Developments of organic-inorganic hybrid free radical-cationic dual cured coatings

Organic-inorganic nanocomposite hybrid coatings were prepared through a dual-cure process involving free-radical and cationic photopolymerization of a methacrylic-epoxy functionalized resin and subsequent condensation of organo-alkoxysilane inorganic precursor. All the formulations investigated gave rise to photocured films characterized by a high gel content values. A lower decrease on glass transition temperature is observed in the presence of MEMO or GPTS compared with a monofunctional methacrylic monomer. The dual-cured hybrid films were optically transparent evidencing that the organic-inorganic phase separation is in the scale of smaller than 400 nm. The formation of nanometric size inorganic domains (in the range between 10-30 nm), both in the presence of MEMO or GPTS as silica precursor, were further confirmed by TEM analysis.