Poly(dopamine) coated graphene oxide as multi-functional filler in waterborne polyurethane

Graphene oxide, known as an excellent reinforcing agent in polymer composites, was modified with dopamine and then incorporated into waterborne polyurethane (W-PU) via water solution blending. The addition of dopamine modified graphene oxide (D-GO) in W-PU is able to strengthen the stress transfer from the polymer matrix to the filler, and hence dramatically enhance the mechanical properties of the W-PU with increased ultimate Young's modulus and moderately improved elongation at break. Also, since poly(dopamine) contains abundant phenolic groups in the structure, this project also aims to improve the antioxidant property of polyurethane. Impressively, it is found that the D-GO filler significantly slows down the rate of photo-degradation and thermo-oxidative degradation, lowering the drops of tensile stress, yield strain and elongation at break after UV irradiation. Besides, compared with neat PU and 1 wt% D-GO containing W-PU nano-composite, in which even no electrical conductivity can be observed, nano-composites containing 4 wt% D-GO exhibits a considerable electrical conductivity up to 0.82 S m⁻¹. This work demonstrates that D-GO is not only a promising candidate in aiding PU as an impressive coating materials with excellent UV and thermal oxidation resistance, but also can act as an anti-static material. (paper)