For many applications, thermoplastics possess many desirable properties such as low weight, high impact strength and good processability. However, a major drawback of thermoplastics over metals, ceramics, or thermosets is low scratch and mar resistance. As a result, many thermoplastic applications require a hard coating to impart abrasion resistance to the article. As a means to increase the hardness and abrasion resistance of coatings for plastic substrates, the addition of organically modified silica particles to organic coatings has been investigated.1
The first organically modified silicates were independently prepared by Philipp and Schmidt2 in 1984 and Wilkes, Orler, and Huang in 1985.3 These new inorganic-organic hybrids were named ORMOSILs by Schmidt and Ceramers by Wilkes. The term ORMOSIL has since been used extensively to describe organically modified silicate nanoparticles.A variety of organic groups have been grafted onto the surface of silica particles using organosilanes. For example, Chu et al.6 prepared epoxy functional silica particles by condensing glycidoxypropyltrimethoxysilane on to the surface of colloidal silica particles.