cited By 1International audienceChitin is the second natural polymer available at the earth surface. The chemical structure is composed of N-acetylglucosamine units and the physical structure shows three different forms due to the arrangement of the macromolecular chains. The major problem encountered in the chitin chemistry is its preparation and its extraction to obtain a chitin with characteristics similar to the original polymer (molar mass and acetylation degree). The different treatments used for its extraction are discussed. Chitin is poorly valorised due to difficulties to be processed related to a bad solubilisation. Many derivatives are prepared, particularly chitosan obtained from the deacetylation of chitin. This derivative has the particularity to have amino groups and hence to be a cationic polyelectrolyte, in acidic medium, due to protonation of these groups. The degree of acetylation, the molar mass but also the repartition of N-acetylated units along the macromolecular chain are characteristics of the macromolecular chain. These characteristics allow this polymer to have original properties compared with other polysaccharides which are generally anionic. These properties and applications are discussed, demonstrating the large range of domains in which this polymer may be used
