Nanoparticles bearing a photoreactive shell: Interaction with polymers and polymer surfaces

Photosensitive nanoparticles bearing azidophenyl units at their surface were prepared from amino functionalized silica nanoparticles with 4-azidophenyl isothiocyanate. Under UV irradiation, nitrene groups are formed and the nanoparticles react with their environment (e.g., matrix polymers). Azidophenyl modified nanoparticles have been investigated as photo-crosslinking agents for Cdouble bond; length as m-dashC unsaturated polymers (polyisoprene and a derivative of polynorbornene). Here, photo-functional nanoparticles act as non-migrating photo-crosslinkers. In another approach, the UV induced immobilization of azidophenyl functionalized nanoparticles on inert polymer surfaces (e.g., polyethylene foils, polyester and polyamide fibres) has been demonstrated. Under appropriate conditions, dense nanoparticle layers are covalently attached to the polymer surfaces. The use of photoreactive nanoparticles opens new fields of application because they can be coupled to virtually any polymer surface, without the necessity to carry out a pre-treatment or coating of the targeted polymer substrate.