Polyhedral gold nanocrystals/polyelectrolyte composite film: One-pot synthesis via interfacial liquid plasma polymerization

Abstract In contrast with the conventional in situ and ex situ methods for the preparation of polymer-based nanocomposites in which the polymer matrix (for both methods) and metal nanoparticles (for the ex situ method only) are prepared separately prior to being combined to form the composite, polyhedral gold nanocrystal/polymer composite film was successfully synthesized through combining the in situ formation of gold nanocrystals (AuNCs) and simultaneous polymerization of the polyelectrolytes from ionic liquids and surfactants under atmospheric pressure plasma. The composite film contained a large number of well-shaped polyhedral AuNCs. The AuNCs are stereoscopically distributed in the polyelectrolyte matrix without agglomeration. The size of the AuNCs prepared in a 3 mm deep reactor decreased along the cross section of the composite film from top to bottom, while they were uniform in size when they were prepared in a 5 mm deep reactor. In the presence of the Au precursors, the polymer film thickness increases to 7.03 μm, which is two-fold thicker than that of the polymer film prepared without adding Au precursors. Through the density functional theory (DFT) calculations, the critical role of Triton X100 was clearly demonstrated in the formation of the well-shaped AuNCs. The composite film exhibited the reduction of ∼66% in Young's modulus and the reduction of ∼44% in hardness compared to the neat polymer film. Finally, an appropriate mechanism is proposed for the formation of the polyhedral AuNC/polyelectrolyte composite film.