Highly transparent and scratch resistant polysiloxane coatings containing silica nanoparticles

Scratch properties of polysiloxane coatings are critical to their application in the many fields which require long-term protection and aesthetics. In this work, modified silica nanoparticles (m-SiO₂) containing epoxy group dispersed homogeneously in polysiloxane coatings by in situ polymerization process. The homogeneous dispersion of m-SiO₂ is beneficial to the scratch resistance, which has only slight effect on the transparency of polysiloxane coatings. According to the results of macro and nano scratch tests, the first critical loads for polysiloxane coating with 0.75 wt% m-SiO₂ were improved 66.7% and 73.3% respectively compared to pure polysiloxane coating. More impressively, the achieved coating also showed an outstanding transmittance of 91%, a high pencil hardness of 8H and a superior hardness of nanoindentation test (HIT), which was about 58.3% higher than pure coating. Additionally, the thermostability and abrasion resistance of the nanocomposite coatings were enhanced with various loadings of m-SiO₂. This study provides a facile and environmentally friendly method to reinforce scratch resistance of highly transparent polysiloxane nanocomposite coating, which is potential in the application of automobiles and home appliances.