Efficient catechol functionalization of high oleic sunflower oil for the preparation of fully biobased and extrudable acetal CANs

Abstract

Herein, we introduce the synthesis of fully renewable and extrudable high oleic sunflower oil-based acetal containing covalent adaptable networks (CANs) via a catalyst and solvent-free click-like reaction between a bio-based polyol and divinyl ether, i.e. 1,4-cyclohexanedimethanol divinyl ether. High oleic sunflower oil was therefore first converted into the respective polyol via a simple H₂SO₄ catalyzed Friedel–Crafts alkylation using catechol within 30 minutes at 120 °C. After subsequent structural characterization of the polyol, acetal containing CANs showing high cross-linking densities, fast stress relaxation, and excellent malleability were synthesized without releasing any small-molecule byproducts. The presence of the catechol moiety is particularly interesting, as the presence of an adjacent phenolic group induces neighboring group participation effects and accelerates exchange reaction rates. The dynamic behavior of the new cross-linked materials was confirmed by stress relaxation measurements at different temperatures as well as by their reprocessability via compression molding and extrusion. Additionally, the materials were degraded under weak acidic conditions, and the starting biobased polyol was recovered in a yield of 72%, thus enabling a closed-loop chemical recycling of this monomer.