title: Pure, transparent-melting starch esters: synthesis and characterization.
abstract: Long chain starch esters were prepared by a new method using molten imidazole as solvent for the biopolymer. The advantage is the simplicity of the reaction mixture. Imidazole is acting not only as solvent, but also as reagent and base. The reaction succeeds via the imidazolide, which is formed in situ with an acid chloride. It yields highly pure derivatives, as could be shown by NMR spectroscopy and elemental analysis. No hints for desoxychloro substituents or other impurities could be found. The high quality of the products prepared is responsible for the occurrence of colorless melts. Although DSC measurements show a variety of thermal transitions, the formation of melts in the range of 40 to 255 °C could be observed with a hot stage microscope. The melting behavior can be adjusted by the type of ester moiety and the amount of ester functions introduced. In case of starch palmitates completely transparent melts are obtained within two distinct DS regions namely around 1.5 and 2.2 to 3.0. Upon cooling the melts form homogeneous films on different supports including glass. They show good adhesion and should therefore be a suitable basic material for the preparation of composites like laminated glass.
authors.affiliation: Institute of Organic Chemistry and Macromolecular Chemistry, Center of Excellence for Polysaccharide Research, Friedrich Schiller University of Jena, Humboldtstraße 10, D-07743 Jena, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Liebert
authors.forename: Matilde C V
authors.initials: MC
authors.lastname: Nagel
authors.forename: Torsten
authors.initials: T
authors.lastname: Jordan
authors.forename: Andreas
authors.initials: A
authors.lastname: Heft
authors.forename: Bernd
authors.initials: B
authors.lastname: Grünler
authors.forename: Thomas
authors.initials: T
authors.lastname: Heinze
mesh_terms: D002208:Caproates / Q000737:chemistry; D060326:Chemistry Techniques, Synthetic; D004952:Esters; D007093:Imidazoles / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010168:Palmitates / Q000138:chemical synthesis*; D012997:Solvents; D013213:Starch / Q000737:chemistry*; D013696:Temperature
chemical_list: D002208:Caproates; D004952:Esters; D007093:Imidazoles; D010168:Palmitates; D012997:Solvents; C029899:imidazole; D013213:Starch