Page 20 - Handbook of Surface Improvement and Modification

2.2 Additives used 15

2.2.2 CORE-SHELL NANOSILICA DERIVATIVES
Silica core-copolymer shell hybrid compounds were synthesized by copolymerization of
styrene, acrylonitrile, and methylmethacrylate on the surface of γ-methacryloxypropylt-
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rimethoxysilane modified nano silica ball. The core-shell hybrid materials were adjusted
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to form single spherical phase with a diameter of 200 nm. The addition of the core-shell
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hybrid materials to clearcoat enhanced its anti-scratch performance. Figure 2.13 shows
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SEM images of the additive. The average size of the nanosilica ball was tunable in the
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range 10-50 nm by a sol-gel process. The spherical nanosilica ball (30 nm) became 38
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nm after the reaction with γ-methacryloxypropyltrimethoxysilane. The average size of
nanosilica ball having core-poly(styrene-AN-MMA) shell structured hybrid material
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increased to 200 nm. Figure 2.14 shows the effect of increasing concentration of additive
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on anti-scratch performance which increased by 16%.

Figure 2.14. Panoramic images of clearcoats
deformed by lateral forces and point of first fracture
(L , mN) vs. the content of core-shell compounds.
c
[Adapted, by permission, from Kim, HC; Choi, KH;
Park, SK, Asian J. Chem., 24, 9, 4185-7, 2012.]

Figure 2.13. SEM images of nano silica ball core-
poly(styrene-AN-MMA) shell hybrid compounds.
[Adapted, by permission, from Kim, HC; Choi, KH;
Park, SK, Asian J. Chem., 24, 9, 4185-7, 2012.]