TY - JOUR
T1 - Stratification of Colloidal Particles on a Surface
T2 - Study by a Colloidal Probe Atomic Force Microscopy Combined with a Transform Theory
AU - Amano, Ken Ichi
AU - Ishihara, Taira
AU - Hashimoto, Kota
AU - Ishida, Naoyuki
AU - Fukami, Kazuhiro
AU - Nishi, Naoya
AU - Sakka, Tetsuo
N1 - Funding Information:
We thank Ryosuke Sawazumi for assisting the force curve fitting. We thank Satoshi Furukawa for supporting preparation of Figure S4. We appreciate advice and comments from Atsushi Ikeda and Hiroshi Onishi. This work was supported by Grant-in-Aid for Young Scientists (B) from Japan Society for the Promotion of Science (15K21100) and partly supported by Grant-in-Aid for Scientific Research (B) from Japan Society for the Promotion of Science (15H03877) and JSPS Bilateral Open Partnership Joint Research Projects.
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/4/26
Y1 - 2018/4/26
N2 - Colloidal probe atomic force microscopy (CP-AFM) can be used for measuring force curves between the colloidal probe and the substrate in a colloidal suspension. In the experiment, an oscillatory force curve reflecting the layer structure of the colloidal particles on the substrate is usually obtained. However, the force curve is not equivalent to the interfacial structure of the colloidal particles. In this paper, the force curve is transformed into the number density distribution of the colloidal particles as a function of the distance from the substrate surface using our newly developed transform theory. It is found by the transform theory that the interfacial stratification is enhanced by an increase in an absolute value of the surface potential of the colloidal particle, despite a simultaneous increase in a repulsive electrostatic interaction between the substrate and the colloidal particle. To elucidate the mechanism of the stratification, an integral equation theory is employed. It is found that crowding of the colloidal particles in the bulk due to the increase in the absolute value of the surface potential of the colloidal particle leads to pushing out some colloidal particles to the wall. The combined method of CP-AFM and the transform theory (the experimental-theoretical study of the interfacial stratification) is related to colloidal crystallization, glass transition, and aggregation on a surface. Thus, the combined method is important for developments of colloidal nanotechnologies.
AB - Colloidal probe atomic force microscopy (CP-AFM) can be used for measuring force curves between the colloidal probe and the substrate in a colloidal suspension. In the experiment, an oscillatory force curve reflecting the layer structure of the colloidal particles on the substrate is usually obtained. However, the force curve is not equivalent to the interfacial structure of the colloidal particles. In this paper, the force curve is transformed into the number density distribution of the colloidal particles as a function of the distance from the substrate surface using our newly developed transform theory. It is found by the transform theory that the interfacial stratification is enhanced by an increase in an absolute value of the surface potential of the colloidal particle, despite a simultaneous increase in a repulsive electrostatic interaction between the substrate and the colloidal particle. To elucidate the mechanism of the stratification, an integral equation theory is employed. It is found that crowding of the colloidal particles in the bulk due to the increase in the absolute value of the surface potential of the colloidal particle leads to pushing out some colloidal particles to the wall. The combined method of CP-AFM and the transform theory (the experimental-theoretical study of the interfacial stratification) is related to colloidal crystallization, glass transition, and aggregation on a surface. Thus, the combined method is important for developments of colloidal nanotechnologies.
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U2 - 10.1021/acs.jpcb.8b01082
DO - 10.1021/acs.jpcb.8b01082
M3 - Article
C2 - 29611708
AN - SCOPUS:85046006958
VL - 122
SP - 4592
EP - 4599
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
SN - 1520-6106
IS - 16
ER -