Distinguishing Nanoparticle–Nanoparticle Interactions between Gold and Silver Nanoparticles Controlled by Gemini Surfactants: Stability of Nanocolloids
Shawn Riedesel, Rajpreet Kaur, Mandeep Singh Bakshi
Abstract
Nanoparticle–nanoparticle (NP–NP) interactions were studied by choosing oppositely charged colloidal suspensions of Au and Ag NPs. For this purpose, sodium dodecyl sulfate-stabilized Au NPs were titrated with a series of Gemini surfactant (i.e., 12-n-12 and 16-n-16)-stabilized Ag NPs to demonstrate the effect of head group and hydrophobic tail modifications on the Au–Ag NP interactions. The purpose of selecting Au and Ag NPs was to monitor and differentiate among their individual colloidal behaviors in the course of NP–NP interactions by simultaneously conducting UV–visible, size, and ζ potential measurements. All colloidal properties demonstrated a significant change in the event of Au–Ag NP complex formation during NP–NP interactions. Nanomaterial analysis indicated a high degree of inter-particle fusion among Au and Ag NPs with a high Au–Ag mole ratio for strongly interacting Au–Ag NPs systems but a low Au–Ag mole ratio for the systems where interactions were screened by modifying the molecular structure of Gemini surfactants. Results concluded that it is possible to screen or delay the NP–NP interactions even for strongly interacting systems simply by incorporating a non-polar spacer in the head group region or by increasing the length of hydrocarbon chains of the Gemini surfactant, thus producing colloidal suspensions with a longer shelf life and better industrial applicability.