Surface‐Engineered TiO₂ Nanocomposite Latexes: Mini‐Emulsion Polymerization of High‐Solids Acrylic Coatings With Enhanced Thermo‐Mechanical and Antimicrobial Performance

Nanocomposite coatings are gaining attention for their multifunctional properties like enhanced mechanical strength, thermal stability, and antimicrobial efficacy. TiO 2 ‐based nanocomposites stand out due to their cost‐effectiveness, chemical stability, and non‐toxicity. However, creating a stable, high‐solids (> 50%) nanocomposite latex with evenly distributed nanoparticles throughout the dispersion is still a significant challenge. In this study, we report the synthesis of a high‐solids (~56 wt%) acrylic copolymer latex, poly(methyl methacrylate‐ co ‐butyl acrylate‐ co ‐acrylic acid) [P(MMA‐ co ‐BA‐ co ‐AA)], incorporating both pristine TiO 2 (pTiO 2 ) and acrylate‐functionalized TiO 2 (mTiO 2 ) nanoparticles via mini‐emulsion polymerization. Two distinct incorporation strategies were employed: (1) in‐ situ polymerization, where (both modified/unmodified) nanoparticles were introduced during monomer conversion, and (2) ex situ blending, where pre‐formed latex was mixed with nanoparticles. Particle size distribution and zeta potential measurements with time confirmed that in situ incorporation yielded less stable particle size and superior colloidal stability, attributed to covalent interactions between mTiO 2 and the growing polymer chains. Thermal (TGA, DSC) and mechanical (UTM) analyses showed that mTiO 2 nanocomposites had improved thermal degradation resistance (over 20°C increase in T 50 ) and tensile strength (over 30% improvement) compared to pTiO 2 and neat copolymer. Insitu mTiO 2 composites outperformed ex situ ones, indicating the importance of interfacial bonding. Importantly, the nanocomposite films exhibited significant antimicrobial activity against both Staphylococcus aureus and Escherichia coli , with mTiO 2 demonstrating ~50% greater inhibition than pTiO 2 . These results suggest that surface‐functionalized TiO 2 improves thermo‐mechanical performance and antifouling properties, making the high‐solids latex a good option for advanced coatings.