Dual functionalization of carboxymethyl cellulose and alginate via Passerini three-component reaction to graft two hydrophobic moieties: Toward modular thin films.

Passerini reaction was advantageously exploited to hydrophobize carboxymethyl cellulose (CMC) and alginates (ALG) by employing various hydrophobic aldehydes and isocyanides. The Passerini reaction, carried out in ecofriendly conditions, allowed to design never described twofold hydrophobized polysaccharide derivatives via the covalent grafting of two hydrophobic moieties. The modified CMC and ALG products were in-depth characterized to guaranty the success of the modification and to calculate the degrees of substitution (DS). The impact of experimental parameters and especially the structure of the aliphatic reactants were thoroughly discussed. It appears that high conversions in carboxylic acid up to 70 % can be reached. Finally, the Passerini CMC and ALG products were processed as thin films exhibiting modular wettability properties varying from a moderate to a significant hydrophobicity adjustable by the structure of the grafts and the DS values. The film formation of selected CMC and ALG samples was examined by QCM-D experiments completed by AFM analysis under humid environment. It appears that the functionalization i) increases the adsorbed mass by inducing a more packed deposition and ii) closely governs the energy dissipation of the films. This overall approach paves the way toward new bio-based multifunctional films with potential utilizations in coating fields.