Interaction-density-directed supramolecular engineering in lignin toward adhesive–porous composite materials

Achieving structurally integrated adhesive and porous materials from heterogeneous biopolymers remains challenging because current strategies typically rely on covalent modification, multicomponent blending, or separately processed constituents. Here, we report an interaction-density-directed supramolecular engineering strategy to derive adhesive and porous architectures from a single lignin platform. Driven by enhanced hydrogen-bonding and electrostatic interactions, an interfacial amphiphilic agent (IAA)-mediated lignin network exhibits restricted chain mobility, enabling rapid interfacial locking at room temperature. In this regime, the lignin system functions as a strong supramolecular adhesive with lap shear strengths of up to 5.46 MPa. By combining pre-oxidation with reduced effective interaction density and thermal activation, the same platform is redirected into a porous architecture featuring low density, high specific surface area, low thermal conductivity, and enhanced flame retardancy. Because both the adhesive and porous components are derived from the same lignin-based supramolecular platform, they can be assembled with wood veneers into a sandwich composite comprising veneer facings, adhesive interlayers, and a multifunctional porous foam core for bonding, thermal insulation, flame retardancy, and formaldehyde capture.