Page 283 - Book Hosokawa Nanoparticle Technology Handbook
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FUNDAMENTALS CH. 4 CONTROL OF NANOSTRUCTURE OF MATERIALS
Figure 4.6.12
The fine particle-wiring array prepared by drying patterning (a f): The same sample showing different rainbow structural
colors depending upon the direction of observation. (A~E): Microstructure of the fine particle-wiring array.
other than fcc (hcp) by the particle self-assembling method having the advantages of both processes has
phenomena from the colloid solution, which indi- been developed in order to realize the preparation of
cates the great potential of the self-assembling particle self-assembled agglomerate pattering [20]
process. and the preparation and patterning of spherical parti-
cle agglomerates [21].
(a) Two-solution self-assembly method
(b) Preparation of particle self-assembled collectives
Liquid-phase patterning and drying patterning have
advantages and disadvantages. In the liquid phase, pattering by two-solution method
there is the advantage of utilization of the electrostatic After making a self-assembled monolayer with the
interaction and reactions between the particles and the patterning of hydrophobic and hydrophilic regions
board against the disadvantage of less driving force on the silicon board, methanol solution with dis-
for the closest packing of particles. persed particles is dropped on it (Fig. 4.6.13). Then
In the process of the drying solution, the meniscus the solution is repelled from the hydrophobic region
force generated at the contraction of the colloid solu- and patterned along with the hydrophilic region.
tion and drying of solvent between the particles can After that, it is soaked in decalin solution, which is
be used as the driving force for the closest packing of barely soluble to methanol. With gradual solution of
particles, while there is the disadvantage that chemi- methanol in decalin, the area of methanol including
cal reactions are hardly made use of because of the the particles shrinks and the particles become closer
dynamic process. For these reasons, the two-solution to each other.
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