We tried to prepare talc-based pearl pigment using natural talc, which is cheap and has a smooth touch, by coating of fine titanium dioxide particles on it. Since commercial talc is generally soft and hydrophobic, the formation of hybrid materials with it having interference characteristics has not been realized up to date. However, we successfully have prepared talc-based pearl pigment using raw talc stone, which has a comparatively strong layer structure, by controlling its particle condition with wet grinding and water sieving, although the interference color was weaker than that of the conventional mica-based pearl pigment. This talc-based pearl pigment showed soft color which was caused by the combination of diffusion and interference lights developed by the right gap of ledge-shaped stepwise structure of talc layer that formed by partial peeling during the grinding. This talc-based pearl pigment may not be applicable to the same fields for the commercial pearl pigment, but we expect it to be used for cosmetics as an extender because of its very smooth touch and soft interference texture.
Polystyrene particle assembly on glass substrates were prepared by lifting the substrates out of the particle dispersion at a constant speed. There were a lot of cracks in 1.5μm width in the colloid crystals, and the average domain size of the colloid crystals was a few micrometers. We investigated the effects of the pulling speed of the substrates, temperature, and particle concentration of the dispersion on the amounts of cracks, and found that the minimum amounts of the cracks were obtained at the disperse concentration of 2.6wt%, the pulling speed of 80nm/s and 60°C. Further, it was found that the addition of agar to the dispersion resulted in the decrease of the amounts of the cracks.