Value addition to waterborne polyurethane resin by silicone modification for developing high performance coating on aluminum alloy

Silicone–polyurethane waterborne coatings were synthesized using sol–gel technique for protecting aluminum and its alloys. These are derived using polyurethane (PU), hexamethoxymethylmelamine (HMMM) and silicones such as methyltrimethoxysilane (MTMS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) as precursors. Structural and morphological features of coatings were assessed using Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), atomic force microscopy (AFM) and scanning electron microscopy (SEM). Performance of the coatings was evaluated using potentiodynamic polarization studies, contact angle measurement, DSC/TGA, UV–vis spectrophotometer, and mechanical tests such as flexibility, pencil hardness test and impact resistance.