Langmuir monolayer with growing nanocrystals

► Octadecylamine monolayer produces Au nanoparticles on aqueous HAuCl4 subphase. ► Au nanoparticles (NPs)/nanocrystals (NCs) are effectively disc-like. ► Worm-like NPs become globular and with time gets crystal structure. ► Two different growth zones have been identified for the accumulation of Au NPs.