Synthetic semicrystalline cellulose oligomers as efficient Pickering emulsion stabilizers.

Nanocellulose are promising Pickering emulsion stabilizers for being sustainable and non-toxic. In this work, semicrystalline cellulose oligomers (SCCO), which were synthesized from maltodextrin using cellobiose as primer by in vitro enzymatic biosystem, were exploited as stabilizers for oil-in-water Pickering emulsions. At first, the morphology, structure, thermal and rheological properties of SCCO suspensions were characterized, showing that SCCO had a sheet morphology and typical cellulose-Ⅱ structure with 56 % crystallinity. Then the kinetic stabilities of emulsions containing various amounts of SCCO were evaluated against external stress such as pH, ionic strength, and temperature. Noting that SCCO-Pickering emulsions exhibited excellent stabilities against changes in centrifugation, pH, ionic strengths, and temperatures, and it was also kinetically stable for up to 6 months. Both SCCO suspensions and their emulsions exhibited gel-like structures and shear-thinning behaviors. These results demonstrated great potential of SCCO to be applied as nanocellulosic emulsifiers in food, cosmetic and pharmaceutical industries.

Cellulose oligomers production and separation for the synthesis of new fully bio-based amphiphilic compounds.

Cellulose oligomers are water-soluble, on the contrary to cellulose, which greatly increase their application range. In this study, cellulose oligomers were obtained from the acidic hydrolysis of cellulose with phosphoric acid. The global yield in water-soluble oligomers was around 23% with polymerization degree (DP) ranging from 1 to 12. The cellulose oligomers DP distribution was successfully reduced by differential solubilisation in methanol as one of the goals of this work was to avoid the use of a time-consuming full chromatographic separation. The methanol-soluble oligomers were mainly low DP (≤3). The oligomers of higher molar mass, composed of 42% of cellotetraose and 36% of cellopentaose, were then functionalized and coupled with stearic acid through azide-alkyne click chemistry to obtain amphiphilic compounds. The self-assembly of these new bio-based compounds was finally investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM) and their critical micellar concentration (CMC) was found to be in the same range as alkylmaltosides and alkylglucosides.