COLL 383 |
| Robert Y. Lochhead and Joan B. Schuman. School of Polymers and High Performance Materials, University of Southern Mississippi, Hattiesburg, MS 39406 |
| The objective of this study was to investigate the role of polysaccharide backbone flexibility on adsorption at the oil/water interface and on emulsification by studying hydrophobically modified dextran - a polysaccharide having a flexible a-D linkage. Dextran was hydrophobically modified from 1to 2.4 mole% by reacting with stearyl isocyanate. Above the critical overlap concentration, dextran hydrophobically modified with C8or C12 alkyl chains consistently displayed viscoelastic solutions in which the viscous modulus dominated but dextran with a C18 hydrophobe produced elastic gels. The area per adsorbed macromolecule was greatest for the lowest molecular weight and the lowest of alkyl chain lengths. This indicates that these highest molecular weight, highest alkyl chain length substituted dextrans adsorb as globular aggregates or unimolecular micelles and the lower molecular weight, lower alkyl chain-substituted dextrans adsorb in a flatter conformation. The octadecyl-substituted dextrans adsorbed as a strongly elastic film at the interface. |
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Symposium in Memory of Arthur W. Adamson
8:30 AM-12:10 PM, Wednesday, March 31, 2004 Marriott -- Orange County 4, Oral
Division of Colloid and Surface Chemistry |