Modification of gold and silver nanoparticles with n-dialkyldithiophosphates

• AgNPs and AuNPs synthesized via chemical reduction method.
• Effective method for AgNPs and AuNPs modification with n-dialkyldithiophosphates (DTP) developed.
• Stable colloids of AgNPs and AuNPs in hexane obtained.

The present paper describes a method for modification of gold (AuNPs) and silver (AgNPs) nanoparticles with n-dialkyldithiophosphates (DTP) via the phase transfer process. Two thiophosphoric acids with different chain lengths: di-n-dodecanethiophosphate (C12DTP) and di-n-heksadecanethiophosphate (C16DTP) were used as transfer agents of nanoparticles (NPs) from water to hexane. NPs synthesized by chemical reduction method in water were precisely characterized before the transfer process using atomic force microscopy (AFM) and transmission electron microscopy (TEM). The effectiveness of phase transfer process was studied by the UV–vis spectroscopy. Nanoparticle size and size distribution before and after the process were investigated using dynamic light scattering (DLS).Phase transfer process turned out to be an effective method to obtain stable AuNPs and AgNPs modified with di-n-dodecanethiophosphate and di-n-heksadecanethiophosphate in hexane. No changes in the absorption spectra position or in NPs size and size distribution were observed after the transfer process, showing that the n-dialkyldithiophosphate-modified AuNPs and AgNPs dispersed in hexane were colloidally stable. This indicates that long hydrocarbon chains of n-dialkyldithiophosphates provide nanoparticles sufficient hydrophobicity and dispersibility in hexane.

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