A combined mechanical, microscopic and local electrochemical evaluation of self-healing properties of shape-memory polyurethane coatings (available online)

In the present paper, a shape-memory polyurethane (SMPU) film consisting of a twosegmented
block co-polymer is presented as a novel organic coating for the protection of metals
against corrosion. When the coating is damaged, a physical self-healing and consequent recovery of the
barrier properties are induced after an increase of the temperature. Indeed, thermal treatment leads to
the relaxation of the soft matrix in the polymer and subsequent coverage of the damaged area. The
scanning vibrating electrode technique (SVET) is employed to visualize local variations of the
electrochemical activity in the damaged area of the SMPU coating, proving that the physical-repairing
of the film during the thermal treatment leads to a recovery of the protective properties of the coated
system. By using laser scanning confocal microscopy (LSCM), observation of the coating defect before
and after the thermal healing allowed to establish the efficiency of the polymer to cover the coating
defect qualitatively. Complementary experiments using dynamic mechanical analysis (DMA) allowed to
study the mechanical properties of the co-polymer under a gradient of temperature and to prove its
stability during the healing treatment.