A comparative study on long term stability of self-healing epoxy coating with different inorganic nanotubes as healing agent reservoirs

Self-healing epoxy coatings were prepared with different nanotubes as reservoirs for epoxy monomer (healing agent). The nanotubes selected for the current study were TiO2 nanotubes with two different tube diameter (TNT1 and TNT2) and naturally occurring hallyosite nanotubes (HNT). These self-healing coatings were subjected to accelerated weathering exposure. The weathering stability of the coatings were observed. The surface morphology, chemical changes and surface roughness were studied as a function of weathering exposure period. These studies confirmed that the long term stability of the coatings highly depend on the nanotube parameters such as nature, surface area and diameter. It was found that the photocatalytic degradation of epoxy matrix with TiO2 nanotubes was prominent in TNT1 filled coating compared with their TNT2 variant. The higher possibility of exposure of epoxy monomer encapsulated inside both HNT and TNT2 facilitated the cure reaction with UV light to create new chains during weathering.