Protection of organic pigments against photocatalysis by encapsulation

A model organic pigment (β copper phthalocyanine) was encapsulated by silica using water glass as a precursor. It is shown that the thickness, porosity and uniformity of silica shells (coatings) around individual pigment particles depend significantly on pH and temperature of synthesis. It is further demonstrated that the obtained silica shells can serve as an efficient protection against the highly reactive products of photocatalysis. The degree of protection depends not only on the thickness of silica shells but also on their porosity.