Robust and Flexible Films from 100% Starch Cross-Linked by Biobased Disaccharide Derivative

In this research, oxidized sucrose, a novel aldehyde-based green cross-linker, endowed starch films with substantial improvement in both tensile strength and elongation, whereas many other cross-linkers did not. Starch films are usually weak, brittle, and highly moisture sensitive, and thus have restricted industrial applications. Cross-linking is one of the most common methods to tackle these problems. However, most of the available cross-linkers are either toxic, expensive, or with low cross-linking efficiencies. Oxidized sucrose is a green cross-linker with multiple aldehyde groups per molecule to cross-link starch molecules via forming hemiacetals/acetals. The starch films cross-linked with oxidized sucrose had tensile strength and breaking elongation of 23 MPa and 60%, respectively, exceeding the cross-linking results of many other cross-linkers. Oxidized sucrose cross-linking also substantially increased the stability of starch films in both water and formic acid. With activation energy as low as 33.22 kJ mol^-1, the cross-linking, a pseudo-first-order reaction, could occur readily. Mild cross-linking using oxidized sucrose might provide an alternative to promote industrialization of starch-based products.