Ductile keratin/deacetylated chitin composites with nanoparticle-induced formation of ordered and entangled structures

Highly ductile and wet-durable bio-composites from keratin reinforced by chitin-nanoparticles with engineered deacetylation have been developed. Though featuring good biodegradability and biocompatibility, poultry-feather-extracted keratin-based composites usually suffered from poor ductility and moisture stabilities because of poor interfacial properties, limited recovery of ordered protein structures and crosslinkages. In this work, chitin-nanoparticles with engineered deacetylation were used to reinforce keratin. Via engineered deacetylation, chitin-nanoparticles not only improved interfacial interactions but also formed crosslinkages with keratin. As a result, ordered keratin structures with high degree of entanglement in composites were substantially formed without addition of any coupling agents. Furthermore, engineered deacetylation for chitin could adjust the wet performance of composites via control of hydrophilicity of matrix and reinforcements. Via control of regularity and hydrophilicity of molecules by chitin-nanoparticles, mechanical properties and wet performance of keratin-based composites can be substantially improved. Reinforced keratin composites had a 230%, 260%, 540% increase in breaking strain, breaking stress and ductility, respectively as well as 94% weight retention after immersed in water for 1 week.