase transfer into a hydrophobic environment was realized by raising the temperature and adding salts (such as NaCl and KBr), both of which have a common effect of breaking the hydrogen bonds of the IL with H2O. A more straightforward method of using an organic solvent working as a hydrogen bond donor (such as butyl alcohol) was then proposed. In this case, NaCl was no longer required. To further apply this strategy to the organic solvents that are generally incapable of forming hydrogen bonds (e.g., toluene), a small quantity of benzoic acid was added to the organic phase. By forming hydrogen bonds from benzoic acid to the IL, an even more facile approach was provided. FT-IR confirmed the hydrogen bonding between them. The phase-transfer protocol does not rely on coordination bonding of ligands with a specific metal and is capable of the phase transfer of objects with large sizes and different natures. Thus, it has the potential for wide application.

Simple phase transfer of nanoparticles from aqueous to organic media using polymer colloids as carriers

A simple and versatile method of the phase transfer of nanoparticles from aqueous to organic media using charged polymer colloids as carriers is proposed.

The influence of the chain length and the functional group steric accessibility of thiols on the phase transfer efficiency of gold nanoparticles from water to toluene

Abstract This paper describes the influence of the chain length and the functional group steric accessibility of thiols modifiers on the phase transfer process efficiency of water synthesized gold nanoparticles (AuNPs) to toluene. The following thiols were tested: 1-decanethiol, 1,1-dimethyldecanethiol, 1-dodecanethiol, 1-tetradecanethiol and 1-oktadecanethiol. Nanoparticles (NPs) synthesized in water were precisely characterized before the phase transfer process using Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). The optical properties of AuNPs before and after the phase transfer were studied by the UV-Vis spectroscopy. Additionally, the particle size and size distribution before and after the phase transfer of nanoparticles were investigated using Dynamic Light Scattering (DLS). It turned out that the modification of NPs surface was not effective in the case of 1,1-dimethyldecanethiol, probably because of the difficult steric accessibility of the thiol functional group to NPs surface. Consequently, the effective phase transfer of AuNPs from water to toluene did not occur. In toluene the most stable were nanoparticles modified with 1-decanethiol, 1-dodecanethiol and 1-tetradecanethiol.

Hydrogen‐Bond‐Selective Phase Transfer of Nanoparticles across Liquid/Gel Interfaces

In the swim: Colloidal nanoparticles coated with polylactide (PLA, red) and poly(ethylene glycol) brushes (PEG, black) can transfer from organic to aqueous phases across liquid/liquid or liquid/gel interfaces during degradation of the PLA coating (see picture: first step), which is driven selectively by the hydrogen bonding of the PEG coating with the aqueous phase (second step).

Hydrogen‐Bond‐Selective Phase Transfer of Nanoparticles across Liquid/Gel Interfaces

AbstractSchwimmunterricht: Kolloidale Nanopartikel mit Bürsten aus Polylactid (PLA, rot) und Poly(ethylenglycol) (PEG, schwarz) als Schale können über Flüssig‐flüssig‐ oder Flüssigkeits‐Gel‐Grenzflächen von einer organischen in eine wässrige Phase wechseln (siehe Bild: erster Schritt). Ursache ist die Zersetzung des PLA‐Überzugs und die Bildung von Wasserstoffbrücken zwischen den PEG‐Bürsten und der wässrigen Phase (zweiter Schritt).magnified image