The effects of the π-π stacking interactions on the patterns of gold nanoparticles formed at the air-water interface

Benzyl-n-hexadecyl dimethylammonium chloride (BHDC) monolayer-stabilized gold nanoparticles were synthesized in a two-phase liquid-liquid system and found to self-assemble into varied structures under the control of temperature at the air-water interface. It has been demonstrated that the pi-pi stacking interactions between the capping agent molecules significantly affect the formation of the unique patterns. A possible mechanism based on Marangoni-Benard convection in the evaporating droplets and pi-pi stacking interactions was proposed. Four surfactants with similar structures: N-hexadecyl-N-methylpyrrolidinium bromide (C16MPB), 1-hexadecyl-3-methylimidazolium bromide (C(16)mimBr), 1-(2,4,6-trimethylphenyl)-3-hexadecylimidazolium bromide (C(16)pimBr) and hexadecyltrimethylammonium bromide (CTAB) were also used to further verify the formation mechanism mentioned above.