Thermoreversible Diels-Alder Healable Polymeric Systems for Corrosion Prevention

Self-healing of thermosetting materials is desirable to repair damage that can occur through aging, wear resistance, and internal fractures. The focus of this work was to be able to apply a self-healing microcapsule system to a coating in order to improve the coating's durability to provide better corrosion protection to the underlying metal substrate. Furthermore, the design of encapsulation methods was studied to also encapsulate corrosion inhibitors. Embedding corrosion inhibitors into a coating would allow for more targeted delivery of the inhibitor to an area of damage and impede the corrosion of the underlying metal. A furan functionalized epoxy-amine thermoset with an embedded microcapsule healing system that utilizes reversible Diels-Alder healing chemistry was developed. A urea-formaldehyde (UF) encapsulation technique was used to create capsules with average diameters of 150 and 58 μm, filled with reactive solutions of phenyl acetate (PA) and multimaleimides. These capsules were incorporated into a polymer matrix and coating and upon fracture, break to release maleimide into the crack interface where it can react with pendant furan groups. These studies showed that the use of PA as a solvent and the concentration and structure of maleimide healing agent affects the degree of physical and chemical bonding across the crack surface. In addition, a method to encapsulate a zinc based corrosion inhibitor was developed. These capsules along with capsules containing reactive healing solution were then incorporated into a furan-functionalized epoxy coating and evaluated for corrosion prevention. It was found that healing of the coatings and direct delivery of inhibiting solution to an area of damage have an effect on corrosion resistance within short time scales.Ph.D., Chemical Engineering -- Drexel University, 201