Synthesis and Anticorrosion Properties of Self-Healing Polydimethylsiloxane Polyurea Coatings

Using polydimethylsiloxane (PDMS) in varying ratios with 4,4′-biphenyldicarboxaldehyde (BD) and isophorone diisocyanate (IPDI), a series of reversible dynamic bond cross-linked polymers with outstanding self-healing and corrosion resistance properties has been developed. The dynamic reversible imine bonds and hydrogen bonds enable rapid self-repair; meanwhile, the phenyl rings involving π-π stackings further enhance the healing capability. The polymer PDMS1.0-IPDI0.7-BD0.3 exhibits an excellent self-healing ability at RT, repairing fractures completely within 6 h. The coating has high hydrophobicity (contact angle: 118°), tensile strength (2.2 MPa), and stretchability (1,095%). Additionally, the Rct value (2.065 × 106 Ω·cm2) of PDMS1.0-IPDI0.7-BD0.3 coating is three orders of magnitude higher than that of Q235 substrate (0.923 × 103 Ω·cm2). Salt spray tests confirmed that the coating could effectively prevent corrosive ions from contacting the underlying Q235 substrate, significantly reducing the corrosion rate and enhancing the material’s overall durability.