LignoSwitch: A Robust Yet Reversible Bioaromatic Superglue for Enhanced Materials Circularity and Ecodesign

Design for circularity and the efficient use of renewable resources are of key importance to reach the full potential of a circular economy. Adhesives and glues have important roles to play to support circular and sustainable products, but they are currently still largely derived from fossil resources and the use of nondebondable adhesives burdens the recycling of valuable materials. Herein we report a superglue, called LignoSwitch, displaying a very rare combination of usually mutually exclusive sustainable attributes: It is >90% biobased, nontoxic, easy to apply, and can rapidly and repeatedly switch on-demand between a strongly adhesive solid state and a nonadhesive liquid state. The superglue integrates lignin and fatty acids, connected via thermoreversible Diels-Alder bonds that dissociate and associate upon heating and cooling, respectively. The use of LignoSwitch as an ecodesign tool facilitating materials recovery is demonstrated with conceptual examples, highlighting the added value of such materials for a circular materials bioeconomy.