Size-Dependent Stiffness of Nanodroplets: A Quantitative Analysis of the Interaction between an AFM Probe and Nanodroplets.
The interfacial properties of nanodroplets are very significant for the exploration of the basic law governing the fluid behavior at the nanoscale and also the applications in some important processes in novel materials fabrication by forming a special and local reaction environment. However, many basic factors such as the interfacial tension or stiffness of nanodroplets are still lacking, partially because of the difficulty of making quantitative measurements of the interfacial interactions at the nanometer scale. Here, we used a novel atomic force microscopy (AFM) mode, PeakForce mode, to control the interaction between an AFM probe and nanodroplets, by which we could obtain the morphology and stiffness of nanodroplets simultaneously. The change in the stiffness with the size of the nanodroplets was observed where the smaller nanodroplets usually had a larger stiffness. To explain this phenomenon, we then established a theoretical model based on the Young-Laplace equation in which the deformation and size-dependent stiffness could be described quantitatively and the experimental observations could be explained with our numerical calculations very well. The general methodology presented here could also be extended to analyze the relevant behavior of nanobubbles and other wetting phenomena at the nanoscale.
University of Chinese Academy of Sciences , Beijing 100049, China.
Shuo
S
Wang
University of Chinese Academy of Sciences , Beijing 100049, China.|Shanghai Synchrotron Radiation Facility, Shanghai 201204, China.
Xingya
X
Wang
School of Mechanics and Engineering, Southwest Jiaotong University , Chengdu 610031, China.
Binyu
B
Zhao
University of Chinese Academy of Sciences , Beijing 100049, China.|Shanghai Synchrotron Radiation Facility, Shanghai 201204, China.
Lei
L
Wang
School of Physical Science and Technology, ShanghaiTech University , Shanghai 201204, China.
Jie
J
Qiu
University of Chinese Academy of Sciences , Beijing 100049, China.
Limin
L
Zhou
Life and Environment Science College, Shanghai Normal University , Shanghai 200234, China.
Yaming
Y
Dong
Bin
B
Li
Junhong
J
Lü
Ying
Y
Wang
Yi
Y
Zhang
Shanghai Synchrotron Radiation Facility, Shanghai 201204, China.
Lijuan
L
Zhang
University of Chinese Academy of Sciences , Beijing 100049, China.
Jun
J
Hu