Page 555 - Book Hosokawa Nanoparticle Technology Handbook

26 DISPERSION CONTROL OF Al O NANOPARTICLES IN ETHANOL APPLICATIONS
2 3
materials too have a big future in the skincare area. [7] M. Kiyono: Titanium Oxide, Gihodo Shuppan, Tokyo,
Further, while nanoclusters such as gold or silver p. 131 (1991).
exhibit vibrant red or yellow coloration, even such plas- [8] P. Stamatakis, B.R. Palmer, G.C. Salzman, C.F. Bohren
mon coloration will be used in make-ups in the future. and T.B. Allen: J. Coat. Technol., 62, 95 (1990).
[9] H. Fukui, R. Namba, M. Tanaka, M. Nakano and
S. Fukushima: J. Soc. Cosmet. Chem., 38, 385 (1987).
References
[10] H. Fukui, T. Ogawa, M. Nakano, M. Yamaguchi and
[1] H. Sagitani: J. Am. Chem. Soc., 58, 738 (1981). Y. Kanda: in Controlled Interphases in Composite
[2] K. Shinoda, H. Saito: J. Colloid Interface Sci., 26, 70 Materials, H. Ishida (Ed.), Elsevier Science Publishing
(1968). Co. Inc., New York, p. 469 (1990).
[3] H. Sagitani, Y. Hirai, K. Nabeta and M. Nagai: J. Jpn. [11] F.C. Whitemore, P.W. Pietrusza and L.H. Sommer:
Oil Chem. Soc., 35, 102 (1986). J. Am. Chem. Soc., 69, 2108 (1947).
[4] Y. Kumano, S. Nakamura, S. Tahara and S. Ohta: [12] Japan Patent Number 1635593.
J. Soc. Cosmet. Chem., 28, 285 (1977). [13] K. Ohno: Fragrance J., 22, 11 (1994).
[5] H. Nakajima, T. Tomomasa and M. Kouchi: J. Soc. [14] K. Ohno: J. Soc. Cosmet. Chem. Jpn., 27, 314 (1993).
Cosmet. Chem. Jpn., 23, 288 (1990). [15] K. Ogawa: Proceedings of 43rd SCCJ conference (1998).
[6] M. Fujii, T. Kawai and N. Kawai: Oyo Buturi, 53, 916 [16] E. Kawai, Y. Kohno, K. Ogawa, K. Sakuma,
(1984). N. Yoshikawa and D. Aso: IFSCC Mag., 5, 269 (2002).

APPLICATION 26

26 DISPERSION CONTROL OF Al O NANOPARTICLES IN ETHANOL
3
2

It is quite difficult to handle a nanoparticle powder, the dispersibility of nanoparticles in dense
because of aggregation due to the high surface inter- suspensions.
action between nanoparticles, which have a large spe-
cific surface area and high surface energy. Therefore, In this chapter, the action mechanism and selection
by using a dense suspension, the nanoparticle powder of the polymer dispersant on Al O nanoparticles
3
2
makes easier to disperse up to primary particles and to ethanol suspension is clarified, based on the surface
handle and facilitate transport, and then that can pro- interaction using nanocolloidal probe AFM [2, 3].
duce its original performance. To obtain a homoge-
neous suspension with a high concentration and
adequate fluidity, the aggregation and dispersion 1. Effect of molecular weight of PEI on nanoparticle
behavior of particles is usually controlled by using a suspension viscosity
polymer dispersant. However, there are some prob-
lems to produce a nanoparticle suspension using a When using 7, 30, 100 and 370 nm scaled Al O 3
2
polymer dispersant [1]. For example: nanoparticles, the aggregation and dispersion
behavior of the Al O nanoparticles in dense ethanol
3
2
1. It is difficult to disperse a nanoparticle in a suspensions was investigated. Six kinds of branched
dense suspension with a high concentration, polyethyleneimines (PEIs) (Epomin, Nippon
because the distance between particles will be Syokubai Co., Ltd., Japan) with a molecular weight
(MW) ranging from 300 to 70,000 were used in this
less than several nanometers and the particles
study as polymer dispersants which is effective in
will readily aggregate at the distance.
the dispersion of ceramic particles in ethanol [4, 5].
2. As for a nanoparticle, the steric repulsion pro- Fig. 26.1 shows the representative molecular struc-
motes a dominant dispersibility and stability in ture of the branched PEI.
suspensions, because the surface potential To clarify the relationship between the suspension
viscosity of each nanoparticle and the MW of
between nanoparticles is at least over 100 mV in
branched PEIs, the apparent viscosity at the same
order to disperse nanoparticles.
shear rate (300 1/s) of suspensions as a function of
3. The molecular size of a polymer dispersant the MW of branched PEIs is plotted in Fig. 26.2. The
with approximately several nanometers affects suspension with the Al O nanoparticles of 100 and
2 3
527