Dehydrogenation Polymer (DHP) Condensation Reaction with Glucose

Abstract

Dehydrogenation polymer (DHP) was synthesized by free radical coupling dehydrogenation polymerization of the lignin precursor coniferin under the catalysis of various enzymes. DHP has a highly similar connection structure to natural lignin (such as β-O-4, β-β, β-5, etc.), so it shows the potential as a new zero formaldehyde release adhesive. In plants, a very stable lignin-carbohydrate complex (LCC) is formed between lignin and cellulose and hemicellulose, which makes plants have excellent mechanical strength. In this paper, the thermal condensation reaction between DHP and D-glucose-¹³C₆ was simulated by hot pressing of wood-based panels, and the DHP-D-glucose-¹³C₆ complex was prepared. The condensation was analyzed by Fourier Transform Infrared (FTIR) and nuclear magnetic response (NMR) characterization. The signals of C₁ and C₆ of glucose in the complex could be clearly observed in the FTIR and NMR spectra, which showed that DHP and D-glucose-¹³C₆ can undergo thermal condensation reaction in the simulated hot-pressing environment. The C₁ on the glucose unit may form a C-C bond with the C₆ on the aromatic ring in DHP. It was found that DHP can function as a formaldehyde-free wood-based panel adhesive, thereby providing new evidence about the mechanism of adhesion within plant fibers.