Thiol–Ene Click Cross-linking of Starch Oleate Films for Enhanced Properties

• Published in: Biomacromolecules Vol. 24; no. 12; pp. 5578 - 5588
• Main Authors: Boetje, Laura, Lan, Xiaohong, van Dijken, Jur, Kaastra, Gerbrich, Polhuis, Michael, Loos, Katja
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 11.12.2023
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/acs.biomac.3c00507

Biobased films were synthesized from starch oleate (DS = 2.2) cross-linked with polyethylene glycol with M n = 2000 and 1000 g · mol–1, and ethylene glycol, all of which were esterified with either lipoic acid (LA) or 3-mercaptopropionic acid (MPA). Cross-linking was achieved through a UV-initiated thiol-ene click, and confirmed by Fourier transform infrared spectroscopy and rheometry. The films exhibit higher degradation temperatures, and an increased degree of crystallinity as cross-linker length increased. The introduction of MPA-based cross-linkers resulted in hydrophilic films, while the contact angle was barely affected by the addition of LA-based cross-linkers. A reduction in maximum strength upon introducing the cross-linkers was observed, while an increase in elongation was observed for most of the LA-based cross-linkers. Our results demonstrate the potential for tuning the mechanical and thermal properties of starch-based films through the cross-linker choice, with some formulations exhibiting increased flexibility that may be well suited for packaging applications.