Performance properties of graphene oxide/water-borne polyurethane nanocoatings

Graphene oxide (GO) is a good nanofiller candidate for waterborne coatings because of its outstanding physical and mechanical properties, good dispersibility in water, and low cost relative to graphene. Scientists report on the performance of a one-part, water-borne polyurethane (WPU) nanocoating formulated with four different GO loadings ([0.4% to 2.0%] by mass).

The results show that GO sheets were well dispersed in, and have good adhesion to, WPU. At the higher mass loadings ([1.2% or 2%] by mass), GO increased the modulus and yield strength of WPU by 300% and 200%, respectively, increased the thermal conductivity by 38%, reduced the burning heat release rate (flammability) by 43%, and reduced the oxygen permeability by up to sevenfold.

GO as a viable nanofiller for WPU coatings
The presence of GO, however, increased water vapor uptake at high humidity; the moisture content of 2% mass loading GO/WPU nanocoatings at 90% RH was almost twice that of the moisture content for unfilled WPU. Overall, with the exception of water uptake at very high humidity (> 70% RH), the observed improvements in physical and mechanical properties combined with the ease of processing suggest that GO is a viable nanofiller for WPU coatings.