Structure and properties of silk fibroin aerogels prepared by non-alkali degumming process

Silk fibroin aerogel generally suffers from weak mechanical properties, which limits its application in the highperformance materials. Hence, we develop a non-alkali urea degumming strategy for the raw silk to improve the mechanical properties of silk fibroin aerogel. The silk fibroin aerogel with a low density of 13.43 +/- 0.77 mg/cm(3) was fabricated successfully via silk fibroin dissolution, dilution and freeze-drying. We systematically analyze the solution properties of silk fibroin prepared via alkali degumming and non-alkali degumming. Meanwhile, the morphology and structure of aerogel are characterized by scanning electron microscopy, X-ray diffraction spectroscopy and Gaussian multi-peaks-fiting technique of infrared spectrum. Moreover, we investigate the effects of non-alkali degumming method on the mechanical properties and thermal stability of aerogels. The results manifest that the non-alkali urea degumming process reduces damage to silk fibroin, leading to the stable three-dimensional skeleton structure of the prepared aerogels. Furthermore, compared with the silk fibroin aerogel prepared by alkali degumming, the silk fibroin aerogel prepared by non-alkali degumming has higher crystallinity and content of beta-sheet structure, resulting in the better mechanical properties and thermal stability. This work may pave the way for the fabrication of silk fibroin aerogel materials with high mechanical properties.