Hydrophobic and Melt Processable Starch‐Laurate Esters: Synthesis, Structure–Property Correlations

ABSTRACT A controlled esterification of starch to replace the OH moieties with bio‐derived medium chain fatty acids, and the changes in the polymer structure and properties for material applications is investigated in this research. The esterification is conducted via a homogeneous esterification process using an activated lauric acid (C 12 ) in the presence of a base catalyst. The degree of esterification through the replacement of hydroxyl groups of starch was estimated using elemental analysis (EA) and proton NMR. The effect of the modification on the structural and material properties of the modified starch polymer is elucidated by evaluating the changes in morphology, network thermal stability, hydrophobicity, solubility profile, and thermal transition events. Scanning electron microscopy imaging reveals structural changes ranging from surface roughness to complete disruption depending on the degree of substitution. This is confirmed by XRD. Because of the esterification of starch, the resulting polymers become melt processable thermoplastic that forms a transparent film with an elastic storage modulus of up to 226 MPa at room temperature. This shows that the starch–fatty acid polymer can be used for various industrial and advanced material applications without any other plasticizers or modifiers. The final material is completely bio‐based, and is expected to be biodegradable in the environment. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56 , 2611–2622