No abstract

Anticorrosive coatings are extensively investigated as a potential solution to prevent or at least retard metal corrosion occurrence. However, the actual breakthrough is still hampered by the risk of barrier properties loss because of the local failure of the coating. Self-healing coatings can effectively repair microcracks, but outstanding self-healing behavior is always accompanied by poor self-cleaning ability. Herein, we report a series of poly­(dimethylsiloxane) (PDMS) modified with a terephthalic aldehyde (TA)-polyurea (PDMS-TA-PUa) copolymer with a double reversible dynamic bond crosslinking network structure. The PDMS-TA-PUa coating exhibits fast and re-recycled self-healing behavior that heals cracks within 40–50 min at room temperature. The fast self-healing property is attributed to the dynamic nature of the imine bonds and hydrogen bonds in polymer networks. The PDMS-TA-PUa coating also shows great self-cleaning and anticorrosive ability, due to high hydrophobic, low surface energy, and high corrosion potential. Our work gives an insight into the design and preparation of multifunctional coating material with excellent anticorrosion performance, fast self-healing, and self-cleaning properties.

No abstract

Thin discontinuous gold films evaporated onto 150–230-Å-thick C substrates were irradiated with perpendicularly impinging MeV N, O, F, Cl, and Br ions up to fluences of 5×1015 ions/cm2 and fluxes up to 8×1011 ions/cm2 sec. Surprisingly rapid degradation of the gold films was found; in some cases, up to 2000 gold atoms per impinging ion were removed, as measured by Rutherford scattering. The degradation was also investigated by transmission-electron microscopy. The angular distribution of the ejected gold atoms was indicated by a simple collector experiment and found incompatible with chunk emission. The degradation is concluded to be caused by the same ionization mechanism as that occurring when fission fragments form tracks in discontinuous metal films. During irradiation, the remaining part of the film is found to be stabilized against further degradation by ionization-induced cracking of hydrocarbons.