Flexible and wet stable starch films crosslinked with sugar-based aldehydes

Abstract Starch films always suffer from brittleness and poor wet stability. Besides, numerous reinforcements have enormous limitations. Because of the high reactivity, sugar aldehydes should have substantially improved properties of starch products. However, sugar-aldehydes not only had limited property improvement of starch products but also contained a significant amount of formaldehyde. Various saccharides were oxidized under different conditions to evaluate the generation of formaldehyde and crosslinking performance. Mechanical properties of starch films were controlled by length and concentrations of crosslinkages from formyl-saccharides. Via engineering crosslinkages of formyl-saccharides, tensile strength and breaking elongation of starch films were improved from 7 MPa and 5%–25 MPa and 28 %, respectively. Formyl-saccharide crosslinkages also ensured 93 % weight retention of starch film in water and unchanged cytocompatibility. Less than 2% of crosslinkages formed by formyl-saccharides were damaged at 50 °C for 7 days at various pHs. This work demonstrates that starch films with desirable tensile strength, flexibility, wet stability and cytocompatibility can be developed via structure-controlled formaldehyde-free formyl-saccharide crosslinkages.