Dilational rheology of air/water interfaces covered by nonionic amphiphilic polysaccharides. Correlation with stability of oil-in-water emulsions

摘要

Biodegradable polymeric emulsifiers were prepared by covalent attachment of aliphatic hydrocarbon groups onto dextran macromolecules (a bacterial nonionic polysaccharide), varying the number of attached hydrocarbon tails. Submicronic oil-in-water emulsions were prepared by sonication using previous polymeric stabilizers with oil volume fractions between 10 and 50% and two oils (hexadecane and nujol). An optimal range of dextran hydrophobic modification was evidenced conciliating a strong anchoring of polymer to oil/water interface and sufficient steric repulsions between droplets. These results were correlated to dilational rheology of air/water interfaces covered by amphiphilic dextrans. The storage stability of these emulsions was of several weeks.