Advanced Surface-Engineered Water-Based Paints for Antibacterial and Mechanical Resilience in Harsh Environments

Water-based paints commonly used on exterior surfaces, such as those in marine environments, swimming pools, transportation, railings, and construction, often exhibit poor mechanical strength and antimicrobial efficacy. This study presents an innovative approach to enhance these properties by incorporating hollow ceramic microcore (HCM) microadditives derived from fly ash waste. A core-shell fabrication technique is employed to produce HCM@TiO₂ microadditives, where the mullite (Al₆Si₂O₁₃) based HCM core is encapsulated with a shell of anatase-phase titania (TiO₂). Adding 4 wt% of these microadditives to the water-based paint significantly improve its properties, including a 90% reduction in bacterial growth and notable enhancements in creep resistance and hardness. Mechanical testing demonstrate a 9.14% increase in hardness (from 0.288 to 0.317 GPa) and a 22.67% increase in reduced modulus (from 6.589 to 8.516 GPa), along with improved creep resistance. Surface characterization show that the areal roughness (Sa) increased from 0.198 to 0.275 μm, promoting stronger interlocking, while gloss values decrease moderately from 71.1 to 60.0 GU, indicating a trade-off between durability and optical finish. These findings highlight the dual functionality of HCM@TiO₂ as a sustainable additive that simultaneously improves antibacterial efficacy and mechanical resilience, demonstrating a promising pathway for waste valorization and next-generation eco-friendly coatings.