Self-healing mineralization and enhanced anti-corrosive performance of polyurethane CaCO3 composite film via β-CD induction

A novel organic composite coating was successfully fabricated through in situ mineralizing in artificial seawater for a lasting anti-corrosive coating. The mineralized composite films make full use of the advantages including rich hydroxyl group and special ring structure of β-cyclodextrin as well as superior adhesion and high flexibility of waterborne polyurethane coating. The results show the β-CD remarkably promotes the mineralization of CaCO 3 on WPU substances through the effective adsorption and complexation of hydrophobic cavity to calcium ions. The dense organic-inorganic composite film exhibits outstanding anti-corrosive performance with corrosion rate of 1.39 × 10 −3  mm/year for 3CD-WPU sample, being much less than 7.36 × 10 −2  mm/year for WPU coating under same conditions. The excellent anti-corrosion performance is mainly attributed to the uniform nucleation site provided by CD-WPU and further formation of dense CaCO 3 film. Furthermore, the radial distribution function and adsorb energy theoretic analysis by molecular dynamic simulation definitely reveal and support the mechanism of β-CD promoting the CaCO 3 mineralization.