Alexandre Velhinho

tInspired by chitin based hierarchical structures observed in arthropods exoskeleton, this work reportsthe capturing of chitin nanowhiskers’ chiral nematic order into a chitosan matrix. For this purpose, highlycrystalline chitin nanowhiskers (CTNW) with spindle-like morphology and average aspect ratio of 24.9were produced by acid hydrolysis of chitin. CTNW were uniformly dispersed at different concentrationsin aqueous suspensions. The suspensions liquid crystalline phase domain was determined by rheologicalmeasurements and polarized optical microscopy (POM). Chitosan (CS) was added to the CTNW isotropic,biphasic and anisotropic suspensions and the solvent was evaporated to allow films formation. The Films’morphologies as well as the mechanical properties were explored. A correlation between experimentalresults and a theoretical model, for layered matrix’ structures with fibers acting as a reinforcement agent,was established. The results evidence the existence of two different layered structures, one formed bychitosan layers induced by the presence of chitin and another formed by chitin nanowhiskers layers.By playing on the ratio chitin/chitosan one layered structure or the other can be obtained allowing thetunning of materials’ mechanical properties.