Preparation and characterization of crystalline poly(L‐lactic acid)/silica nanocomposite films with high ductility and gas barrier properties

Abstract Incorporating inorganic particles is a common approach to preparing polymeric materials with desirable physical properties and processability. However, this often results in increased brittleness, necessitating methods to improve melt strength and toughness. In this study, in situ polymerization was employed to functionalize silica nanoparticles with the silane coupling agent (3‐aminopropyl) triethoxysilane (APTES) as a core. A flexible chain segment, poly(butylene itaconate) (PBI), was then introduced as a “rubbery” intermediate layer, resulting in a core‐shell structure of poly(L‐lactic‐co‐butanediol itaconate) nano‐silica copolymer films (PLBISiO ₂ ) with both branched and “rubbery” structures. Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) confirmed the formation of macromolecular chains, with the molecular weight ( M _n ) of PLBI increasing from 59,638 to 74,306 g/mol. This significant increase supports the “rubbery” core‐shell structure. When 0.5% SiO ₂ was added, the T _5% of the film increased by 40°C, significantly improving thermal stability. Additionally, the elongation at break increased to 265.7%, while retaining the original tensile strength. Dynamic rheology experiments further confirmed the generation of branched or “rubbery” core‐shell structures, and a doubling of gas barrier properties was observed with increased silica nanoparticles, suggesting potential applications in food packaging or biopharmaceuticals. Highlights Nanocomposites with core‐shell structure and improved mechanical properties. Dynamic rheology experiments confirmed the formation of the core‐shell structure. Significantly improved gas barrier properties due to core‐shell structure.