Structure of β-chitin from Berryteuthis magister and its transformation during whisker preparation and polymerization filling

• Structure of native, deproteinized and swollen β-chitin was explored by X-ray methods.
• Polymerization of acrylic acid takes place in the interfibrillar space of chitin.
• Nanofibrils of 4–6 nm in diameter and several microns in length were obtained.

Models for the structures of the β-chitin–protein complex of native and deproteinized squid pen (Berryteuthis magister) based on SAXS and WAXS data are proposed. Chitin fibrils of 25 Å in diameter and persistence length of 1200 Å are immersed in protein matrix. Average distance between fibrils is 42 Å. Deproteinization of the squid pen led to disappearance of the lateral fibril order stabilized by the protein matrix of the native sample. Swelling in water and acrylic acid resulted in an increase in the chitin 010 d-spacing to 14 and 18 Å, respectively. A preparation routine for individual chitin nanofibers of few microns in length and with diameter of 40–60 Å has been developed. During exfoliation of the chitin in acrylic acid the degree of acetylation does not change. Chitin-based nanocomposites can be prepared by polymerization of acrylic acid in swelled deproteinized samples which takes place mainly in the interfibrillar space of β-chitin mainly.