GO-modified double-walled polyurea microcapsules/epoxy composites for marine anticorrosive self-healing coating

Abstract

In order to achieve microcapsules' higher encapsulating capacity and better self-healing efficiency, the graphene oxide (GO)-modified double-walled Polyurea microcapsules were synthesized with 1, 6-Diaminohexane as the inner core and isophorone diisocyanate (IPDI)-based prepolymer as the outer core. Measured were the morphology, structure, thermal property and mechanical property of the microcapsules by using the Optical and Scanning Electron Microscopy (OM, SEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and Nanoindentation tests. And the mechanical testing machine, Digital Speckle Correlation Method (DSCM) and Electrochemical Impedance Spectroscopy (EIS) measurement were used to evaluate their mechanical and anticorrosive properties. The results showed that the GO-modified microcapsules obtained possessed a good spherical shape with a mean diameter of 0.5 μm. The microcapsules with excellent thermostability containing a urea bond, the GO had been successfully embedded into the wall materials and the contents of the inner core materials and outer core materials were 26.75 wt% and 10.88 wt% respectively. The average Young's modulus, hardness and load during the holding time of the microcapsules were 2.708GPa, 0.088GPa and 28.51mN respectively. The mechanical and anticorrosive self-healing efficiency of epoxy coating with 3.0 wt% of microcapsules could gain up to 80.43% and 62.50% respectively.