We find the value of lignin for biomass processing industries via conversion to 3D-printable resin and its sustainable composites.

We report an approach for programming electrical conductivity of a bio-based leathery skin devised with a layer of 60 nm metallic nanoparticles. Lignin-based renewable shape-memory materials were made, for the first time, to program and restore the materials’ electrical conductivity after repeated deformation up to 100% strain amplitude, at a temperature 60–115 °C above the glass transition temperature (T g) of the rubbery matrix. We cross-linked lignin macromolecules with an acrylonitrile–butadiene rubbery melt in high quantities ranging from 40 to 60 wt % and processed the resulting thermoplastics into thin films. Chemical and physical networks within the polymeric materials significantly enhanced key characteristics such as mechanical stiffness, strain fixity, and temperature-stimulated recovery of shape. The branched structures of the guaiacylpropane-dominant softwood lignin significantly improve the rubber’s T g and produced a film with stored and recoverable elastic work density that was an order of magnitude greater than those of the neat rubber and of samples made with syringylpropane-rich hardwood lignin. The devices could exhibit switching of conductivity before and after shape recovery.

An ionomeric, leathery thermoplastic with high mechanical strength is prepared by a new thermal processing method from a soft, melt‐processable rubber. Compositions made by incorporation of equal‐mass lignin, a renewable oligomeric feedstock, in an acrylonitrile‐butadiene rubber often yield weak rubbers with large lignin domains (1–2 µm). The addition of zinc chloride (ZnCl2) in such a composition based on sinapyl alcohol‐rich lignin during a solvent‐free synthesis induces a strong interfacial crosslinking between lignin and rubber phases. This compositional modification results in finely interspersed lignin domains (<100 nm) that essentially reinforce the rubbery matrix with a 10–22 °C rise in the glassy‐to‐rubbery transition temperature. The ion‐modified polymer blends also show improved materials properties, like a 100% increase in ultimate tensile strength and an order of magnitude rise in Young's modulus. Coarse‐grained molecular dynamics (MD) simulations verify the morphology and dynamics of the ionomeric material. The computed result also confirms that the ionomers have glassy characteristics.

Back Cover: Lignin–a plant‐derived, weakly charged, phenolic oligomer–forms acrylonitrile‐butadiene‐lignin (ABL) when reactively mixed with nitrile rubber. With salt added, ionic interactions enhance interfacial crosslinking in ABL that results in nanoscale lignin domains. The nano‐lignin‐reinforced rubber exhibits higher strength and stiffness. Further details can be found in article number 1900059 by Amit K. Naskar and co‐workers.