Tailoring the crystallization and melting behavior of 3D protein-polymer biocomposite materials: A study of pressure-induced silk fibroin/poly (L-lactic acid) foams

Crystallization and melting behavior of 3-D composite materials is critical in the field of biopolymer materials, because the crystal structure and crystallization kinetics of the materials will affect the performance of the biocomposite materials and their fabrication process. In this study, thermal analysis combined with structural analysis such as X-ray diffraction (XRD) were used to study the melting behavior of silk fibroin/polylactic acid (SF/PLA) composite foam materials prepared under a pressure of 0-6 MPa, and the mechanism of their isothermal crystallization kinetics was discussed. The results showed that both & alpha; and & alpha;'-type crystals exist in the composite material, and their contents can be tuned by isothermal crystallization temperature. When the isothermal crystallization temperature is around 105 degrees C, the crystallization time is the shortest and the crys-tallization rate is the fastest. Besides, silk fibroin can shorten the crystallization half-life of the composite foam and improve the crystallinity of the material. However, the high isothermal temperature will facilitate the interaction between SF and PLA segments to slow down the diffusion, folding and crystallization of the PLA segments. Using Avrami analysis, it is found that the crystal growth in 3-D composites follows a non-three-dimensional truncated spherical direction. This study provides a deeper understanding of the crystallization behavior of protein-synthetic polymer biocomposite materials and offers experimental and theoretical guideline for the regulation and utilization of their structure and properties for the design of new biocomposite materials.

Automated summary

This study investigates the melting behavior of silk fibroin/polylactic acid (SF/PLA) composite foam materials and discusses their isothermal crystallization kinetics. The results indicate the presence of α and α'-type crystals in the composite material, with their contents being adjustable by isothermal crystallization temperature. The shortest crystallization time and fastest crystallization rate were observed at an isothermal crystallization temperature of approximately 105 degrees C. Silk fibroin was found to shorten the crystallization half-life of the composite foam and enhance its crystallinity. However, higher isothermal temperatures hindered the diffusion, folding, and crystallization of the PLA segments through interaction with the SF segments. This study provides valuable insights into the crystallization behavior of protein-synthetic polymer biocomposite materials and offers guidance for the design of new biocomposite materials.