g‐C₃N₄‐Decorated Montmorillonite as a Dual‐Functional Nucleator: Enhancing Crystallization and Imparting Antibacterial Activity in Polyester Composites

Layered montmorillonite is frequently employed in the fabrication of polymer nanocomposites, with the aim of enhancing the mechanical properties, flame retardancy, and thermal stability of these materials. Beyond its role in augmenting the physical and mechanical attributes of polymeric materials by serving as physical cross‐linking points through non‐covalent interactions between inorganic and organic components, montmorillonite can also be endowed with novel properties through functional modification. We synthesized a heterogeneous nucleating agent endowed with antibacterial capabilities by depositing graphitic carbon nitride (g‐C 3 N 4 ) onto the surface of layered montmorillonite at elevated temperatures, thereby conferring superior antibacterial properties to the composite. During the polyester molding process, the crystallization rate and degree of crystallinity of the polyester are enhanced through the heterogeneous nucleation effect, which in turn significantly ameliorates the material's oxygen and water vapor barrier properties. Concurrently, the photocatalytic activity of the g‐C 3 N 4 on the montmorillonite surface generates reactive oxygen species, which exhibit bactericidal effects. This modified montmorillonite nucleating agent, with its integrated antibacterial functionality, is poised to be utilized in the fabrication and processing of biomedical and food packaging materials. Furthermore, it offers novel insights into the development of functional packaging materials with advanced properties.