Is nanotechnology revolutionizing the paint and lacquer industry? A critical opinion.

Many paints for indoor and outdoor applications contain biocides and additives for protection against microbial, physical and chemical deterioration. The biocides should remain active as long as they are incorporated in the paint. Protection against microbial colonization should last at least a decade. Once the biocides are released they should degrade within a short time so that no accumulation in the environment can occur. The paint industry is not only focusing their research in producing better paint formulations with degradable biocides: they also consider using nanomaterials, such as nanosilver, nanocopper, nanozinc oxide, photocatalytic-active nanotitanium dioxide and nanosilica dioxide as additives for the protection of paints, against microbial degradation and physical and chemical deterioration. In the future nanomaterials should replace biodegradable biocides and improve the paint properties as well as impede colonization by microorganisms. At the time there is no guarantee that the nanomaterials in paints and façades will fulfill their task in the long run, since there are no long term studies available. From nanosilver doped paints it is known that silver is easily washed out by rain. Photocatalytic active nanotitanium dioxide adsorbs ultra violet light (UV-light) and generates hydroxyl radicals, which not only inhibit microbial growth but can also initiate or accelerate the photocatalytic degradation of the paint matrix. Thus at this time it is still unknown if it makes sense to incorporate nanomaterials into paints. Intensive research and development are still needed in order to find the answers.