Submitted to: Polymer Preprints
Publication Type: Proceedings
Publication Acceptance Date: 7/25/2008
Publication Date: 8/21/2008
Citation: Biswas, A., Shogren, R.L., Willett, J.L. 2008. Ionic liquid 1-butyl-3-methylimidazolium cyanamide (bmim [dca]) as a solvent and catalyst for acylation of maltodextrin. Polymer Preprints. xx.
Interpretive Summary: Among the industrial materials, starch is one of the cheapest and most cost-effective. In addition to being a major food item, it is currently used industrially as coatings and sizing in paper, textiles and carpets, as binders and adhesives, as absorbants, and as encapsulants. Hydrolysis of starch produces a group of low-molecular-weight carbohydrates named dextrins. Dextrins are mixtures of linear a-(1,4)-linked D-glucose polymers. They have the same general formula as carbohydrates but are of shorter chain length. Dextrins find widespread use in industry, due to their non-toxicity and their low price. They are used as water soluble glues, as thickening agents in food processing, and as binding agent in pharmaceuticals. In pyrotechnics they are added to colored fire formulas, allowing them to solidify as pellets or "stars." Cyclodextrins find additional use in analytical chemistry as a matrix for the separation of hydrophobic substances, and as excipients in pharmaceutical formulations. Not all forms of dextrin are digestible, and indigestible dextrin is sometimes used in fiber supplements. For example, maltodextrin is a moderately sweet polysaccharide used as a food additive. In the U.S. this starch is usually corn or potato, elsewhere such as in Europe it is commonly wheat and is usually found as a creamy white hygroscopic powder. Maltodextrin is easily digestible, being absorbed as rapidly as glucose. In this work, we found an inert solvent for maltodextrins that also catalyzed the esterification reaction with vinyl esters. This would enable us to improve the starch or dextrin properties by modifying those with many reactants that would have been impossible otherwise. This study has shown that starch stearates of a range of DS and solubilities can be prepared simply by heating starch, ionic liquid bmim[dca] and vinyl stearate or stearic acid. We developed a method to prepare starch acetate by the use of cheap stearic acid rather than the much more expensive vinyl stearate. Our methodology may help making such novel starch esters more practical as previous methods to starch stearate have required the use of vinyl stearate as well as a harsh chemical or enzymatic catalyst. Some applications for these materials may include coatings, emulsifiers, dispersing agents and nanoparticles.
Technical Abstract: We have found a novel method to prepare maltodextrin stearate with DS upto 0.60 in 90% yields from maltodextrin in IL bmim[dca] reacted with vinyl stearate or stearic acid. In this work we have demonstrated that IL could simultaneously act as a solvent and as a catalyst for reaction of maltodextrin with vinyl ester or stearic acid. The ability to use cheap stearic acid rather than the much more expensive vinyl stearate may help to make such novel starch esters more practical.