Stabilizing Vaterite Using Polydopamine as the Stabilizer

ABSTRACT

This study presents an effective approach for synthesizing high‐purity, wet‐stable vaterite via a refined CO ₂ bubbling method, employing polydopamine (PDA) as both a crystal modifier and stabilizer. The effects of PDA on the properties of the resulting CaCO ₃ and the wet‐stability of vaterite were systematically investigated. The results revealed that the presence of PDA significantly increased the purity of the synthesized vaterite, with even a trace amount yielding 100% vaterite content. Furthermore, PDA led to a notable reduction in particle size and a substantial increase in the BET surface area of vaterite—by 30.6 to 41.3 times. The wet stability of vaterite under humid conditions (relative humidity = 75%) was remarkably improved, maintaining 100% purity without any phase transformation for up to 28 days. The enhanced purity and stability are attributed to two primary mechanisms: the chelation of Ca ²⁺ ions and the surface coating effect provided by PDA, through which the overall Gibbs free energy of CaCO ₃ particles can be reduced.