UV-curable waterborne polyurethane dispersions modified with a trimethoxysilane end-capping agent and edge-hydroxylated boron nitride

In this study, waterborne polyurethane (WPU) dispersions were prepared using a trimethoxysilane end-capping agent (DAA-GPTMS) derived from diallylamine (DAA), (3-glycidoxypropyl)methyldiethoxysilane (GPTMS) and modified with edge-hydroxylated boron nitride (hBN-OH) nanosheets. The WPU films containing DAA-GPTMS possessed remarkable hydrophobicity and favorable water repellency, attaining a contact angle of 101.2 degrees and a 52% decrease in water absorption relative to those of the pure WPU. When the contents of DAA-GPTMS and hBN-OH were 7.5 wt% and 0.2 wt%, respectively, the synergetic effect between the DAA-GPTMS and the hBN-OH nanosheets greatly enhanced the physical and mechanical properties of the nanocomposite films, i.e., the stress doubled and the Young's modulus increased by fivefold compared to those of pure WPU. Embedding 0.2 wt% of the hBN-OH nanosheets in the WPU coatings resulted in a lower corrosion current density (1.0 x 10(-10) A cm(-2)) and more positive corrosion potential (- 0.63 V). The results demonstrate that WPU/hBN-OH nanocomposite coatings possess great potential for corrosion protection.