Hybrid polysiloxane/polyacrylate/nano-SiO2 emulsion for waterborne polyurethane coatings

摘要

A hybrid polysiloxane/polyacrylate/nano-SiO2 emulsion, as a component in the formula of waterborne polyurethane coatings, was synthesized by multi-step modification. The hybrid emulsion was characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), particles size distribution analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The water absorption and hardness of films were investigated. The results showed that the initial decomposition temperature of polysiloxane polyacrylate emulsion (PSPAE) film was increased by 9% (from 335 degrees C of PAE to 365 degrees C of PSPAE) and the water absorption of the film was 1.7%. With the addition of polysiloxane pre-polymer, the contact angle of PSPAE films increases from 76.3 degrees to 96.7 degrees, suggesting that the PSPAE has excellent hydrophobicity. TEM images illustrated the PSPAE particle was well-dispersed and had a clear core-shell structure. Due to the addition of modified SiO2 nanoparticles, the hybrid emulsion film had better mechanical properties and waterproof. The test results showed that the hardness of hybrid emulsion film was 4 H when 2% modified SiO2 nanoparticles were added.