Hydrophobic alkyl chains-pectin conjugates. Comparative study of some physicochemical properties in relation to covalent coupling vs ionic association

Various amphiphilic conjugates in which pectin ia polyanionic polysaccharide) is associated with hydrophobic dodecyl chains were prepared. The syntheses were carried out according to two different pathways, one affording covalent immobilization via ester bond formation, the other where a long chain alkylamine (dodecylamine) is reacted with the polysaccharide carboxyl groups, to yield the corresponding dodecylammonium salts. The present article focus on the comparative study of some physicochemical properties of these C-12 derivatives. Surface tension measurements on dilute solutions evidenced opposite behaviors of the two types of conjugates. Rheological properties in the semidilute regime were also investigated, and the similarities and differences observed are tentatively interpreted in connection with the mode of association, covalent vs ionic, of the hydrophobic dodecyl chains on the polysaccharide.