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

Lignin composed solely of caffeyl alcohol units, or C-lignin, was recently discovered in the seed coats of a number of vanilla orchid and cactus species. The caffeyl alcohol monomer polymerizes into a highly uniform benzodioxane backbone, making C-lignin a promising substrate for lignin valorization, where heterogeneity is a key challenge. In this study, we used reductive catalytic fractionation (RCF) on vanilla seeds to investigate the depolymerization of naturally grown C-lignin. To overcome challenges associated with the high extractive content and poor sugar retention in vanilla seeds, the ratio of monomer yield to total lignin yield was used to isolate the depolymerization efficiency of C-lignin from the extraction efficiency of lignin from seeds. This approach allowed us to compare extents of depolymerization across lignin types and biomass feedstocks. C-Lignin RCF generated extents of depolymerization akin to those of hardwoods, despite observing incomplete benzodioxane cleavage due to catalyst deactivation caused by the seed extractives. In addition, depolymerization of C-lignin produced a favorable monomeric product distribution consisting of only propyl and propenyl catechol. These promising results suggest that genetic modification of other plant species to incorporate C-lignin has the potential to yield a single, valuable catechol product via RCF.

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.

The success of long-lasting low-cost (nonplatinum) alkaline fuel cells is dependent on the development of anion exchange membranes (electrolyte separator) with high alkaline chemical stability. In this study, a series of methacrylate-based polymerized ionic liquids (PILs) were synthesized with various covalently attached cations: butylimidazolium, butylmethylimidazolium, trimethylammonium, pentamethylguanidinium, butylpyrrolidinium, and trimethylphosphonium. The alkaline chemical stability of these PILs was examined in tandem with their analogous ionic salts: 1-butyl-3-methylimidizolium chloride, 1-butyl-2,3-dimethylimidazolium chloride, tetramethylammonium chloride, benzyltrimethylammonium chloride, hexamethylguanidinium chloride, 1,1-butylmethylpyrrolidinium chloride, and tetramethylphosphonium chloride. The degradation mechanisms and extent of degradation were quantified using 1 H NMR spectroscopy at various pHs (in D 2 O), and temperature. The PILs with imidazolium and pyrrolidinium cations showed enhanced chemical stability relative to the PILs with ammonium and phosphonium cations. Interestingly, direct correlations were not observed between the PILs and their analogous small molecule ionic salts; significant degradation was observed in imidazolium ionic salts, most notably at high temperature/high pH conditions, while the pyrrolidinium-, ammonium-, and phosphonium-based ionic salts showed no degradation under any of the conditions examined. Additionally, results on the imidazolium ionic salts showed that methyl substitution in the C2 position limited the ring-opening degradation reaction, whereas the PIL with the unsubstituted imidazolium actually showed higher chemical stability relative to its substituted PIL counterpart. Overall, the alkaline chemical stability of the PILs in this study showed no correlation to that of their analogous small molecule ionic salts, suggesting that alkaline chemical stability studies on small molecules may not provide a solid basis for evaluating alkaline stability in polymers, counter to the hypothesis in many previous studies. ■ INTRODUCTIONAlkaline fuel cells (AFCs) employing solid-state anion exchange membranes (AEMs) as electrolytes are of great interest, as they produce high power densities at low operating temperatures (<200°C) and enable the use of non-platinum electrodes (e.g., nickel), significantly reducing cost relative to proton exchange membrane fuel cells. 1 Recently, a number of AEMs have been developed for the AFC. 2−30 One of the critical challenges limiting the wide scale use of solid-state AFCs is the alkaline chemical stability of the AEM. Degradation of the covalently tethered cationic groups, as well as the polymer backbone, may be triggered by the high nucleophilicity and basicity of OH − ions, which are produced in an AFC and transported through the AEM. Although degradation of the polymer backbone should be considered, it is generally accepted as more chemically stable than the cation. Further investigations are necessary to determine the most prom...

Polymerized ionic liquid (PIL) block copolymers are an emerging class of polymers that synergistically combine the benefits of both ionic liquids (ILs) and block copolymers into one, where the former possesses a unique set of physiochemical properties and the latter self assembles into a range of nanostructures. The potential to synthesize a vast array of new block copolymers is almost limitless with numerous IL cations and anions available. In this paper, we highlight the very recent work on PIL block copolymers, specifically, synthesis and unique solid-state properties for electrochemical energy.