Click Synthesis of Triazole Polymers Based on Lignin-Derived Metabolic Intermediate and Their Strong Adhesive Properties to Cu Plate

2-Pyrone-4,6-dicarboxylic acid (PDC) is a chemically stable metabolic intermediate of lignin that can be produced on a large scale by transforming bacteria. Novel biomass-based polymers based on PDC were synthesized by Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and fully characterized by nuclear magnetic resonance, infrared spectroscopies, thermal analysis, and tensile lap shear strength measurements. The onset decomposition temperatures of these PDC-based polymers were all above 200 °C. In addition, the PDC-based polymers exhibited strong adhesive properties to various metal plates, with the highest adhesion to a copper plate of 5.73 MPa. Interestingly, this result was in contrast to our previous findings that PDC-based polymers weakly adhere to copper. Furthermore, when bifunctional alkyne and azide monomers were polymerized in situ under hot-press conditions for 1 h, the resulting PDC-based polymer displayed a similar adhesion to a copper plate of 4.18 MPa. The high affinity of the triazole ring to copper ions improved the adhesive ability and selectivity of the PDC-based polymers to copper while still maintaining the strong adhesive ability to other metals, which is conducive to enhancing the versatility of PDC-based polymers as adhesives.

Utilization of Lignocellulosic Biomass via Novel Sustainable Process

In this review, we show novel methods for utilizing lignocellulosic biomass, polysaccharides, and lignin. Firstly, the simultaneous enzymatic saccharification and comminution (SESC) of plant materials is described as an extraction method for lignocellulosic biomass that does not require toxic reagents or organic solvents. Secondly, we demonstrate the material utilization of non-deteriorated lignocellulosic biomass extracted by SESC, such as for sugar and ethanol synthesis, and as a heatproof filler. Finally, we exhibit the use of a functional monomer (e.g., in disinfection chemicals, cesium chelation, and building blocks for polymers), 2-pyrone-4,6-dicarboxylic acid, derived from lignin via metabolic degradation.