Catalytic Transesterification of Starch with Plant Oils: A Sustainable and Efficient Route to Fatty Acid Starch Esters.

The transesterification of maize starch with olive oil or high oleic sunflower oil was studied under homogeneous conditions in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as catalyst. Most importantly, this method used two renewable resources directly, without any pretreatment or derivatization, for the synthesis of polymeric materials with desirable properties. Moreover, the solvent, oils, and catalyst could be recovered through facile work-up and reused for further modifications. The obtained fatty acid starch esters (FASEs) were highly soluble in common organic solvents and were thoroughly characterized. Degrees of substitution (DS) were calculated using (31) P NMR spectroscopy, and DS values of approximately 1.3 were obtained. Differential scanning calorimetry analysis revealed thermal transitions of the modified starches at approximately 80-90 °C. Films were produced from these FASEs, and their hydrophobic surfaces were characterized using contact-angle measurements. Furthermore, mechanical properties were examined using tensile strength measurements and showed approximately 40 and 80 % elongation at break for modified maize starch and modified amylose from maize, respectively.