High performances polyurethane-urea polyacrylate hybrid emulsion coatings with multiple crosslinking structures

摘要

In this article, polyurethane-urea polyacrylate hybrid emulsions were synthesized via emulsion copolymerization of acrylate monomers, vinyltriethoxysilane (VTES) and anionic polyurethane-urea prepolymer with acrylate groups as the reactive emulsifier. Using waterborne polycarbodiimide as the crosslinker, room temperature multiple crosslinking hybrid coatings were fabricated successfully. Besides the crosslinking between polycarbodiimide and carboxyl groups, the polymerization crosslinking between polyurethane-urea and polyacrylate and the crosslinking of polyacrylate by VTES were confirmed by analyzing the crosslinking degree, FT-IR spectra and DSC curves. As more polycarbodiimide was used to consume hydrophilic carboxyl groups within the coatings, the water resistance increased considerably as well as the improvement in tensile strength. At poly-propylene glycol and polyether amine molar ratio of 1:2, strengthening and toughening phenomenon were observed in tensile test of the hybrid films. At which the hybrid coatings demonstrated high impact strength and flexibility. However, higher weight ratios of methyl methacrylate and butyl acrylate resulted in brittle coatings.