Crystallization Behavior and Molecular Dynamics Simulation of Poly(Lactic Acid) Film Toughened by Poly(Ethylene Glycol)‐Modified Carbon Dots

ABSTRACT In order to improve the crystallization properties and toughness of PLA film, poly(ethylene glycol) (PEG)‐modified carbon dots (CDs) were synthesized as nanofillers to achieve this goal. PEG‐CDs were characterized by Fourier transform infrared spectrometer (FTIR), static contact angle measurement, X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and thermogravimetric analyzer (TGA), and the results demonstrated that the PEG chains were successfully grafted onto the surface of CDs. PEG‐CDs/PLA composite films were prepared by extrusion blow molding technology, and their mechanical properties, thermal stability, anti‐aging performance, and water vapor barrier properties were investigated. The results showed that the elongation at break of PEG‐CDs/PLA composite films (0.05 wt%) increased from 19.43% (for pure PLA film) to 107.75%, and the water vapor barrier properties, thermal stability, and anti‐aging properties of PEG‐CDs/PLA composite films were improved to varying degrees compared with those of pure PLA film. The rheological behavior analysis of the PEG‐CDs/PLA composite film revealed that PEG‐CDs had a plasticizing effect on PLA, which is one possible cause for the increased toughness of the PEG‐CDs/PLA composite films over pure PLA film. Moreover, the results of the crystallization behavior proved that PEG‐CDs could not only improve the crystallinity of PLA but also accelerate its crystallization rate. Molecular dynamics simulations confirmed the presence of strong interactions between PEG‐CDs and PLA, thereby enhancing the overall performance of PLA films.