title: Synthesis and properties of fatty acid starch esters.
abstract: Being completely bio-based, fatty acid starch esters (FASEs) are attractive materials that represent an alternative to crude oil-based plastics. In this study, two synthesis methods were compared in terms of their efficiency, toxicity and, especially, product solubility with starch laurate (C12) as model compound. Laurates (DS>2) were obtained through transesterification of fatty acid vinylesters in DMSO or reaction with fatty acid chlorides in pyridine. The latter lead to higher DS-values in a shorter reaction time. But due to the much better solubility of the products compared to lauroyl chloride esterified ones, vinylester-transesterification was preferred to optimize reaction parameters, where reaction time could be shortened to 2h. FASEs C6-C18 were also successfully prepared via transesterification. To determine the DS of the resulting starch laurates, the efficient ATR-IR method was compared with common methods (elementary analysis, (1)H NMR). Molar masses (Mw) of the highly soluble starch laurates were analyzed using SEC-MALLS (THF). High recovery rates (>80%) attest to the outstanding solubility of products obtained through transesterification, caused by a slight disintegration during synthesis. Particle size distributions (DLS) demonstrated stable dissolutions in CHCl3 of vinyl laurate esterified - contrary to lauroyl chloride esterified starch. For all highly soluble FASEs (C6-C18), formation of concentrated solutions (10 wt%) is feasible.
authors.affiliation: Fraunhofer Institute for Applied Polymer Research, Division Biopolymers, Department Starch/Molecular Structure, Geiselbergstr. 69, 14476 Potsdam, Germany. henning.winkler@iap.fraunhofer.de
authors.forename: Henning
authors.initials: H
authors.lastname: Winkler
authors.forename: Waltraud
authors.initials: W
authors.lastname: Vorwerg
authors.forename: Hendrik
authors.initials: H
authors.lastname: Wetzel
mesh_terms: D060326:Chemistry Techniques, Synthetic; D004951:Esterification; D004952:Esters; D005227:Fatty Acids / Q000737:chemistry*; D055772:Green Chemistry Technology; D007850:Lauric Acids / Q000737:chemistry; D008970:Molecular Weight; D012995:Solubility; D013213:Starch / Q000138:chemical synthesis* / Q000737:chemistry*
chemical_list: D004952:Esters; D005227:Fatty Acids; D007850:Lauric Acids; C030358:lauric acid; D013213:Starch
keywords: DLS; DS-determination; Esterification; Fatty acid starch ester; SEC-MALLS; Solubility