Page 551 - Book Hosokawa Nanoparticle Technology Handbook

25 DEVELOPMENT OF NEW COSMETICS BASED ON NANOPARTICLES APPLICATIONS
Table 25.1
Light reflection and scattering effect [7] of particles.
Particle Ratio of particle Light reflection and scattering Efficiency of
diameter diameter (D) to light scattering
wavelength
( ) of light Region Scattering, concealing equation

Large D Geometrical 3 M Small
optics region A 2 D (25.1 )

⎡ A: opticalshutoff area
⎢
⎢ M:massof pigment
⎣ ⎢ : density of pigment

2
Medium D Mie scattering D 09 . m 2 (25.2 ) Big
region opt n m 1
2
B

D opt (25.3)
2.1( n n )
p
B
m 2
2
D opt (25.4 )
2
.
1 414 n m 1
B
2
D opt (25.5 )
( n n )
p
B
⎡ D :particle diameter at maximum light
⎢ opt scattering
⎢
⎢ n p
⎢ m m = n
⎢ B
⎢ n :refelctive index of pigment
p
⎢
⎢ n : refelctive index oof colour spreading
B
⎢ ⎣ plastic
2
26
Small D Rayleigh scattering S ⎛ ⎜ m 1⎞ ⎟ 2 4 (25.6 ) Small
region ⎝ m 1⎠ 3
2
⎡
⎢
⎢ S: optical scattering coefficient
⎢ D/
⎢
⎢ m n p
⎢ ⎣ n B
Because of this nanocoating, the catalytic activity compounds in a hydrosilylation chemical reaction
of the nanoparticles is inactivated thereby preventing [11]. Fig. 25.4 shows a schematic diagram of func-
the deterioration of the fragrance, oils and agents tional nanocoating.
present together with the nanoparticles in cosmetics. Using this method, it is possible to give the desired
Si–H groups are present in this networked silicone, surface property to the core particles. For example, it
and it is possible here to introduce unsaturated is possible to control the dispersion by introducing

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