Reversible biobased adhesives enable closed-loop engineered composites.

Abstract

Ubiquitous synthetic resin adhesives based on petrochemical brings environmental burdens and health concerns. Many researchers have been focused on developing biomass-derived alternatives, and reported many strong-adhesion products with high cohesive density. However, the stabilized structure-dependent adhesion contributes to greater difficulty in recycling, especially hetero-layered composites. Here, a supramolecularly connected nanoconfined network strategy is proposed for ultra-strong yet switchable biobased adhesives, where cellulose nanoconfinement phases takes up 36.5-46.3 wt%. Dependent on thermally responsive disulfide bond, resulting adhesives achieve both excellent adhesion strength (6.02 MPa) that can support a 65 kg weight with 4 cm², and instant thermo-responsive detachment with a high switching ratio over 600 (debonding adhesion ≈0 MPa, response time ≤ 10 s). Under the alternating temperature, adhesive-based composites can be disassembled into different categories and fully recycled through the destruction of dynamic crosslinked network. The full life cycle impact assessment shows this strategy is able to avoid the inherent environmental (about 7.52 * 10² PAF m³ d/kg_emitted) and health (about 2.04 * 10^-4 cases/kg_emitted) burden. This work establishes a paradigm for closed-loop engineered composites by the substantive breakthrough of green intelligent adhesives, providing ways to alleviate environmental stress.