Five chitosan with different acetylation degree (DA), molar masses and origin were depolymerized by nitrous acid treatment in acidic media leading to water soluble 2,5 anhydro-Dmannose end chain oligomers with DPn<20. The kinetics of the reaction was studied and the best work conditions were found to be 3h reaction at 50°C. It was shown that the DPn of oligomers only depends on the quantity of NaNO2 involved. Molar masses or DA do not have an impact on the depolymerization process when targeting oligomers with less than 20 units. This depolymerization process also leads to free AMF that might react with the free amines of obtained oligomers to form imines. This reaction is pH dependant and in acidic condition, leads to the formation of 5-hydromethyl-2-furfural (HMF). At the end, the oligomers were purified with dialysis to get rid of most free AMF (<5%) and other residual salts, and appeared to have no acute toxicity.

Four different films were prepared from chitosan modified with furfuryl glycidyl ether (FG) by Diels Alder reaction with different maleimide-based cross linker. At first, a preliminary study led to structural identification and better understanding of the reaction. For the first time, Diels-Alder and retro Diels-Alder reactions were evidenced by NMR spectroscopy and DSC on chitosan based systems. Then, chitosan of 30,000 g/mol and 150,000 g/mol were modified by FG with 20% substitution degree (DS). The resulting products were then crosslinked with bis and trimaleimide cross-linkers to produce films possessing interesting mechanical properties. For the first time for chitosan-based films, DMA measurement highlighted retro Diels-Alder between 110 and 130°C. Film also showed interesting hydrophobicity and fat absorption. They also exhibited resistance in acidic media whereas crude chitosan films were destroyed.

Hydrophobically modified chitooligosaccharides (COS) were tested for suitability as an emulsifier in cationic bituminous emulsions. COS of polymerization degree (DP) 5, 10, 15 and 20 were obtained by nitrous acid deamination. A complete study on depolymerization and precise product and side product characterization was led upstream. Chemical modification of COS was performed to reach amphiphilic structures using three fatty epoxide with growing chain length (Butyl (C4), octadecyl (C9) and hexadecyl glycidyl ether (C16)). The grafting efficiency according to reaction conditions were established.Different substitution degrees (DS) were obtained by modulating the ratio of fatty epoxy/NH 2 . It was shown that after a certain DS, the oligomers thus formed were not watersoluble anymore. At the end, cardanol glycidyl ether was grafted on DP 5, 10 and 15 COS, cardanol being a biobased compound extracted from cashew nut shell, this reaction led to a potentially fully biobased structure. Water-soluble candidates with higher DS were used as surfactant to emulsify motor oil as a simulation of bitumen. Cardanol-chitosan based surfactant led to direct oil in water emulsion (60/40 w/w) formed of particles of 15 µm average that were stable at least for 24 h.