Structure and mechanical properties of polyurethane/silica hybrid coatings

Polyurethane/silica hybrid coatings were prepared via in situ (IS) or blending (BL) method using different acidic silica sols. The effects of preparation methods, silica types, and content on the structure and mechanical properties of the hybrid coatings were investigated. It was found that there existed two types of silica phases in the hybrid coatings: silica-rich agglomerate and primary silica-rich phase, whose size and compactness depended upon the silica types and the preparation methods. Introducing silica could result in obvious changes in surface free energy, atomic composition, and mechanical properties of the hybrid coatings.