Enhanced Solar Reflectance and Superhydrophobic Properties of Functionalized Silica-Coated Copper Phthalocyanine Pigments by the Sol-Gel Process.

This research studies the physical, superhydrophobic, and optical properties of functionalized silica-coated copper phthalocyanine (CuPc) pigments. The silica coating was confirmed by the size increase and the atomic ratio of silicon and copper of the coated pigments. Under optimal conditions, the green and blue shades of the pigments were enhanced as indicated by the increase in solar reflectance at 450-540 nm for the CuPc green and 380-520 nm for the CuPc blue. The total near-infrared (NIR) reflectance of the CuPc green and blue also increases by 10.6 and 11.5% compared to the uncoated pigments, respectively. The functionalized silica layer also adds a superhydrophobic property to the pigments. The contact angles of the functionalized pigments with water and oil are 154.4 and 54.3° for the CuPc green pigment and 142.9 and 78.1° for the CuPc blue pigment, respectively. The improved optical and hydrophobic properties make the pigment suitable for outdoor applications as an advanced protection layer to slow down material degradations from heat and humidity.