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.