High strength nanostructured films based on well-preserved β-chitin nanofibrils

Chitin nanofibrils (ChNF) are interesting high-value constituents for nanomaterials due to the enormous amount of waste from the seafood industry. So far, the reported ChNFs are substantially modified and chemically degraded (shortened) during extraction from the organisms. Here, highly individualized and long native-state β-chitin nanofibrils from Illex argentinus squid pens are prepared. A mild treatment was developed to preserve the molar mass, aspect ratio, degree of acetylation and crystallite structure. The fibrils show a uniform diameter of 2-7 nm, very high aspect ratio (up to 750), high degree of acetylation (DA = 99%), and high molar mass (843 500 dalton). The powder X-ray diffraction analysis showed the preserved crystallite structure after protein removal. These "high quality" ChNFs were used to prepare nanostructured films via vacuum filtration from stable hydrocolloids. The effects of well-preserved "native" fibrils on morphology, and film properties (mechanical and optical), were studied and compared with earlier results based on coarser and shorter, chemically degraded chitin fibrils.