Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5190531 | Polymer | 2006 | 8 Pages |
Abstract
Selective chemical modification of both β-cyclodextrin (β-CD) and sodium alginate (alg) was performed in order to produce an alginate derivative possessing pendant β-CD cavities along the chain. The latter was then fully characterized in terms of chemical integrity and purity, complexation properties and ability to form hydrogels. Thus, a sodium alginate derivative modified with adipic dihydrazide (alg-ADH) and a β-cyclodextrin derivative possessing an aldehyde function on the primary face were synthesized, and both were selectively coupled by a reductive amination-type reaction. Comparison of the complexation properties of the grafted and natural β-CDs by isothermal titration calorimetry using sodium adamantane acetate as a model guest gave similar enthalpy values suggesting similar mechanisms of binding. However, the association constant for the grafted CD is slightly lower as a result of a less favorable change in the binding entropy. Investigation of the gelation ability in the presence of calcium ions led to the following order: alg > alg-ADH > alg-CD. The decrease of gelation efficiency for the modified alginate samples reflected the reduction of ionic interchain bonds as a result of the unavailability or non-accessibility of G units on the alginate backbone, due to the chemical modification and steric effect of the CD molecule for alg-CD.
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Physical Sciences and Engineering
Chemistry
Organic Chemistry
Authors
Cesar G. Gomez, Gérard Chambat, Alain Heyraud, Marcelo Villar, Rachel Auzély-Velty,