Ionic Liquid and Binary Solvent Assisted Preparation of Silk Fibroin and Polyethylene Glycol Film: Structural and Mechanical Properties

Silk fibroin (SF), a biodegradable and biocompatible material with excellent mechanical properties, is widely utilized in food packaging and medical applications. However, regenerated SF is inherently brittle, necessitating the addition of polyethylene glycol (PEG), a nontoxic and biocompatible plasticizer, to enhance its flexibility. In this study, SF-PEG films were fabricated using two solvent systems: a single solvent (1-butyl-3-methylimidazolium chloride, BMIM Cl) and a binary solvent system (BMIM Cl and dimethyl sulfoxide, DMSO). SL-PEG films were prepared using the single solvent, while SM-PEG films were produced with the binary solvent system. The structural, mechanical, and morphological properties of the films were compared. Results showed that the SM-PEG films exhibited excellent mechanical performance, with a tensile strength of 6.9 ± 0.7 MPa, a Young's modulus of 367.0 ± 42.9 MPa, and an elongation at break of 42.6% ± 4.0%, significantly outperforming the SL-PEG films. The enhanced performance of SM-PEG films was attributed to the improved dispersion of PEG within the SF matrix, facilitated by the binary solvent system. In conclusion, the binary solvent system effectively improved the flexibility and ductility of SF-PEG films, making them better suited for applications requiring robust and adaptable biomaterials, such as in food packaging and medical applications.