Comparison of the mechanical strength of a monolayer of silver nanoparticles both in the freestanding state and on a soft substrate
Permanent link to this recordhttp://hdl.handle.net/10754/678671
MetadataShow full item record
AbstractA 7-nm-thick monolayer comprising myristate-capped silver nanoparticles (AgNPs) was fabricated by first drop casting an AgNP solution on the surface of a 10-100 μl water drop placed on a solid substrate. With the natural evaporation of the water, a monolayer slowly descended onto the substrate, the latter containing an array of 2.5-μm-diameter and 200-nm-deep holes, and finally formed circular freestanding monolayers in the holes. Nanoindentation measurement based on atomic force microscopy was carried out on the circular freestanding monolayer at its center, and the extending and retracting force-indentation curves were recorded to analyze further the mechanical properties of the monolayer. The force-indentation curves were evidently nonlinear, and so a two-term continuum-mechanics theory was used to interpret the results. By fitting the force-indentation curves using a two-term equation, the prestress and Young’s modulus of the freestanding AgNP monolayer were obtained as approximately 0.05 N/m and several gigapascals, respectively, which are consistent with the results reported in the literature. For comparison, we also studied the mechanical responses of AgNP monolayers and bilayers on a soft polydimethylsiloxane (PDMS) substrate by using nanoindentation. Because the AgNP monolayer was stiffer than the PDMS substrate, it was possible to measure the mechanical response of the former despite it being only 7 nm thick. The mechanical strength of the freestanding AgNP monolayers was considered to be dominated by the attractive interactions between the interdigitated hydrocarbon chains of the myristate.
CitationWang, P., Ryuzaki, S., Gao, L., Shinohara, S., Saito, N., Okamoto, K., … Yamada, S. (2019). Comparison of the mechanical strength of a monolayer of silver nanoparticles both in the freestanding state and on a soft substrate. Journal of Applied Physics, 125(13), 134301. doi:10.1063/1.5063567
SponsorsThis work was supported by JSPS KAKENHI (Grant No. 17K05006). We thank Dr. Zhen Cao (KAUST) for helpful discussions about the MD simulations of the interaction between organic molecules and Professor Vincent Craig (Australian National University) for helpful discussions about how surface charges on the silicon tip and PDMS affect the force measurement.
JournalJOURNAL OF APPLIED PHYSICS